/src/wolfssl/wolfcrypt/src/random.c

Source
/* random.c
 *
 * Copyright (C) 2006-2026 wolfSSL Inc.
 *
 * This file is part of wolfSSL.
 *
 * wolfSSL is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * wolfSSL is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA
 */

/*

DESCRIPTION
This library contains implementation for the random number generator.

*/

/*
 * Random Number Generator Build Options:
 *
 * Core RNG:
 * WC_NO_RNG:               Disable RNG support entirely         default: off
 * HAVE_HASHDRBG:            Enable Hash-based DRBG (SP 800-90A) default: on
 * WC_RNG_BLOCKING:          Make RNG operations blocking         default: off
 * WC_VERBOSE_RNG:           Enable verbose RNG debug output      default: off
 * WC_RNG_SEED_CB:           Use custom seed callback function    default: off
 * WC_HAVE_RNG_BANKREF:      Enable RNG bank indirect RNG         default: off
 *                            support
 * WC_RNG_NO_AUTO_LOCK:      Leave out the lock that lets threads default: off
 *                            share one WC_RNG (lock on unless set)
 * WC_RNG_WANT_AUTO_LOCK:    Keep that lock even where this build default: off
 *                            would otherwise skip it
 * WC_RNG_AUTOFORK:          pthread_atfork handlers so a forked  default: on
 *                            child can keep using its WC_RNG     where found
 * WOLFSSL_RNG_USE_FULL_SEED: Use full-length seed for DRBG       default: off
 * WOLFSSL_GENSEED_FORTEST:  Use deterministic seed for testing   default: off
 *                            WARNING: not for production use
 * WOLFSSL_KEEP_RNG_SEED_FD_OPEN: Keep /dev/random fd open        default: off
 *                            between seed operations
 *
 * Custom RNG Sources:
 * CUSTOM_RAND_GENERATE:     Custom random word generator func    default: off
 * CUSTOM_RAND_GENERATE_BLOCK: Custom block random generator      default: off
 * CUSTOM_RAND_GENERATE_SEED: Custom seed generator function      default: off
 * CUSTOM_RAND_GENERATE_SEED_OS: Custom OS-level seed generator   default: off
 *
 * Entropy Sources:
 * HAVE_ENTROPY_MEMUSE:      Enable memory-use based entropy      default: off
 *                            source for DRBG seeding
 * ENTROPY_MEMUSE_FORCE_FAILURE: Force entropy failure (testing)  default: off
 * HAVE_GETRANDOM:           Use Linux getrandom() syscall        default: auto
 * WOLFSSL_GETRANDOM:        Use getrandom() for seed source      default: auto
 * FORCE_FAILURE_GETRANDOM:  Force getrandom failure (testing)    default: off
 * NO_DEV_RANDOM:            Don't use /dev/random for seeding    default: off
 * NO_DEV_URANDOM:           Don't use /dev/urandom for seeding   default: off
 * WC_RNG_SEED_DEVICE:       Device tried before the usual seed   default: off
 *                            sources. Must be a quoted string,
 *                            e.g. -DWC_RNG_SEED_DEVICE='"/dev/hwrng"'
 * HAVE_INTEL_RDRAND:        Use Intel RDRAND instruction         default: off
 * HAVE_INTEL_RDSEED:        Use Intel RDSEED instruction         default: off
 * HAVE_AMD_RDSEED:          Use AMD RDSEED instruction           default: off
 * IDIRECT_DEV_RANDOM:       iDirect custom /dev/random path      default: off
 * WIN_REUSE_CRYPT_HANDLE:   Reuse Windows CryptContext handle    default: off
 *
 * Entropy Tuning (for HAVE_ENTROPY_MEMUSE):
 * ENTROPY_NUM_UPDATE:       Number of updates per sample         default: 18
 *                            More updates = better entropy but slower
 * ENTROPY_NUM_UPDATES_BITS: Bits to represent ENTROPY_NUM_UPDATE default: 5
 *                            = upper(log2(ENTROPY_NUM_UPDATE))
 * ENTROPY_NUM_WORDS_BITS:   State size as 2^N entries            default: 14
 *                            Range: 8-30. Base on cache sizes.
 *                            Larger = more cache misses = better entropy
 *                            but more static memory usage.
 *
 * DRBG Health Tests:
 * WC_RNG_SEED_APT_CUTOFF:  Adaptive proportion test cutoff      default: auto
 * WC_RNG_SEED_APT_WINDOW:  Adaptive proportion test window size  default: auto
 * WC_RNG_SEED_RCT_CUTOFF:  Repetition count test cutoff         default: auto
 *
 * Hardware RNG:
 * STM32_RNG:                STM32 hardware RNG                   default: off
 * STM32_NUTTX_RNG:          STM32 RNG via NuttX                  default: off
 * WOLFSSL_STM32F427_RNG:    STM32F427 hardware RNG               default: off
 * WOLFSSL_STM32_RNG_NOLIB:  STM32 RNG without HAL library        default: off
 * WOLFSSL_PIC32MZ_RNG:      PIC32MZ hardware RNG                 default: off
 * FREESCALE_RNGA:           Freescale RNGA                       default: off
 * FREESCALE_K70_RNGA:       Freescale K70 RNGA                   default: off
 * FREESCALE_RNGB:           Freescale RNGB                       default: off
 * FREESCALE_KSDK_2_0_RNGA:  Freescale KSDK 2.0 RNGA              default: off
 * FREESCALE_KSDK_2_0_TRNG:  Freescale KSDK 2.0 TRNG              default: off
 * MAX3266X_RNG:             MAX3266X hardware RNG                default: off
 * QAT_ENABLE_RNG:           Intel QAT hardware RNG               default: off
 * WOLFSSL_ATECC_RNG:        ATECC508/608 hardware RNG            default: off
 * WOLFSSL_SILABS_TRNG:      Silicon Labs TRNG                    default: off
 * WOLFSSL_SCE_NO_TRNG:      Disable Renesas SCE TRNG             default: off
 * WOLFSSL_SCE_TRNG_HANDLE:  Renesas SCE TRNG handle              default: off
 * WOLFSSL_SE050_NO_TRNG:    Disable SE050 TRNG                   default: off
 * WOLFSSL_PSA_NO_RNG:       Disable PSA RNG                      default: off
 * HAVE_IOTSAFE_HWRNG:       IoT-Safe hardware RNG                default: off
 * WOLFSSL_XILINX_CRYPT_VERSAL: Xilinx Versal crypto RNG          default: off
 * WOLFSSL_VA416X0_TRNG:     Vorago VA416x0 hardware TRNG         default: off
 *                           (seeds Hash-DRBG; needs the VA416xx
 *                           SDK header va416xx.h on the include
 *                           path). See the wc_GenerateSeed()
 *                           implementation below for SDK API and
 *                           tuning details.
 */

#define WC_FIPS_LL_CRYPTO
#define _WC_BUILDING_RANDOM_C

#include <wolfssl/wolfcrypt/libwolfssl_sources.h>

/* on HPUX 11 you may need to install /dev/random see
   http://h20293.www2.hp.com/portal/swdepot/displayProductInfo.do?productNumber=KRNG11I

*/
#if defined(ESP_IDF_VERSION_MAJOR) && ESP_IDF_VERSION_MAJOR >= 5
    #include <esp_random.h>
#endif

#if defined(HAVE_FIPS) && \
    defined(HAVE_FIPS_VERSION) && (HAVE_FIPS_VERSION >= 2)

    #ifdef USE_WINDOWS_API
        #pragma code_seg(".fipsA$i")
        #pragma const_seg(".fipsB$i")
    #endif
#endif


#include <wolfssl/wolfcrypt/random.h>
#ifdef WC_RNG_LOCK_ATFORK
    #include <errno.h>   /* for the fork handlers, whatever the seed source */
#endif
#ifdef WC_HAVE_RNG_BANKREF
    #if defined(HAVE_FIPS) && !defined(WOLFSSL_EXPERIMENTAL_SETTINGS) && \
        !defined(WOLFSSL_FIPS_DEV)
        #error WC_HAVE_RNG_BANKREF is unsupported in FIPS configurations.
    #endif
    #include <wolfssl/wolfcrypt/rng_bank.h>
#endif
#include <wolfssl/wolfcrypt/cpuid.h>

#ifndef WC_NO_RNG /* if not FIPS and RNG is disabled then do not compile */

#ifndef NO_SHA256
    #include <wolfssl/wolfcrypt/sha256.h>
#endif
#ifdef WOLFSSL_DRBG_SHA512
    #include <wolfssl/wolfcrypt/sha512.h>
#endif

#ifdef WOLF_CRYPTO_CB
    #include <wolfssl/wolfcrypt/cryptocb.h>
#endif

#ifdef NO_INLINE
    #include <wolfssl/wolfcrypt/misc.h>
#else
    #define WOLFSSL_MISC_INCLUDED
    #include <wolfcrypt/src/misc.c>
#endif

#if defined(WOLFSSL_SGX)
    #include <sgx_trts.h>
#elif defined(USE_WINDOWS_API)
    #ifndef _WIN32_WINNT
        #define _WIN32_WINNT 0x0400
    #endif
    #define _WINSOCKAPI_ /* block inclusion of winsock.h header file */
    #include <windows.h>
    #include <wincrypt.h>
    #undef _WINSOCKAPI_ /* undefine it for MINGW winsock2.h header file */
#elif defined(HAVE_WNR)
    #include <wnr.h>
    wolfSSL_Mutex wnr_mutex WOLFSSL_MUTEX_INITIALIZER_CLAUSE(wnr_mutex);    /* global netRandom mutex */
    int wnr_timeout     = 0;    /* entropy timeout, milliseconds */
    #ifndef WOLFSSL_MUTEX_INITIALIZER
    /* Elects a single initializer for wnr_mutex. */
    wc_MutexOnceFlag wnr_mutex_inited = WOLFSSL_ATOMIC_INITIALIZER(0);
    #endif
    int wnr_inited = 0;    /* flag for whether wc_InitNetRandom() has been called */
    wnr_context*  wnr_ctx;      /* global netRandom context */
#elif defined(FREESCALE_KSDK_2_0_TRNG)
    #include "fsl_trng.h"
#elif defined(FREESCALE_KSDK_2_0_RNGA)
    #include "fsl_rnga.h"
#elif defined(WOLFSSL_WICED)
    #include "wiced_crypto.h"
#elif defined(WOLFSSL_NETBURNER)
    #include <predef.h>
    #include <basictypes.h>
    #include <random.h>
#elif defined(WOLFSSL_XILINX_CRYPT_VERSAL)
    #include "wolfssl/wolfcrypt/port/xilinx/xil-versal-trng.h"
#elif defined(WOLFSSL_RPIPICO)
    #include "wolfssl/wolfcrypt/port/rpi_pico/pico.h"
#elif defined(WOLFSSL_C2000_ENTROPY)
    #include "wolfssl/wolfcrypt/port/ti/ti-c2000-entropy.h"
#elif defined(NO_DEV_RANDOM)
#elif defined(CUSTOM_RAND_GENERATE)
#elif defined(CUSTOM_RAND_GENERATE_BLOCK)
#elif defined(CUSTOM_RAND_GENERATE_SEED)
#elif defined(WOLFSSL_GENSEED_FORTEST)
#elif defined(WOLFSSL_MDK_ARM)
#elif defined(WOLFSSL_IAR_ARM)
#elif defined(WOLFSSL_ROWLEY_ARM)
#elif defined(WOLFSSL_EMBOS)
#elif defined(WOLFSSL_DEOS)
#elif defined(MICRIUM)
#elif defined(WOLFSSL_NUCLEUS)
#elif defined(WOLFSSL_PB)
#elif defined(WOLFSSL_ZEPHYR)
#elif defined(WOLFSSL_TELIT_M2MB)
#elif defined(WOLFSSL_RENESAS_TSIP)
    /* for wc_tsip_GenerateRandBlock */
    #include "wolfssl/wolfcrypt/port/Renesas/renesas_tsip_internal.h"
#elif defined(WOLFSSL_SCE) && !defined(WOLFSSL_SCE_NO_TRNG)
#elif defined(WOLFSSL_IMXRT1170_CAAM)
#elif defined(CY_USING_HAL) && defined(COMPONENT_WOLFSSL)
    #include "cyhal_trng.h" /* Infineon/Cypress HAL RNG implementation */
#elif defined(WOLFSSL_MAX3266X) || defined(WOLFSSL_MAX3266X_OLD)
    #include "wolfssl/wolfcrypt/port/maxim/max3266x.h"
#else
    #include <errno.h>
    #if defined(WOLFSSL_GETRANDOM) || defined(HAVE_GETRANDOM)
        #include <sys/random.h>
    #endif
    /* include headers that may be needed to get good seed */
    #include <fcntl.h>
    #ifndef EBSNET
        #include <unistd.h>
    #endif
#endif

#if defined(WOLFSSL_SILABS_SE_ACCEL)
#include <wolfssl/wolfcrypt/port/silabs/silabs_random.h>
#endif

#if defined(WOLFSSL_IOTSAFE) && defined(HAVE_IOTSAFE_HWRNG)
#include <wolfssl/wolfcrypt/port/iotsafe/iotsafe.h>
#endif

#if defined(WOLFSSL_HAVE_PSA) && !defined(WOLFSSL_PSA_NO_RNG)
#include <wolfssl/wolfcrypt/port/psa/psa.h>
#endif

#if FIPS_VERSION3_GE(6,0,0)
    const unsigned int wolfCrypt_FIPS_drbg_ro_sanity[2] =
                                                     { 0x1a2b3c4d, 0x00000011 };
    int wolfCrypt_FIPS_DRBG_sanity(void)
    {
        return 0;
    }
#endif

#if defined(HAVE_INTEL_RDRAND) || defined(HAVE_INTEL_RDSEED) || \
    defined(HAVE_AMD_RDSEED)
    static cpuid_flags_t intel_flags = WC_CPUID_INITIALIZER;
    static void wc_InitRng_IntelRD(void)
    {
        cpuid_get_flags_ex(&intel_flags);
    }
    #if defined(HAVE_INTEL_RDSEED) || defined(HAVE_AMD_RDSEED)
    static int wc_GenerateSeed_IntelRD(OS_Seed* os, byte* output, word32 sz);
    #endif
    #ifdef HAVE_INTEL_RDRAND
    static int wc_GenerateRand_IntelRD(OS_Seed* os, byte* output, word32 sz);
    #endif

#ifdef USE_WINDOWS_API
    #define USE_INTEL_INTRINSICS
#elif !defined __GNUC__ || defined __clang__ || __GNUC__ > 4
    #define USE_INTEL_INTRINSICS
#else
    #undef USE_INTEL_INTRINSICS
#endif

#ifdef USE_INTEL_INTRINSICS
    #include <immintrin.h>
    /* Before clang 7 or GCC 9, immintrin.h did not define _rdseed64_step() */
    #ifndef HAVE_INTEL_RDSEED
    #elif defined __clang__ && __clang_major__ > 6
    #elif !defined __GNUC__
    #elif __GNUC__ > 8
    #else
        #ifndef __clang__
            #pragma GCC push_options
            #pragma GCC target("rdseed")
        #else
            #define __RDSEED__
        #endif
        #include <x86intrin.h>
        #ifndef __clang__
            #pragma GCC pop_options
        #endif
    #endif
#endif /* USE_WINDOWS_API */
#endif

/* RNG health states */
#define DRBG_NOT_INIT     WC_DRBG_NOT_INIT
#define DRBG_OK           WC_DRBG_OK
#define DRBG_FAILED       WC_DRBG_FAILED
#define DRBG_CONT_FAILED  WC_DRBG_CONT_FAILED

/* enforcement helper for WC_RNG_LOCK_REQUIRED and
 * WC_RNG_LOCK_ENTROPY_INVALIDATED: instance-consuming public APIs call this on
 * entry. */
static WC_MAYBE_UNUSED WC_INLINE int rng_lock_required_check(WC_RNG* rng)
{
    if (rng == NULL)
        return BAD_FUNC_ARG;
#ifndef WC_RNG_HAVE_LOCK
    return 0;
#else /* WC_RNG_HAVE_LOCK */
    else {
    #ifdef WOLFSSL_NO_ATOMICS
        WC_RNG_lock_t lock_state = rng->lock;
    #else
        WC_RNG_lock_arg_t lock_state = WOLFSSL_ATOMIC_LOAD(rng->lock);
    #endif
        if ((lock_state & WC_RNG_LOCK_REQUIRED) &&
            (! (lock_state & WC_RNG_LOCK_HELD)))
        {
            return OBJECT_NOT_LOCKED_E;
        }
        /* WC_RNG_LOCK_ENTROPY_INVALIDATED deliberately does not gate entry
         * here: on lock-required instances the lock API refuses new leases,
         * and on unlocked instances the saturated reseedCtr (see
         * wc_RNG_invalidate_entropy()) forces a credited reseed -- which
         * clears the flag -- before the next generate.  Refusing here would
         * brick unlocked instances, with no path to recovery. */
        return 0;
    }
#endif /* WC_RNG_HAVE_LOCK */
}

/* Read-only accessor for the RNG health status (enum wc_RngHealthState).
 * Returns the status, or BAD_FUNC_ARG for a NULL rng. */
int wc_RNG_GetStatus(const WC_RNG* rng)
{
    if (rng == NULL)
        return BAD_FUNC_ARG;
    return (int)rng->status;
}

/* Returns 1 if rng has an instantiated DRBG, else 0.  An in-service WC_RNG can
 * lack one: _InitRng() in HAVE_INTEL_RDRAND configurations bypasses DRBG
 * instantiation when the CPU has RDRAND (). */
int wc_RNG_DRBG_Present(const WC_RNG* rng)
{
    if (rng == NULL)
        return 0;
#if defined(HAVE_HASHDRBG) && !defined(NO_SHA256)
    if ((rng->drbgType == WC_DRBG_SHA256) && (rng->drbg != NULL))
        return 1;
#endif
#if defined(HAVE_HASHDRBG) && defined(WOLFSSL_DRBG_SHA512)
    if ((rng->drbgType == WC_DRBG_SHA512) && (rng->drbg512 != NULL))
        return 1;
#endif
    return 0;
}

#ifdef WC_RNG_HAVE_POOL
static WARN_UNUSED_RESULT int PoolPurge(WC_RNG* rng);
#endif

/* Start NIST DRBG code */
#ifdef HAVE_HASHDRBG

#define OUTPUT_BLOCK_LEN  (WC_SHA256_DIGEST_SIZE)
#define MAX_REQUEST_LEN   (0x10000)

#ifdef WC_RNG_SEED_CB

#ifndef HAVE_FIPS
static wc_RngSeed_Cb seedCb = wc_GenerateSeed;
#else
static wc_RngSeed_Cb seedCb = NULL;
#endif

int wc_SetSeed_Cb(wc_RngSeed_Cb cb)
{
    seedCb = cb;
    return 0;
}

#endif


/* Internal return codes */
enum {
    DRBG_SUCCESS = 0,
    DRBG_FAILURE = 1,
    DRBG_NEED_RESEED = 2,
    DRBG_CONT_FAILURE = 3,
    DRBG_NO_SEED_CB = 4
};

/* Numerous existing code points assume DRBG_SUCCESS is 0 -- for now, just
 * assert safety around that. */
wc_static_assert(DRBG_SUCCESS == 0);

#ifdef WOLFSSL_DEBUG_TRACE_ERROR_CODES
    enum {
        CONST_NUM_ERR_DRBG_FAILURE = DRBG_FAILURE,
        CONST_NUM_ERR_DRBG_NEED_RESEED = DRBG_NEED_RESEED,
        CONST_NUM_ERR_DRBG_CONT_FAILURE = DRBG_CONT_FAILURE,
        CONST_NUM_ERR_DRBG_NO_SEED_CB = DRBG_NO_SEED_CB
    };
    /* DRBG_SUCCESS needs to be macroized to avoid "enumerated and
     * non-enumerated type in conditional expression" in C++. */
    #define DRBG_SUCCESS (byte)DRBG_SUCCESS
    #define DRBG_FAILURE (byte)WC_ERR_TRACE(DRBG_FAILURE)
    #define DRBG_NEED_RESEED (byte)WC_ERR_TRACE(DRBG_NEED_RESEED)
    #define DRBG_CONT_FAILURE (byte)WC_ERR_TRACE(DRBG_CONT_FAILURE)
    #define DRBG_NO_SEED_CB (byte)WC_ERR_TRACE(DRBG_NO_SEED_CB)
    #define WC_DRBG_FAILED (byte)WC_ERR_TRACE(WC_DRBG_FAILED)
    #define WC_DRBG_CONT_FAILED (byte)WC_ERR_TRACE(WC_DRBG_CONT_FAILED)
#endif

#define SEED_SZ           WC_DRBG_SEED_SZ
#define MAX_SEED_SZ       WC_DRBG_MAX_SEED_SZ

/* Verify max gen block len */
#if RNG_MAX_BLOCK_LEN > MAX_REQUEST_LEN
    #error RNG_MAX_BLOCK_LEN is larger than NIST DBRG max request length
#endif

/* the seed device is read through the filesystem API */
#if defined(WC_RNG_SEED_DEVICE) && defined(NO_FILESYSTEM)
    #error WC_RNG_SEED_DEVICE requires filesystem support
#endif

enum {
    drbgInitC     = 0,
    drbgReseed    = 1,
    drbgGenerateW = 2,
    drbgGenerateH = 3,
    drbgInitV     = 4
};

#ifndef NO_SHA256
typedef struct DRBG_internal DRBG_internal;
#endif

#ifdef WOLFSSL_DRBG_SHA512
typedef struct DRBG_SHA512_internal DRBG_SHA512_internal;

static WARN_UNUSED_RESULT int Hash512_DRBG_Reseed(DRBG_SHA512_internal* drbg,
                               const byte* seed, word32 seedSz,
                               const byte* additional, word32 additionalSz);
static WARN_UNUSED_RESULT int Hash512_DRBG_Generate(DRBG_SHA512_internal* drbg,
                                 byte* out, word32 outSz,
                                 const byte* additional, word32 additionalSz);
static WARN_UNUSED_RESULT int Hash512_DRBG_Instantiate(
                                    DRBG_SHA512_internal* drbg,
                                    const byte* seed, word32 seedSz,
                                    const byte* nonce, word32 nonceSz,
                                    const byte* perso, word32 persoSz,
                                    void* heap, int devId);
static int Hash512_DRBG_Uninstantiate(DRBG_SHA512_internal* drbg);
#endif

/* Runtime DRBG disable state.
 * These flags control which DRBG type is used for new WC_RNG instances and
 * may be toggled at runtime (e.g. NSA Suite 2.0 threads disable SHA-256).
 * A mutex protects the check-then-set in disable functions so concurrent
 * calls cannot bypass the mutual-exclusion guard and disable both DRBG types.
 * _InitRng also holds the mutex while reading the flags to get a consistent
 * snapshot, and returns BAD_STATE_E if both are somehow disabled. */
#if !defined(HAVE_SELFTEST) && (!defined(HAVE_FIPS) || FIPS_VERSION3_GE(7,0,0))
#ifndef NO_SHA256
#ifdef WOLFSSL_NO_SHA256_DRBG
static int sha256DrbgDisabled = 1;
#else
static int sha256DrbgDisabled = 0;
#endif /* WOLFSSL_NO_SHA256_DRBG */
#endif /* !NO_SHA256 */
#ifdef WOLFSSL_DRBG_SHA512
static int sha512DrbgDisabled = 0;
#endif /* WOLFSSL_DRBG_SHA512 */


#ifndef SINGLE_THREADED
static wolfSSL_Mutex drbgStateMutex
    WOLFSSL_MUTEX_INITIALIZER_CLAUSE(drbgStateMutex);
#ifndef WOLFSSL_MUTEX_INITIALIZER
enum {
    WC_DRBG_MUTEX_UNINITED,
    WC_DRBG_MUTEX_INITED
};
/* Ports with no static mutex initializer must create drbgStateMutex at run
 * time, so its readiness is tracked here.
 *
 * wc_DrbgState_MutexInit and wc_DrbgState_MutexFree are called only from
 * wolfCrypt_Init() and wolfCrypt_Cleanup(), inside the span serialized by the
 * init-state machine, so this flag is not otherwise synchronized. */
static int drbgStateMutex_inited = WC_DRBG_MUTEX_UNINITED;
#endif /* !defined(WOLFSSL_MUTEX_INITIALIZER) */
#endif /* !defined(SINGLE_THREADED) */


int wc_DrbgState_MutexInit(void)
{
#ifndef SINGLE_THREADED
#ifndef WOLFSSL_MUTEX_INITIALIZER
    if (drbgStateMutex_inited == WC_DRBG_MUTEX_UNINITED) {
        int ret = wc_InitMutex(&drbgStateMutex);
        if (ret != 0) {
            /* flag left unchanged because mutex was not inited */
            return ret;
        }
        drbgStateMutex_inited = WC_DRBG_MUTEX_INITED;
    }

#endif /* !defined(WOLFSSL_MUTEX_INITIALIZER) */
#endif /* !defined(SINGLE_THREADED) */
    return 0;
}

int wc_DrbgState_MutexFree(void)
{
#ifndef SINGLE_THREADED
#ifndef WOLFSSL_MUTEX_INITIALIZER
    if (drbgStateMutex_inited == WC_DRBG_MUTEX_INITED) {
        int ret = wc_FreeMutex(&drbgStateMutex);
        if (ret != 0) {
            /* flag left unchanged because mutex was not freed */
            return ret;
        }
        drbgStateMutex_inited = WC_DRBG_MUTEX_UNINITED;
    }

#endif /* !defined(WOLFSSL_MUTEX_INITIALIZER) */
#endif /* !defined(SINGLE_THREADED) */
    return 0;
}

static WARN_UNUSED_RESULT int LockDrbgState(void)
{
#ifndef SINGLE_THREADED
    return wc_LockMutex(&drbgStateMutex);
#else
    return 0;
#endif
}

static int UnlockDrbgState(void)
{
#ifndef SINGLE_THREADED
    return wc_UnLockMutex(&drbgStateMutex);
#else
    return 0;
#endif
}

#endif /* !HAVE_SELFTEST && (!HAVE_FIPS || FIPS v7+) */

#ifdef WC_RNG_LOCK_ATFORK
/* The lock and its fork handlers live in wc_port.c, outside the FIPS module
 * boundary.  Only the DRBG's reaction to a fork belongs in here. */
static int RngAutoLockInit(WC_RNG* rng)
{
#ifdef WC_RNG_HAVE_LOCK_FULL_MUTEX
    /* A full mutex instance is locked by its caller for the whole call, so
     * the automatic lock leaves that instance alone, as it does without the
     * fork handlers.  Such an instance is not fork covered either. */
    if (rng->flags & WC_RNG_FLAG_FULL_MUTEX)
        return 0;
#endif
    return wc_ForkLock_New(&rng->autoLock, rng->heap);
}

/* Safe on a zeroed WC_RNG that never got a lock. */
static void RngAutoLockFree(WC_RNG* rng)
{
    wc_ForkLock_Free(&rng->autoLock);
}

/* The child's stale DRBG state is dealt with by rng_pid_change_check() on
 * the generate path, which the fork handlers require. */
static int RngAutoLockEnter(WC_RNG* rng)
{
    return wc_ForkLock_Enter(rng->autoLock);
}

static void RngAutoLockExit(WC_RNG* rng)
{
    wc_ForkLock_Exit(rng->autoLock);
}
#elif defined(WC_RNG_HAVE_AUTO_LOCK)
/* Without fork handlers the lock lives in the WC_RNG itself: no heap. */
static int RngAutoLockInit(WC_RNG* rng)
{
#ifdef WC_RNG_HAVE_LOCK_FULL_MUTEX
    /* A full mutex instance is locked by its caller, which holds rng->mutex
     * for the whole call, so the automatic lock leaves that instance alone. */
    if (rng->flags & WC_RNG_FLAG_FULL_MUTEX)
        return 0;
#endif
    if (wc_InitMutex(&rng->mutex) != 0)
        return BAD_MUTEX_E;
    rng->autoLockInited = 1;
    return 0;
}

/* Safe on a zeroed WC_RNG that never got a lock. */
static void RngAutoLockFree(WC_RNG* rng)
{
    if (rng->autoLockInited) {
        (void)wc_FreeMutex(&rng->mutex);
        rng->autoLockInited = 0;
    }
}

/* Cancellation stays off while the lock is held: a reseed reads a device,
 * which is a cancellation point.  wc_port.c owns the platform side. */
static int RngAutoLockEnter(WC_RNG* rng)
{
    int old;
    if (!rng->autoLockInited)
        return 0;
    old = wc_CancelDisable();
    if (wc_LockMutex(&rng->mutex) != 0) {
        wc_CancelRestore(old);
        return BAD_MUTEX_E;
    }
    rng->autoLockCancel = old;
    return 0;
}

static void RngAutoLockExit(WC_RNG* rng)
{
    int old;
    if (!rng->autoLockInited)
        return;
    old = rng->autoLockCancel;   /* read before the unlock hands the slot on */
    (void)wc_UnLockMutex(&rng->mutex);
    wc_CancelRestore(old);
}
#else
#define RngAutoLockEnter(rng) 0
#define RngAutoLockExit(rng)  WC_DO_NOTHING
#endif /* WC_RNG_HAVE_AUTO_LOCK */

static WARN_UNUSED_RESULT int wc_RNG_HealthTestLocal(WC_RNG* rng, int reseed,
                                  void* heap, int devId);

#ifdef WOLFSSL_DRBG_SHA512
static WARN_UNUSED_RESULT int wc_RNG_HealthTest_SHA512_ex_internal(
                                  DRBG_SHA512_internal* drbg,
                                  int reseed, const byte* nonce, word32 nonceSz,
                                  const byte* perso, word32 persoSz,
                                  const byte* seedA, word32 seedASz,
                                  const byte* seedB, word32 seedBSz,
                                  const byte* additionalA, word32 additionalASz,
                                  const byte* additionalB, word32 additionalBSz,
                                  byte* output, word32 outputSz,
                                  void* heap, int devId);
#endif

/* The SHA-256 Hash_DRBG core (Hash_df, Hash_DRBG_*) operates on
 * DRBG_internal, which random.h defines only when SHA-256 is compiled in.
 * Wrap the whole block so a NO_SHA256 + WOLFSSL_DRBG_SHA512 build (the
 * SHA-512-only DRBG configuration) still compiles. The SHA-512 DRBG core
 * lives below in its own #ifdef WOLFSSL_DRBG_SHA512 section. */
#ifndef NO_SHA256

/* Hash Derivation Function */
/* Returns: DRBG_SUCCESS or DRBG_FAILURE */
static WARN_UNUSED_RESULT int Hash_df(DRBG_internal* drbg, byte* out,
                                                  word32 outSz, byte type,
                                                  const byte* inA, word32 inASz,
                                                  const byte* inB, word32 inBSz,
                                                  const byte* inC, word32 inCSz)
{
    int ret = WC_NO_ERR_TRACE(DRBG_FAILURE);
    byte ctr;
    word32 i;
    word32 len;
    word32 bits = (outSz * 8);
#ifdef WOLFSSL_WIDE_BYTE
    byte bitsBuf[4]; /* the 32-bit length as four big-endian octets */
#endif
#ifdef WOLFSSL_SMALL_STACK_CACHE
    wc_Sha256* sha = &drbg->sha256;
#else
    wc_Sha256 sha[1];
#endif
#if defined(WOLFSSL_SMALL_STACK_CACHE)
    byte* digest = drbg->digest_scratch;
#elif defined(WOLFSSL_SMALL_STACK)
    byte* digest;
#else
    byte digest[WC_SHA256_DIGEST_SIZE];
#endif

    if (drbg == NULL) {
        return DRBG_FAILURE;
    }

#if defined(WOLFSSL_SMALL_STACK) && !defined(WOLFSSL_SMALL_STACK_CACHE)
    digest = (byte*)XMALLOC(WC_SHA256_DIGEST_SIZE, drbg->heap,
        DYNAMIC_TYPE_DIGEST);
    if (digest == NULL)
        return DRBG_FAILURE;
#endif

#ifdef WOLFSSL_CHECK_MEM_ZERO
    /* poison so a missed ForceZero on any path is caught by the check */
    XMEMSET(digest, 0xff, WC_SHA256_DIGEST_SIZE);
    wc_MemZero_Add("Hash_df digest", digest, WC_SHA256_DIGEST_SIZE);
#endif

#ifdef WOLFSSL_WIDE_BYTE
    /* A word32 cannot be aliased as an octet stream where a C byte is wider
     * than 8 bits; emit the length as four big-endian octets (shared helper). */
    BytesFromWordsBE32(bitsBuf, &bits, 4);
#elif defined(LITTLE_ENDIAN_ORDER)
    bits = ByteReverseWord32(bits);
#endif
    len = (outSz / OUTPUT_BLOCK_LEN)
        + ((outSz % OUTPUT_BLOCK_LEN) ? 1 : 0);

    ctr = 1;
    for (i = 0; i < len; i++) {
#ifndef WOLFSSL_SMALL_STACK_CACHE
    #if defined(WOLFSSL_ASYNC_CRYPT) || defined(WOLF_CRYPTO_CB)
        ret = wc_InitSha256_ex(sha, drbg->heap, drbg->devId);
    #else
        ret = wc_InitSha256(sha);
    #endif
        if (ret != 0)
            break;
#endif
        ret = wc_Sha256Update(sha, &ctr, sizeof(ctr));
        if (ret == 0) {
            ctr++;
#ifdef WOLFSSL_WIDE_BYTE
            ret = wc_Sha256Update(sha, bitsBuf, sizeof(bitsBuf));
#else
            ret = wc_Sha256Update(sha, (byte*)&bits, sizeof(bits));
#endif
        }

        if (ret == 0) {
            /* churning V is the only string that doesn't have the type added */
            if (type != drbgInitV)
                ret = wc_Sha256Update(sha, &type, sizeof(type));
        }
        if (ret == 0)
            ret = wc_Sha256Update(sha, inA, inASz);
        if (ret == 0) {
            if (inB != NULL && inBSz > 0)
                ret = wc_Sha256Update(sha, inB, inBSz);
        }
        if (ret == 0) {
            if (inC != NULL && inCSz > 0)
                ret = wc_Sha256Update(sha, inC, inCSz);
        }
        if (ret == 0)
            ret = wc_Sha256Final(sha, digest);

#ifdef WOLFSSL_SMALL_STACK_CACHE
        if (ret != 0)
            (void)wc_Sha256Reset(sha);
#else
        wc_Sha256Free(sha);
#endif
        if (ret == 0) {
            if (outSz > OUTPUT_BLOCK_LEN) {
                XMEMCPY(out, digest, OUTPUT_BLOCK_LEN);
                outSz -= OUTPUT_BLOCK_LEN;
                out += OUTPUT_BLOCK_LEN;
            }
            else {
                XMEMCPY(out, digest, outSz);
            }
        }
        else {
            break;
        }
    }

    ForceZero(digest, WC_SHA256_DIGEST_SIZE);
    /* Explicit check only where the buffer is NOT XFREEd (XFREE auto-checks):
     * the stack build and the small-stack-cache build (drbg member). */
#if (!defined(WOLFSSL_SMALL_STACK) || defined(WOLFSSL_SMALL_STACK_CACHE)) && \
    defined(WOLFSSL_CHECK_MEM_ZERO)
    wc_MemZero_Check(digest, WC_SHA256_DIGEST_SIZE);
#endif

#if defined(WOLFSSL_SMALL_STACK) && !defined(WOLFSSL_SMALL_STACK_CACHE)
    XFREE(digest, drbg->heap, DYNAMIC_TYPE_DIGEST);
#endif

#ifdef WC_VERBOSE_RNG
    if (ret != 0)
        WOLFSSL_DEBUG_PRINTF("ERROR: %s failed with err = %d", __func__,
                             ret);
#endif

    return (ret == 0) ? DRBG_SUCCESS : DRBG_FAILURE;
}

/* Returns: DRBG_SUCCESS or DRBG_FAILURE.  No state mutation on failure. */
static WARN_UNUSED_RESULT int Hash256_DRBG_Reseed(DRBG_internal* drbg,
                               const byte* seed,
                               word32 seedSz, const byte* additional,
                               word32 additionalSz)
{
    int ret;
    WC_DECLARE_VAR(newV_C, byte, DRBG_SEED_LEN * 2, 0);
    byte *newV, *newC;

    if (drbg == NULL) {
        return DRBG_FAILURE;
    }

#ifdef WOLFSSL_SMALL_STACK_CACHE
    newV_C = drbg->seed_scratch;
#else
    WC_ALLOC_VAR_EX(newV_C, byte, DRBG_SEED_LEN * 2, drbg->heap,
        DYNAMIC_TYPE_TMP_BUFFER, return DRBG_FAILURE);
#endif
    XMEMSET(newV_C, 0, DRBG_SEED_LEN * 2);
#ifdef WOLFSSL_CHECK_MEM_ZERO
    wc_MemZero_Add("Hash256_DRBG_Reseed newV_C", newV_C, DRBG_SEED_LEN * 2);
#endif

    newV = newV_C;
    newC = newV + DRBG_SEED_LEN;

    ret = Hash_df(drbg, newV, DRBG_SEED_LEN, drbgReseed,
                drbg->V, sizeof(drbg->V), seed, seedSz,
                additional, additionalSz);
    if (ret == DRBG_SUCCESS) {
        ret = Hash_df(drbg, newC, DRBG_SEED_LEN, drbgInitC, newV,
                                    DRBG_SEED_LEN, NULL, 0, NULL, 0);
    }
    if (ret == DRBG_SUCCESS) {
        XMEMCPY(drbg->V, newV, DRBG_SEED_LEN);
        XMEMCPY(drbg->C, newC, DRBG_SEED_LEN);
        drbg->reseedCtr = 1;
    }

    ForceZero(newV_C, DRBG_SEED_LEN * 2);
#if (!defined(WOLFSSL_SMALL_STACK) || defined(WOLFSSL_SMALL_STACK_CACHE)) && \
    defined(WOLFSSL_CHECK_MEM_ZERO)
    wc_MemZero_Check(newV_C, DRBG_SEED_LEN * 2);
#endif

#ifndef WOLFSSL_SMALL_STACK_CACHE
    WC_FREE_VAR_EX(newV_C, drbg->heap, DYNAMIC_TYPE_TMP_BUFFER);
#endif

    return ret;
}

#endif /* !NO_SHA256 */

#ifdef WC_RNG_HAVE_NEXT_SEED
/* Purge the credited next-seed aperture.  A plain store would race an in-flight
 * producer: the producer's publish must lose against a purge, never the
 * reverse, or material generated before a state-invalidation event could
 * surface READY after it -- exactly the resurrection the provenance guarantee
 * forbids.  A producer mid-fill (PRODUCING) owns the buffer, so the purge only
 * repaints the sentinel (PRODUCING -> PURGED); the producer's failed
 * publish-CAS observes the repaint and reopens the aperture EMPTY (see
 * NextSeedProducerRelease()) -- the sentinel alone suppresses the pre-event
 * material; abandoned seed-aperture buffers are zeroized as explained below.
 * All other states purge directly to EMPTY.  (The uncredited stir aperture
 * keeps its plain-store purge: stirs carry no claims, so resurrection there is
 * benign by the three-no-ops doctrine.)
 *
 * Zeroization doctrine for purges: abandonment here is event-driven (fork,
 * VM clone/resume, credited reseed), and the event that abandons bytes in
 * this lineage is the same event that created a sibling lineage that may
 * consume its identical copy of them.  Abandoned-here can be consumed-there,
 * so purged material is treated as CSP and wiped -- under ownership only:
 * READY or parked-fill words are claimed _CONSUMING first (the same CAS a
 * consumer uses; producers claim only non-negative words, so the claim
 * cannot collide), then wiped, then reopened EMPTY.  A _CONSUMING holder's
 * material is left to that consumer's own burn-before-release, and a
 * _PRODUCING holder's to its unwind (see NextSeedProducerRelease()).
 * Contrast the health-test burn arm, which stays sentinel-only: RCT/APT
 * are deterministic on the bytes, so every sibling rejects the same
 * material identically and no lineage can have consumed it.
 */
static WARN_UNUSED_RESULT int NextSeedPurge(wolfSSL_Atomic_Int *lenp,
                                            byte *seed_buf,
                                            word32 seed_buf_sz)
{
    int ret;
    WC_ATOMIC_INT_ARG cur_len, want_len;

    WC_CAS_WITH_RETRY_BEGIN_INIT_CUR(lenp, cur_len, ret) {
        if (cur_len == WC_DRBG_NEXT_SEED_PURGED)
            return ALREADY_E; /* already handed off to a producer's unwind. */
        if ((cur_len == WC_DRBG_NEXT_SEED_READY) || (cur_len > 0)) {
            /* Published or parked bytes with no owner: claim, wipe as
             * owner, reopen. */
            WC_CAS_WITH_RETRY_LOOP_FOREVER(wolfSSL_Atomic_Int_CompareExchange,
                                          lenp, cur_len,
                                          WC_DRBG_NEXT_SEED_CONSUMING, ret);
            ForceZero(seed_buf, seed_buf_sz);
            WOLFSSL_ATOMIC_STORE(*lenp, WC_DRBG_NEXT_SEED_EMPTY);
        }
        else {
            want_len = (cur_len == WC_DRBG_NEXT_SEED_PRODUCING) ?
                WC_DRBG_NEXT_SEED_PURGED : WC_DRBG_NEXT_SEED_EMPTY;
            WC_CAS_WITH_RETRY_LOOP_FOREVER(wolfSSL_Atomic_Int_CompareExchange,
                                          lenp, cur_len, want_len, ret);
        }
    } WC_CAS_WITH_RETRY_END;

    /* percolate the CAS result -- if the loop was aborted by user logic, the
     * caller needs to know that the purge failed. */
    return ret;
}

/* Release a producer claim (PRODUCING) on the credited aperture,
 * installing val (a fill offset, the full length, READY, or EMPTY).
 * Returns 0 on release, else BUSY_E: the release CAS can fail for
 * exactly one reason -- a concurrent NextSeedPurge() repainted the
 * claim PURGED (producers cannot claim a PRODUCING word, consumers
 * only exchange from READY, and the purge is the sole writer against
 * a claim).  The producer's material then predates the invalidation
 * event and must not surface: the aperture reopens EMPTY, which is
 * the whole suppression -- an EMPTY aperture is never consumed, and
 * the next fill overwrites from offset zero.  The bytes themselves are
 * wiped before the reopen, while this producer still owns the buffer:
 * the purge that repainted the claim marks an event that created a
 * sibling lineage, and the sibling's copy of a completed fill may be
 * consumed there (see the doctrine at NextSeedPurge()). */
static int NextSeedProducerRelease(wolfSSL_Atomic_Int *lenp,
                                   byte *seed_buf, word32 seed_buf_sz,
                                   WC_ATOMIC_INT_ARG val)
{
    WC_ATOMIC_INT_ARG expected = WC_DRBG_NEXT_SEED_PRODUCING;
    if (wolfSSL_Atomic_Int_CompareExchange(lenp, &expected, val))
        return 0;
    ForceZero(seed_buf, seed_buf_sz);
    WOLFSSL_ATOMIC_STORE(*lenp, WC_DRBG_NEXT_SEED_EMPTY);
    return BUSY_E;
}
#endif /* WC_RNG_HAVE_NEXT_SEED */

/* in_bracketed_consume: nonzero when the caller feeds this reseed from its own
 * _CONSUMING claim on the credited aperture (wc_RNG_DRBG_NextSeedNow_Nonce()).
 * The invalidated-entry purges below must then exempt that aperture: purging
 * it would steal the caller's claim and defeat its release CAS, converting
 * the caller's own recovery into a false epoch violation.  An external
 * (event) purge still repaints the claim, which is exactly what the
 * caller's release CAS exists to detect. */
static WARN_UNUSED_RESULT int Hash_DRBG_Reseed(WC_RNG* rng, const byte* seed,
                            word32 seedSz,
                            const byte* additional, word32 additionalSz,
                            int in_bracketed_consume)
{
    int ret;
#ifdef WC_RNG_HAVE_LOCK
    WC_RNG_lock_arg_t cur_lock;
#endif

    if (rng == NULL)
        return BAD_FUNC_ARG;

#ifdef WC_RNG_HAVE_LOCK
    cur_lock = WOLFSSL_ATOMIC_LOAD(rng->lock);
#endif

#ifdef WC_RNG_HAVE_LOCK
    /* Never allow an undersized seed to clear an invalidated state. */
    if ((cur_lock & WC_RNG_LOCK_ENTROPY_INVALIDATED) &&
        (seedSz < WC_DRBG_SEED_SZ))
    {
        /* Short-circuit return in case the _RECOVERING mutex below would have
         * failed. */
        return NEEDS_RECOVERY_E;
    }

    /* Iff _ENTROPY_INVALIDATED, assert the _ENTROPY_RECOVERING bit now -- if we
     * are re-invalidated in the meantime, it will have been cleared by the
     * invalidation at exit time, signaling that we are still invalidated. */

    WC_CAS_WITH_RETRY_BEGIN(&rng->lock, cur_lock, ret) {
        if (! (cur_lock & WC_RNG_LOCK_ENTROPY_INVALIDATED)) {
            /* Not invalidated -- no recovery mutex needed.  Explicit
             * success: BEGIN initializes ret to a failure code. */
            ret = 0;
            break;
        }
        if (cur_lock & WC_RNG_LOCK_ENTROPY_RECOVERING) {
            /* Must short-circuit return here, so that we don't improperly clear
             * the _RECOVERING bit. */
            return BUSY_E;
        }
        WC_CAS_WITH_RETRY_LOOP_FOREVER(wolfSSL_Atomic_Uint_CompareExchange,
                                      &rng->lock, cur_lock,
                                      cur_lock | WC_RNG_LOCK_ENTROPY_RECOVERING,
                                      ret);
        /* We now have the _RECOVERING mutex -- record that fact. */
        cur_lock |= WC_RNG_LOCK_ENTROPY_RECOVERING;
    } WC_CAS_WITH_RETRY_END;
    if (ret != 0) {
        /* Aborted acquire (a port's retry clause): the lock word is
         * untouched and no state has moved -- bail before the purges,
         * which must not run unserialized against a concurrent
         * recovery. */
        return ret;
    }
#endif /* WC_RNG_HAVE_LOCK */

#ifdef WC_RNG_HAVE_POOL
    /* Purge the pool when recovering from invalidation, or if reseeding without
     * locks (i.e. without an internal mechanism for tracking invalidation).
     *
     * The reseed counter tracks generates since the last reseed, and every
     * pooled byte is itself a generate that incremented it. So the pool's
     * contents are within the budget the counter enforces -- indeed they were
     * authorized by the same accounting that later demanded the
     * reseed. Discarding them treats output as retroactively over-budget when
     * it was under-budget when produced.
     */
    #ifdef WC_RNG_HAVE_LOCK
    if (cur_lock & WC_RNG_LOCK_ENTROPY_INVALIDATED)
    #endif
    {
        ret = PoolPurge(rng);
        if ((ret != 0) &&
            (ret != WC_NO_ERR_TRACE(ALREADY_E)))
        {
            goto out;
        }
    }
#endif /* WC_RNG_HAVE_POOL */

#ifndef NO_SHA256
    if (rng->drbgType == WC_DRBG_SHA256) {
        DRBG_internal* drbg = (DRBG_internal *)rng->drbg;

        if (drbg == NULL) {
        #if defined(HAVE_INTEL_RDSEED) || defined(HAVE_INTEL_RDRAND)
            if (IS_INTEL_RDRAND(intel_flags)) {
                /* using RDRAND not DRBG, so return success */
                ret = 0;
                goto out;
            }
        #endif
            ret = BAD_FUNC_ARG;
            goto out;
        }

#if defined(WC_RNG_HAVE_LOCK) && defined(WC_RNG_HAVE_NEXT_SEED)
        if ((cur_lock & WC_RNG_LOCK_ENTROPY_INVALIDATED) &&
            (! in_bracketed_consume))
        {
            ret = NextSeedPurge(&drbg->nextSeedLen, drbg->nextSeed,
                                (word32)sizeof(drbg->nextSeed));
            if ((ret != 0) &&
                (ret != WC_NO_ERR_TRACE(ALREADY_E)))
            {
                goto out;
            }
            /* the uncredited stir aperture is purged too, for provenance
             * uniformity; best-effort (an in-flight depositor may
             * resurrect a partial fill -- benign, stirs carry no
             * divergence burden), and never zeroized (racy, and
             * interleaved entropy of compatible provenance is harmless).
             */
            WOLFSSL_ATOMIC_STORE(rng->nextStirLen,
                                 WC_DRBG_NEXT_SEED_EMPTY);
        }
#else
        (void)in_bracketed_consume;
#endif

        ret = Hash256_DRBG_Reseed(drbg, seed, seedSz, additional, additionalSz);
#ifdef WC_RNG_DEBUG_STATS
        if (ret == 0) {
            ++rng->_stats_reseeds;
        }
#endif
        goto out;
    }
#endif

#ifdef WOLFSSL_DRBG_SHA512
    if (rng->drbgType == WC_DRBG_SHA512) {
        DRBG_SHA512_internal* drbg512 =
            (DRBG_SHA512_internal *)rng->drbg512;

        if (drbg512 == NULL) {
        #if defined(HAVE_INTEL_RDSEED) || defined(HAVE_INTEL_RDRAND)
            if (IS_INTEL_RDRAND(intel_flags)) {
                /* using RDRAND not DRBG, so return success */
                ret = 0;
                goto out;
            }
        #endif
            ret = BAD_FUNC_ARG;
            goto out;
        }

#if defined(WC_RNG_HAVE_LOCK) && defined(WC_RNG_HAVE_NEXT_SEED)
        if ((cur_lock & WC_RNG_LOCK_ENTROPY_INVALIDATED) &&
            (! in_bracketed_consume))
        {
            ret = NextSeedPurge(&drbg512->nextSeedLen, drbg512->nextSeed,
                                (word32)sizeof(drbg512->nextSeed));
            if ((ret != 0) &&
                (ret != WC_NO_ERR_TRACE(ALREADY_E)))
            {
                goto out;
            }
            /* see the SHA-256 arm re best-effort and no-zeroize. */
            WOLFSSL_ATOMIC_STORE(rng->nextStirLen,
                                 WC_DRBG_NEXT_SEED_EMPTY);
        }
#endif

        ret = Hash512_DRBG_Reseed(drbg512, seed, seedSz,
                                  additional, additionalSz);
#ifdef WC_RNG_DEBUG_STATS
        if (ret == 0) {
            ++rng->_stats_reseeds;
        }
#endif
        goto out;
    }
#endif

    /* No DRBG type matched; if using RDRAND, that's OK */
    #if defined(HAVE_INTEL_RDSEED) || defined(HAVE_INTEL_RDRAND)
    if (IS_INTEL_RDRAND(intel_flags)) {
        /* using RDRAND not DRBG, so return success */
        ret = 0;
        goto out;
    }
    #endif

    ret = WRONG_TYPE_OBJECT_E;

    out:

#ifdef WC_RNG_HAVE_LOCK
    /* The _RECOVERING bit functions as a mutex -- if it's set here, *we*
     * set it, and must clear it.
     *
     * If we were invalidated on entry, and reseed succeeded, and provided we
     * weren't re-invalidated in the meantime, clear the _INVALIDATED bit
     * alongside the _RECOVERING bit.
     *
     * Otherwise, just clear the _RECOVERING bit (releasing the recovery mutex),
     * and return with the success or failure code from above.
     */
    if ((ret == 0) && (cur_lock & WC_RNG_LOCK_ENTROPY_INVALIDATED)) {
        WC_CAS_WITH_RETRY_BEGIN(&rng->lock, cur_lock, ret) {
            if (! (cur_lock & WC_RNG_LOCK_ENTROPY_RECOVERING)) {
                ret = NEEDS_RECOVERY_E;
                break;
            }
            WC_CAS_WITH_RETRY_LOOP_FOREVER(
                wolfSSL_Atomic_Uint_CompareExchange, &rng->lock, cur_lock,
                cur_lock & ~(WC_RNG_LOCK_ENTROPY_INVALIDATED |
                             WC_RNG_LOCK_ENTROPY_RECOVERING),
                ret);
        } WC_CAS_WITH_RETRY_END;
        if ((ret != 0) && (ret != WC_NO_ERR_TRACE(NEEDS_RECOVERY_E))) {
            /* Aborted clear (a port's retry clause) strands _RECOVERING with no
             * in-band path back: every future recovery would refuse BUSY_E.
             * Condemn -- in kernel, DRBG_FAILED has an automated exit (the
             * entropy daemon's recovery pass), and the owner can always reinit.
             * A wedged mutex bit would have no visible indication that reinit
             * is required.
             */
            rng->status = DRBG_FAILED;
        }
    }
    else if (cur_lock & WC_RNG_LOCK_ENTROPY_RECOVERING) {
        /* ret carries the reseed's status here and must survive, so the
         * release gets its own result variable. */
        int release_ret;
        WC_CAS_WITH_RETRY_BEGIN(&rng->lock, cur_lock, release_ret) {
            WC_CAS_WITH_RETRY_LOOP_FOREVER(
                wolfSSL_Atomic_Uint_CompareExchange, &rng->lock, cur_lock,
                cur_lock & ~WC_RNG_LOCK_ENTROPY_RECOVERING, release_ret);
        } WC_CAS_WITH_RETRY_END;
        if (release_ret != 0) {
            /* Same stranded-_RECOVERING condemnation as the clear arm
             * above; the reseed's own status still wins the return. */
            rng->status = DRBG_FAILED;
            if (ret == 0)
                ret = release_ret;
        }
    }
#endif /* WC_RNG_HAVE_LOCK */

    return ret;
}

int wc_RNG_DRBG_Reseed_Nonce(WC_RNG* rng, const byte* seed, word32 seedSz,
                             const byte *nonce, word32 nonceSz)
{
    int ret;

    if (rng == NULL || seed == NULL) {
        return BAD_FUNC_ARG;
    }

    /* Hash_df() skips a NULL input regardless of its stated length, so
     * without this the caller's additional input would be dropped and
     * success reported.  Matches _InitRng() and ReseedRBGC(). */
    if ((nonce == NULL) && (nonceSz > 0))
        return BAD_FUNC_ARG;

    ret = rng_lock_required_check(rng);
    if (ret != 0)
        return ret;

    /* These checks read state a generate writes under the lock, so the lock
     * comes first.  The internal reseed paths already hold it. */
    ret = RngAutoLockEnter(rng);
    if (ret != 0)
        return ret;

    /* A condemned instance does not accept a credited reseed: DRBG_FAILED's
     * designed exit is wc_FreeRng()/wc_InitRng() (or the daemon's recovery
     * pass), not in-place resurrection that would reset the counter, purge
     * the pool, and clear quarantine on unvetted authority. */
    if (rng->status != DRBG_OK) {
        ret = RNG_FAILURE_E;
        goto out;
    }

#ifdef WC_RNG_HAVE_LOCK
    /* Never allow an undersized seed to clear an invalidated state, and if
     * invalidated, always assume potentially primary seed data -- test it with
     * wc_RNG_TestSeed(). */
    if (WOLFSSL_ATOMIC_LOAD(rng->lock) & WC_RNG_LOCK_ENTROPY_INVALIDATED) {
        if (seedSz < WC_DRBG_SEED_SZ) {
            ret = NEEDS_RECOVERY_E;
            goto out;
        }
        ret = wc_RNG_TestSeed(seed, seedSz);
        if (ret != 0)
            goto out;
    }
#endif /* WC_RNG_HAVE_LOCK */

    ret = Hash_DRBG_Reseed(rng, seed, seedSz, nonce, nonceSz,
                           0 /* in_bracketed_consume */);
#ifdef WC_RNG_HAVE_RBGC
    if (ret == 0) {
        /* User-supplied entropy is of unknown provenance.  In RBGC builds,
         * represent that fact using WC_RNG_RBGC_USER_SEED_STRATUM, preventing confusion with RNGs seeded by the ESV . */
        rng->RBGCStratum = WC_RNG_RBGC_USER_SEED_STRATUM;
    }
#endif

    out:

    RngAutoLockExit(rng);
    return ret;
}

int wc_RNG_DRBG_Reseed(WC_RNG* rng, const byte* seed, word32 seedSz) {
    return wc_RNG_DRBG_Reseed_Nonce(rng, seed, seedSz, NULL, 0);
}

#ifdef WC_RNG_HAVE_RBGC

int wc_RNG_DRBG_GetRBGCStratum(const WC_RNG* rng)
{
    if (rng)
        return rng->RBGCStratum;
    else
        return BAD_FUNC_ARG;
}

#ifdef WC_RNG_HAVE_NEXT_SEED
int wc_RNG_DRBG_GetNextSeedRBGCStratum(const WC_RNG* rng)
{
    if (rng == NULL)
        return BAD_FUNC_ARG;

    /* Race-free via the NextSeed aperture protocol.  If called with rng locked,
     * and ->nextSeedLen == WC_DRBG_NEXT_SEED_READY, then competing producers
     * and consumers are all excluded, unambiguously marking
     * ->nextSeedRBGCStratum as strictly reliable and stable.  nextSeedLen
     * functions as the synchronizer -- the producer writes
     * ->nextSeedRBGCStratum before publishing WC_DRBG_NEXT_SEED_READY to
     * nextSeedLen with release semantics.
     */

#ifndef NO_SHA256
    if ((rng->drbgType == WC_DRBG_SHA256) && (rng->drbg != NULL)) {
        if (WOLFSSL_ATOMIC_LOAD(((const DRBG_internal*)rng->drbg)->nextSeedLen)
            != WC_DRBG_NEXT_SEED_READY)
        {
            return NOT_READY_E;
        }
        else
            return ((const DRBG_internal *)rng->drbg)->nextSeedRBGCStratum;
    }
#endif
#ifdef WOLFSSL_DRBG_SHA512
    if ((rng->drbgType == WC_DRBG_SHA512) && (rng->drbg512 != NULL)) {
        if (WOLFSSL_ATOMIC_LOAD(((const DRBG_SHA512_internal*)rng->drbg512)->nextSeedLen)
            != WC_DRBG_NEXT_SEED_READY)
        {
            return NOT_READY_E;
        }
        else
            return ((const DRBG_SHA512_internal *)rng->drbg512)->nextSeedRBGCStratum;
    }
#endif

    return BAD_FUNC_ARG;
}
#endif /* WC_RNG_HAVE_NEXT_SEED */

#endif /* WC_RNG_HAVE_RBGC */

/* Read-only accessor for the DRBG reseed counter.  When no DRBG is
 * instantiated (see wc_RNG_DRBG_Present()) there is no counter; *reseedCtr
 * is set to 0 -- never due for reseed -- and 0 is returned. */
int wc_RNG_DRBG_GetReseedCtr(const WC_RNG* rng,
                             wc_drbg_reseed_ctr_t* reseedCtr)
{
    if ((rng == NULL) || (reseedCtr == NULL))
        return BAD_FUNC_ARG;
    if (! wc_RNG_DRBG_Present(rng))
        return WRONG_TYPE_OBJECT_E;
    if (rng->status != DRBG_OK)
        return BAD_STATE_E;
#ifndef NO_SHA256
    if ((rng->drbgType == WC_DRBG_SHA256) && (rng->drbg != NULL)) {
        *reseedCtr = ((const DRBG_internal *)rng->drbg)->reseedCtr;
        return 0;
    }
#endif
#ifdef WOLFSSL_DRBG_SHA512
    if ((rng->drbgType == WC_DRBG_SHA512) && (rng->drbg512 != NULL)) {
        *reseedCtr = (wc_drbg_reseed_ctr_t)
            ((const DRBG_SHA512_internal *)rng->drbg512)->reseedCtr;
        return 0;
    }
#endif
    return BAD_FUNC_ARG;
}

#if defined(WC_RESEED_INTERVAL) && !defined(WORD64_AVAILABLE)
    wc_static_assert((WC_RESEED_INTERVAL) <= 0xFFFFFFFFUL);
#endif

/* Mark rng due for reseed: the next generate operation reseeds from the
 * module's built-in or registered seed source before producing output (see also
 * wc_RNG_DRBG_Reseed_Now()).  This can only shorten the current seed's
 * remaining lifetime, never extend it.  When no DRBG is instantiated (RDRAND et
 * al.) commanded reseed is not supported and the call returns
 * WRONG_TYPE_OBJECT_E. */
/* Every public entry below locks the instance, with a _local core for the
 * generate path, which already holds the lock.
 *
 * Why they lock at all: they mutate the same DRBG state a generate does.
 * Unlocked, a second thread reads and writes the reseed counter and the hash
 * context mid-update, which ThreadSanitizer reports as a data race: 48 of them
 * before this change, none after.  Nothing crashes and the output still looks
 * random, which is what makes it easy to ship by mistake.
 */
static WARN_UNUSED_RESULT int wc_RNG_DRBG_ScheduleReseed_local(WC_RNG* rng)
{
    if (rng == NULL)
        return BAD_FUNC_ARG;
#ifndef NO_SHA256
    if ((rng->drbgType == WC_DRBG_SHA256) && (rng->drbg != NULL)) {
        ((DRBG_internal *)rng->drbg)->reseedCtr =
            (wc_drbg_reseed_ctr_t)WC_RESEED_INTERVAL;
        return 0;
    }
#endif
#ifdef WOLFSSL_DRBG_SHA512
    if ((rng->drbgType == WC_DRBG_SHA512) && (rng->drbg512 != NULL)) {
        ((DRBG_SHA512_internal *)rng->drbg512)->reseedCtr =
            (word64)WC_RESEED_INTERVAL;
        return 0;
    }
#endif
    return WRONG_TYPE_OBJECT_E;
}

int wc_RNG_DRBG_ScheduleReseed(WC_RNG* rng)
{
    int ret;

    if (rng == NULL)
        return BAD_FUNC_ARG;
    ret = RngAutoLockEnter(rng);
    if (ret != 0)
        return ret;
    ret = wc_RNG_DRBG_ScheduleReseed_local(rng);
    RngAutoLockExit(rng);
    return ret;
}

/* Generic byte-array helper -- shared by both SHA-256 and SHA-512 DRBG
 * cores. Lives outside the NO_SHA256 guard so SHA-512-only builds
 * still build. */
static WC_INLINE void array_add_one(byte* data, word32 dataSz)
{
    int i;
    for (i = (int)dataSz - 1; i >= 0; i--) {
        data[i] = WC_OCTET(data[i] + 1);
        if (data[i] != 0) break;
    }
}

#ifndef NO_SHA256 /* re-open SHA-256 Hash_DRBG core */

/* Returns: DRBG_SUCCESS or DRBG_FAILURE */
static WARN_UNUSED_RESULT int Hash_gen(DRBG_internal* drbg, byte* out,
                                       word32 outSz, const byte* V)
{
    int ret = WC_NO_ERR_TRACE(DRBG_FAILURE);
    word32 i;
    word32 len;
#if defined(WOLFSSL_SMALL_STACK_CACHE)
    wc_Sha256* sha = &drbg->sha256;
    byte* data = drbg->seed_scratch; /* Note, top half of seed_scratch is used
                                      * by Hash_DRBG_Generate(). */
    byte* digest = drbg->digest_scratch;
#elif defined(WOLFSSL_SMALL_STACK)
    wc_Sha256 sha[1];
    byte* data = NULL;
    byte* digest = NULL;
#else
    wc_Sha256 sha[1];
    byte data[DRBG_SEED_LEN];
    byte digest[WC_SHA256_DIGEST_SIZE];
#endif

    if (drbg == NULL) {
        return DRBG_FAILURE;
    }

#if defined(WOLFSSL_SMALL_STACK) && !defined(WOLFSSL_SMALL_STACK_CACHE)
    data = (byte*)XMALLOC(DRBG_SEED_LEN, drbg->heap, DYNAMIC_TYPE_TMP_BUFFER);
    digest = (byte*)XMALLOC(WC_SHA256_DIGEST_SIZE, drbg->heap,
        DYNAMIC_TYPE_DIGEST);
    if (data == NULL || digest == NULL) {
        XFREE(digest, drbg->heap, DYNAMIC_TYPE_DIGEST);
        XFREE(data, drbg->heap, DYNAMIC_TYPE_TMP_BUFFER);
        return DRBG_FAILURE;
    }
#endif

    /* Special case: outSz is 0 and out is NULL (Hash_DRBG_StirGenerate()): run
     * a single Hashgen iteration with the block discarded, so the caller gets
     * Generate's V-advance side effects without emitting output.  This
     * preserves standard SP 800-90A sequencing, while presenting call semantics
     * that are convenient for the stir. */
    if (outSz == 0) {
        outSz = 1;
    }

    len = (outSz / OUTPUT_BLOCK_LEN) + ((outSz % OUTPUT_BLOCK_LEN) ? 1 : 0);

    XMEMCPY(data, V, DRBG_SEED_LEN);
#ifdef WOLFSSL_CHECK_MEM_ZERO
    wc_MemZero_Add("Hash_gen data", data, DRBG_SEED_LEN);
#endif
    for (i = 0; i < len; i++) {
#ifndef WOLFSSL_SMALL_STACK_CACHE
    #if defined(WOLFSSL_ASYNC_CRYPT) || defined(WOLF_CRYPTO_CB)
        ret = wc_InitSha256_ex(sha, drbg->heap, drbg->devId);
    #else
        ret = wc_InitSha256(sha);
    #endif
        if (ret == 0)
#endif
            ret = wc_Sha256Update(sha, data, DRBG_SEED_LEN);
        if (ret == 0)
            ret = wc_Sha256Final(sha, digest);
#ifdef WOLFSSL_SMALL_STACK_CACHE
        if (ret != 0)
            (void)wc_Sha256Reset(sha);
#else
        wc_Sha256Free(sha);
#endif

        if (ret == 0) {
            if (out != NULL && outSz != 0) {
                if (outSz >= OUTPUT_BLOCK_LEN) {
                    XMEMCPY(out, digest, OUTPUT_BLOCK_LEN);
                    outSz -= OUTPUT_BLOCK_LEN;
                    out += OUTPUT_BLOCK_LEN;
                    array_add_one(data, DRBG_SEED_LEN);
                }
                else {
                    XMEMCPY(out, digest, outSz);
                    outSz = 0;
                }
            }
        }
        else {
            /* wc_Sha256Update or wc_Sha256Final returned error */
            break;
        }
    }
    ForceZero(data, DRBG_SEED_LEN);
#if (!defined(WOLFSSL_SMALL_STACK) || defined(WOLFSSL_SMALL_STACK_CACHE)) && \
    defined(WOLFSSL_CHECK_MEM_ZERO)
    wc_MemZero_Check(data, DRBG_SEED_LEN);
#endif

#ifndef WOLFSSL_SMALL_STACK_CACHE
    WC_FREE_VAR_EX(digest, drbg->heap, DYNAMIC_TYPE_DIGEST);
    WC_FREE_VAR_EX(data, drbg->heap, DYNAMIC_TYPE_TMP_BUFFER);
#endif

    #ifdef WC_VERBOSE_RNG
    if ((ret != DRBG_SUCCESS) && (ret != WC_NO_ERR_TRACE(DRBG_FAILURE))) {
        /* Note, if we're just going to return DRBG_FAILURE to the caller, then
         * there's no point printing it out here because (1) the lower-level
         * code that was remapped to DRBG_FAILURE already got printed before the
         * remapping, so a DRBG_FAILURE message would just be spamming the log,
         * and (2) the caller will actually see the DRBG_FAILURE code, and is
         * free to (and probably will) log it itself.
         */
        WOLFSSL_DEBUG_PRINTF("ERROR: Hash_gen failed with err %d.", ret);
    }
    #endif

    return (ret == 0) ? DRBG_SUCCESS : DRBG_FAILURE;
}

#endif /* !NO_SHA256 - close to expose array_add to SHA-512 below */

/* Generic multi-byte add. Shared by SHA-256 and SHA-512 DRBG cores;
 * lives outside the NO_SHA256 guard so SHA-512-only builds still link. */
static WC_INLINE void array_add(byte* d, word32 dLen, const byte* s, word32 sLen)
{
    if (dLen > 0 && sLen > 0 && dLen >= sLen) {
        int sIdx, dIdx;
        word16 carry = 0;

        dIdx = (int)dLen - 1;
        for (sIdx = (int)sLen - 1; sIdx >= 0; sIdx--) {
            carry = (word16)(carry + d[dIdx] + s[sIdx]);
            d[dIdx] = WC_OCTET(carry);
            carry >>= 8;
            dIdx--;
        }

        for (; dIdx >= 0; dIdx--) {
            carry = (word16)(carry + d[dIdx]);
            d[dIdx] = WC_OCTET(carry);
            carry >>= 8;
        }
    }
}

#ifndef NO_SHA256 /* re-open SHA-256 Hash_DRBG core */

/* Returns: DRBG_SUCCESS, DRBG_NEED_RESEED, or DRBG_FAILURE.  DRBG state is
 * always consistent upon return, whether success or failure. */
static WARN_UNUSED_RESULT int Hash_DRBG_Generate(DRBG_internal* drbg,
                              byte* out, word32 outSz,
                              const byte* additional, word32 additionalSz)
{
    int ret;
#ifdef WOLFSSL_SMALL_STACK_CACHE
    wc_Sha256* sha = &drbg->sha256;
#else
    wc_Sha256 sha[1];
#endif
    byte type;
#ifdef WORD64_AVAILABLE
    word64 reseedCtr;
#else
    word32 reseedCtr;
#endif
#ifdef WOLFSSL_WIDE_BYTE
    byte ctrBuf[8]; /* reseed counter as big-endian octets */
#endif
    byte *thisV = NULL;
    WC_DECLARE_VAR(shadowV, byte, DRBG_SEED_LEN, 0);

    if (drbg == NULL) {
        return DRBG_FAILURE;
    }

    if (drbg->reseedCtr >= WC_RESEED_INTERVAL) {
    #if (defined(DEBUG_WOLFSSL) || defined(DEBUG_DRBG_RESEEDS)) && \
        defined(WOLFSSL_DEBUG_PRINTF)
        WOLFSSL_DEBUG_PRINTF("DRBG reseed triggered, reseedCtr == %lu",
                (unsigned long)drbg->reseedCtr);
    #endif
        return DRBG_NEED_RESEED;
    }
    else {
    #if defined(WOLFSSL_SMALL_STACK_CACHE)
        byte* digest = drbg->digest_scratch;
    #elif defined(WOLFSSL_SMALL_STACK)
        byte* digest = (byte*)XMALLOC(WC_SHA256_DIGEST_SIZE, drbg->heap,
            DYNAMIC_TYPE_DIGEST);
        if (digest == NULL)
            return DRBG_FAILURE;
    #else
        byte digest[WC_SHA256_DIGEST_SIZE];
    #endif

    #ifdef WOLFSSL_CHECK_MEM_ZERO
        /* baseline 0 (not 0xff): a pre-write early exit on this path checks
         * digest, so it must read zero.  Registered across the whole generate;
         * every exit below force-zeros+checks (or XFREEs) it. */
        XMEMSET(digest, 0, WC_SHA256_DIGEST_SIZE);
        wc_MemZero_Add("Hash_DRBG_Generate digest", digest,
            WC_SHA256_DIGEST_SIZE);
    #endif

        type = drbgGenerateH;
        reseedCtr = drbg->reseedCtr;

        /* SP 800-90A 10.1.1.4 step 2: if additional_input != Null,
         * w = Hash(0x02 || V || additional_input), V = (V + w) mod 2^seedlen */
        if (additional != NULL && additionalSz > 0) {
            byte addType = drbgGenerateW;
#ifndef WOLFSSL_SMALL_STACK_CACHE
            ret = 0;
            WC_ALLOC_VAR_EX(shadowV, byte, DRBG_SEED_LEN, drbg->heap,
                            DYNAMIC_TYPE_TMP_BUFFER, ret = MEMORY_E);
            if (ret == 0) {
                thisV = shadowV;
        #if defined(WOLFSSL_ASYNC_CRYPT) || defined(WOLF_CRYPTO_CB)
                ret = wc_InitSha256_ex(sha, drbg->heap, drbg->devId);
        #else
                ret = wc_InitSha256(sha);
        #endif
            }

            if (ret != 0) {
                WC_FREE_VAR_EX(shadowV, drbg->heap, DYNAMIC_TYPE_TMP_BUFFER);
                /* digest holds only the 0 baseline here (never written) */
            #if (!defined(WOLFSSL_SMALL_STACK) || \
                 defined(WOLFSSL_SMALL_STACK_CACHE)) && \
                defined(WOLFSSL_CHECK_MEM_ZERO)
                wc_MemZero_Check(digest, WC_SHA256_DIGEST_SIZE);
            #endif
            #if defined(WOLFSSL_SMALL_STACK) && !defined(WOLFSSL_SMALL_STACK_CACHE)
                XFREE(digest, drbg->heap, DYNAMIC_TYPE_DIGEST);
            #endif
                return DRBG_FAILURE;
            }
#else
            (void)shadowV;
            /* use the upper half of drbg->seed_scratch -- the lower half is
             * used by Hash_gen() for its "data" work buffer. */
            thisV = drbg->seed_scratch + DRBG_SEED_LEN;
            ret = 0;
#endif
            if (ret == 0)
                ret = wc_Sha256Update(sha, &addType, sizeof(addType));
            if (ret == 0)
                ret = wc_Sha256Update(sha, drbg->V, sizeof(drbg->V));
            if (ret == 0)
                ret = wc_Sha256Update(sha, additional, additionalSz);
            if (ret == 0)
                ret = wc_Sha256Final(sha, digest);
#ifdef WOLFSSL_SMALL_STACK_CACHE
            if (ret != 0)
                (void)wc_Sha256Reset(sha);
#else
            wc_Sha256Free(sha);
#endif
            if (ret == 0) {
                XMEMCPY(thisV, drbg->V, DRBG_SEED_LEN);
                array_add(thisV, DRBG_SEED_LEN, digest,
                          WC_SHA256_DIGEST_SIZE);
            }
            else {
                WC_FREE_VAR_EX(shadowV, drbg->heap, DYNAMIC_TYPE_TMP_BUFFER);
                ForceZero(digest, WC_SHA256_DIGEST_SIZE);
            #if (!defined(WOLFSSL_SMALL_STACK) || \
                 defined(WOLFSSL_SMALL_STACK_CACHE)) && \
                defined(WOLFSSL_CHECK_MEM_ZERO)
                wc_MemZero_Check(digest, WC_SHA256_DIGEST_SIZE);
            #endif
            #if defined(WOLFSSL_SMALL_STACK) && !defined(WOLFSSL_SMALL_STACK_CACHE)
                XFREE(digest, drbg->heap, DYNAMIC_TYPE_DIGEST);
            #endif
                return DRBG_FAILURE;
            }
        }
        else {
            thisV = drbg->V;
        }

        ret = Hash_gen(drbg, out, outSz, thisV);
        if (ret == DRBG_SUCCESS) {
#ifndef WOLFSSL_SMALL_STACK_CACHE
        #if defined(WOLFSSL_ASYNC_CRYPT) || defined(WOLF_CRYPTO_CB)
            ret = wc_InitSha256_ex(sha, drbg->heap, drbg->devId);
        #else
            ret = wc_InitSha256(sha);
        #endif
            if (ret == 0)
#endif
                ret = wc_Sha256Update(sha, &type, sizeof(type));
            if (ret == 0)
                ret = wc_Sha256Update(sha, thisV, DRBG_SEED_LEN);
            if (ret == 0)
                ret = wc_Sha256Final(sha, digest);

#ifdef WOLFSSL_SMALL_STACK_CACHE
            if (ret != 0)
                (void)wc_Sha256Reset(sha);
#else
            wc_Sha256Free(sha);
#endif

            if (ret == 0) {
                /* No failure possible from here -- commit thisV if needed. */
                if (thisV != drbg->V)
                    XMEMCPY(drbg->V, thisV, DRBG_SEED_LEN);
                array_add(drbg->V, sizeof(drbg->V), digest, WC_SHA256_DIGEST_SIZE);
                array_add(drbg->V, sizeof(drbg->V), drbg->C, sizeof(drbg->C));
#ifdef WOLFSSL_WIDE_BYTE
                /* A word cannot be aliased as an octet stream where a C byte is
                 * wider than 8 bits; add the counter as big-endian octets. */
            #ifdef WORD64_AVAILABLE
                BytesFromWordsBE64(ctrBuf, &reseedCtr, 8);
                array_add(drbg->V, sizeof(drbg->V), ctrBuf, 8);
            #else
                BytesFromWordsBE32(ctrBuf, &reseedCtr, 4);
                array_add(drbg->V, sizeof(drbg->V), ctrBuf, 4);
            #endif
#else
            #ifdef LITTLE_ENDIAN_ORDER
                #ifdef WORD64_AVAILABLE
                reseedCtr = ByteReverseWord64(reseedCtr);
                #else
                reseedCtr = ByteReverseWord32(reseedCtr);
                #endif
            #endif
                array_add(drbg->V, sizeof(drbg->V),
                                          (byte*)&reseedCtr, sizeof(reseedCtr));
#endif
                ret = DRBG_SUCCESS;
                drbg->reseedCtr++;
            }
            /* else no state mutation, hence no reseed counter increment. */
        }
        ForceZero(digest, WC_SHA256_DIGEST_SIZE);
    #if (!defined(WOLFSSL_SMALL_STACK) || \
         defined(WOLFSSL_SMALL_STACK_CACHE)) && \
        defined(WOLFSSL_CHECK_MEM_ZERO)
        wc_MemZero_Check(digest, WC_SHA256_DIGEST_SIZE);
    #endif
    #if defined(WOLFSSL_SMALL_STACK) && !defined(WOLFSSL_SMALL_STACK_CACHE)
        XFREE(digest, drbg->heap, DYNAMIC_TYPE_DIGEST);
    #endif
    }

    #ifdef WC_VERBOSE_RNG
    if ((ret != DRBG_SUCCESS) && (ret != WC_NO_ERR_TRACE(DRBG_FAILURE))) {
        /* see note above regarding log spam reduction */
        WOLFSSL_DEBUG_PRINTF("ERROR: Hash_DRBG_Generate failed with err %d.",
                             ret);
    }
    #endif

    if ((thisV != drbg->V) && (thisV != NULL))
        ForceZero(thisV, DRBG_SEED_LEN);
    WC_FREE_VAR_EX(shadowV, drbg->heap, DYNAMIC_TYPE_TMP_BUFFER);

    if (ret == 0)
        return DRBG_SUCCESS;
    else {
        /* wipe the stranded output, which would otherwise be repeated
         * on a subsequent successful call.
         */
        ForceZero(out, outSz);
        return DRBG_FAILURE;
    }
}

/* Returns: DRBG_SUCCESS or DRBG_FAILURE */
static WARN_UNUSED_RESULT int Hash_DRBG_Init(DRBG_internal* drbg,
                                             const byte* seed, word32 seedSz,
                                             const byte* nonce, word32 nonceSz,
                                             const byte* perso, word32 persoSz)
{
    if (seed == NULL)
        return DRBG_FAILURE;

    if (Hash_df(drbg, drbg->V, sizeof(drbg->V), drbgInitV, seed, seedSz,
                                              nonce, nonceSz,
                                              perso, persoSz) == DRBG_SUCCESS &&
        Hash_df(drbg, drbg->C, sizeof(drbg->C), drbgInitC, drbg->V,
                                    sizeof(drbg->V), NULL, 0,
                                    NULL, 0) == DRBG_SUCCESS) {

        drbg->reseedCtr = 1;
        return DRBG_SUCCESS;
    }
    else {
        return DRBG_FAILURE;
    }
}

/* Returns: DRBG_SUCCESS or DRBG_FAILURE */
static WARN_UNUSED_RESULT int Hash_DRBG_Instantiate(DRBG_internal* drbg,
                                 const byte* seed, word32 seedSz,
                                 const byte* nonce, word32 nonceSz,
                                 const byte* perso, word32 persoSz,
                                 void* heap, int devId)
{
    int ret = WC_NO_ERR_TRACE(DRBG_FAILURE);

    XMEMSET(drbg, 0, sizeof(DRBG_internal));
#ifdef WC_RNG_HAVE_NEXT_SEED
    wolfSSL_Atomic_Int_Init(&drbg->nextSeedLen, WC_DRBG_NEXT_SEED_EMPTY);
#endif
    drbg->heap = heap;
#if defined(WOLFSSL_ASYNC_CRYPT) || defined(WOLF_CRYPTO_CB)
    drbg->devId = devId;
#else
    (void)devId;
#endif

#ifdef WOLFSSL_SMALL_STACK_CACHE
    #if defined(WOLFSSL_ASYNC_CRYPT) || defined(WOLF_CRYPTO_CB)
        ret = wc_InitSha256_ex(&drbg->sha256, drbg->heap, drbg->devId);
    #else
        ret = wc_InitSha256(&drbg->sha256);
    #endif
    if (ret != 0)
        return ret;
#endif

    if (seed != NULL)
        ret = Hash_DRBG_Init(drbg, seed, seedSz, nonce, nonceSz,
                             perso, persoSz);
    return ret;
}

/* Returns: DRBG_SUCCESS or DRBG_FAILURE */
static int Hash_DRBG_Uninstantiate(DRBG_internal* drbg)
{
    word32 i;
    int    compareSum = 0;
    byte*  compareDrbg = (byte*)drbg;

#ifdef WOLFSSL_SMALL_STACK_CACHE
    wc_Sha256Free(&drbg->sha256);
#endif

    ForceZero(drbg, sizeof(DRBG_internal));

    for (i = 0; i < sizeof(DRBG_internal); i++) {
        compareSum |= compareDrbg[i] ^ 0;
    }

    return (compareSum == 0) ? DRBG_SUCCESS : DRBG_FAILURE;
}

#endif /* !NO_SHA256 - SHA-256 Hash_DRBG core block */

/* ====================================================================== */
/* SHA-512 Hash_DRBG (SP 800-90A Rev 1, Table 2)                          */
/*                                                                        */
/* Internal state (V, C): seedlen = 888 bits = 111 bytes each             */
/* Output block length:   512 bits = 64 bytes (WC_SHA512_DIGEST_SIZE)     */
/* Security strength:     256 bits                                        */
/*                                                                        */
/* NOTE: The raw entropy seed gathered at instantiation / reseed is       */
/* WC_DRBG_SEED_SZ (1024 bits in FIPS builds), NOT seedlen.  We overseed  */
/* to tolerate weak entropy sources.  Hash_df then compresses the seed    */
/* material down to the 888-bit V and derives C from V.  See random.h.    */
/* ====================================================================== */
#ifdef WOLFSSL_DRBG_SHA512

#define OUTPUT_BLOCK_LEN_SHA512  (WC_SHA512_DIGEST_SIZE)  /* 64 bytes */

/* Hash Derivation Function using SHA-512 */
/* Returns: DRBG_SUCCESS or DRBG_FAILURE */
static WARN_UNUSED_RESULT int Hash512_df(DRBG_SHA512_internal* drbg, byte* out,
                                         word32 outSz,
                      byte type,
                      const byte* inA, word32 inASz,
                      const byte* inB, word32 inBSz,
                      const byte* inC, word32 inCSz)
{
    int ret = WC_NO_ERR_TRACE(DRBG_FAILURE);
    byte ctr;
    word32 i;
    word32 len;
    word32 bits = (outSz * 8);
#ifdef WOLFSSL_WIDE_BYTE
    byte bitsBuf[4]; /* the 32-bit length as four big-endian octets */
#endif
#ifdef WOLFSSL_SMALL_STACK_CACHE
    wc_Sha512* sha = &drbg->sha512;
#else
    wc_Sha512 sha[1];
#endif
#if defined(WOLFSSL_SMALL_STACK_CACHE)
    byte* digest = drbg->digest_scratch;
#elif defined(WOLFSSL_SMALL_STACK)
    byte* digest;
#else
#if defined(__GNUC__) && !defined(__clang__) && defined(__AVX512F__)
    /* Use a jumbo alignment to work around a gcc compiler/optimizer bug that
     * assumes AVX512 alignment in an object sized correctly for AVX512 passed
     * to builtin memcpy(), which promptly crashes if not thus aligned.
     */
    byte digest[WC_SHA512_DIGEST_SIZE] WOLFSSL_ALIGN(WC_SHA512_DIGEST_SIZE);
#else
    byte digest[WC_SHA512_DIGEST_SIZE];
#endif
#endif

    if (drbg == NULL) {
        return DRBG_FAILURE;
    }

#if defined(WOLFSSL_SMALL_STACK) && !defined(WOLFSSL_SMALL_STACK_CACHE)
    digest = (byte*)XMALLOC(WC_SHA512_DIGEST_SIZE, drbg->heap,
        DYNAMIC_TYPE_DIGEST);
    if (digest == NULL)
        return DRBG_FAILURE;
#endif

#ifdef WOLFSSL_CHECK_MEM_ZERO
    /* poison so a missed ForceZero on any path is caught by the check */
    XMEMSET(digest, 0xff, WC_SHA512_DIGEST_SIZE);
    wc_MemZero_Add("Hash512_df digest", digest, WC_SHA512_DIGEST_SIZE);
#endif

#ifdef WOLFSSL_WIDE_BYTE
    BytesFromWordsBE32(bitsBuf, &bits, 4);   /* see Hash_df */
#elif defined(LITTLE_ENDIAN_ORDER)
    bits = ByteReverseWord32(bits);
#endif
    len = (outSz / OUTPUT_BLOCK_LEN_SHA512)
        + ((outSz % OUTPUT_BLOCK_LEN_SHA512) ? 1 : 0);

    ctr = 1;
    for (i = 0; i < len; i++) {
#ifndef WOLFSSL_SMALL_STACK_CACHE
    #if defined(WOLFSSL_ASYNC_CRYPT) || defined(WOLF_CRYPTO_CB)
        ret = wc_InitSha512_ex(sha, drbg->heap, drbg->devId);
    #else
        ret = wc_InitSha512(sha);
    #endif
        if (ret != 0)
            break;
#endif
        ret = wc_Sha512Update(sha, &ctr, sizeof(ctr));
        if (ret == 0) {
            ctr++;
#ifdef WOLFSSL_WIDE_BYTE
            ret = wc_Sha512Update(sha, bitsBuf, sizeof(bitsBuf));
#else
            ret = wc_Sha512Update(sha, (byte*)&bits, sizeof(bits));
#endif
        }

        if (ret == 0) {
            /* churning V is the only string that doesn't have the type added */
            if (type != drbgInitV)
                ret = wc_Sha512Update(sha, &type, sizeof(type));
        }
        if (ret == 0)
            ret = wc_Sha512Update(sha, inA, inASz);
        if (ret == 0) {
            if (inB != NULL && inBSz > 0)
                ret = wc_Sha512Update(sha, inB, inBSz);
        }
        if (ret == 0) {
            if (inC != NULL && inCSz > 0)
                ret = wc_Sha512Update(sha, inC, inCSz);
        }
        if (ret == 0)
            ret = wc_Sha512Final(sha, digest);
#ifdef WOLFSSL_SMALL_STACK_CACHE
        if (ret != 0)
            (void)wc_Sha512Reset(sha);
#else
        wc_Sha512Free(sha);
#endif
        if (ret == 0) {
            if (outSz > OUTPUT_BLOCK_LEN_SHA512) {
                XMEMCPY(out, digest, OUTPUT_BLOCK_LEN_SHA512);
                outSz -= OUTPUT_BLOCK_LEN_SHA512;
                out += OUTPUT_BLOCK_LEN_SHA512;
            }
            else {
                XMEMCPY(out, digest, outSz);
            }
        }
        else {
            break;
        }
    }

    ForceZero(digest, WC_SHA512_DIGEST_SIZE);
    /* Explicit check only where the buffer is NOT XFREEd (XFREE auto-checks):
     * the stack build and the small-stack-cache build (drbg member). */
#if (!defined(WOLFSSL_SMALL_STACK) || defined(WOLFSSL_SMALL_STACK_CACHE)) && \
    defined(WOLFSSL_CHECK_MEM_ZERO)
    wc_MemZero_Check(digest, WC_SHA512_DIGEST_SIZE);
#endif

#if defined(WOLFSSL_SMALL_STACK) && !defined(WOLFSSL_SMALL_STACK_CACHE)
    XFREE(digest, drbg->heap, DYNAMIC_TYPE_DIGEST);
#endif

#ifdef WC_VERBOSE_RNG
    if (ret != 0)
        WOLFSSL_DEBUG_PRINTF("ERROR: %s failed with err = %d", __func__,
                             ret);
#endif

    return (ret == 0) ? DRBG_SUCCESS : DRBG_FAILURE;
}

/* Returns: DRBG_SUCCESS or DRBG_FAILURE.  No state mutation on failure. */
static WARN_UNUSED_RESULT int Hash512_DRBG_Reseed(DRBG_SHA512_internal* drbg,
                               const byte* seed, word32 seedSz,
                               const byte* additional, word32 additionalSz)
{
    int ret;
    WC_DECLARE_VAR(newV_C, byte, DRBG_SHA512_SEED_LEN * 2, 0);
    byte *newV, *newC;

    if (drbg == NULL) {
        return DRBG_FAILURE;
    }

#ifdef WOLFSSL_SMALL_STACK_CACHE
    newV_C = drbg->seed_scratch;
#else
    WC_ALLOC_VAR_EX(newV_C, byte, DRBG_SHA512_SEED_LEN * 2, drbg->heap,
        DYNAMIC_TYPE_TMP_BUFFER, return DRBG_FAILURE);
#endif
    XMEMSET(newV_C, 0, DRBG_SHA512_SEED_LEN * 2);
#ifdef WOLFSSL_CHECK_MEM_ZERO
    wc_MemZero_Add("Hash512_DRBG_Reseed newV_C", newV_C,
                   DRBG_SHA512_SEED_LEN * 2);
#endif

    newV = newV_C;
    newC = newV + DRBG_SHA512_SEED_LEN;

    ret = Hash512_df(drbg, newV, DRBG_SHA512_SEED_LEN, drbgReseed,
                drbg->V, sizeof(drbg->V), seed, seedSz,
                additional, additionalSz);
    if (ret == DRBG_SUCCESS) {
        ret = Hash512_df(drbg, newC, DRBG_SHA512_SEED_LEN, drbgInitC, newV,
                                    DRBG_SHA512_SEED_LEN, NULL, 0,
                                    NULL, 0);
    }
    if (ret == DRBG_SUCCESS) {
        XMEMCPY(drbg->V, newV, DRBG_SHA512_SEED_LEN);
        XMEMCPY(drbg->C, newC, DRBG_SHA512_SEED_LEN);
        drbg->reseedCtr = 1;
    }

    ForceZero(newV_C, DRBG_SHA512_SEED_LEN * 2);
#if (!defined(WOLFSSL_SMALL_STACK) || defined(WOLFSSL_SMALL_STACK_CACHE)) && \
    defined(WOLFSSL_CHECK_MEM_ZERO)
    wc_MemZero_Check(newV_C, DRBG_SHA512_SEED_LEN * 2);
#endif

#ifndef WOLFSSL_SMALL_STACK_CACHE
    WC_FREE_VAR_EX(newV_C, drbg->heap, DYNAMIC_TYPE_TMP_BUFFER);
#endif

    return ret;
}

/* Returns: DRBG_SUCCESS or DRBG_FAILURE */
static WARN_UNUSED_RESULT int Hash512_gen(DRBG_SHA512_internal* drbg,
                                          byte* out, word32 outSz,
                                          const byte* V)
{
    int ret = WC_NO_ERR_TRACE(DRBG_FAILURE);
    word32 i;
    word32 len;
#if defined(WOLFSSL_SMALL_STACK_CACHE)
    wc_Sha512* sha = &drbg->sha512;
    byte* data = drbg->seed_scratch; /* Note, top half of seed_scratch is used
                                      * by Hash_DRBG_Generate(). */
    byte* digest = drbg->digest_scratch;
#elif defined(WOLFSSL_SMALL_STACK)
    wc_Sha512 sha[1];
    byte* data = NULL;
    byte* digest = NULL;
#else
    wc_Sha512 sha[1];
    byte data[DRBG_SHA512_SEED_LEN];
    byte digest[WC_SHA512_DIGEST_SIZE];
#endif

    if (drbg == NULL) {
        return DRBG_FAILURE;
    }

#if defined(WOLFSSL_SMALL_STACK) && !defined(WOLFSSL_SMALL_STACK_CACHE)
    data = (byte*)XMALLOC(DRBG_SHA512_SEED_LEN, drbg->heap,
        DYNAMIC_TYPE_TMP_BUFFER);
    digest = (byte*)XMALLOC(WC_SHA512_DIGEST_SIZE, drbg->heap,
        DYNAMIC_TYPE_DIGEST);
    if (data == NULL || digest == NULL) {
        XFREE(digest, drbg->heap, DYNAMIC_TYPE_DIGEST);
        XFREE(data, drbg->heap, DYNAMIC_TYPE_TMP_BUFFER);
        return DRBG_FAILURE;
    }
#endif

    /* Special case: outSz is 0 and out is NULL (Hash_DRBG_StirGenerate()): run
     * a single Hashgen iteration with the block discarded, so the caller gets
     * Generate's V-advance side effects without emitting output.  This
     * preserves standard SP 800-90A sequencing, while presenting call semantics
     * that are convenient for the stir. */
    if (outSz == 0) {
        outSz = 1;
    }

    len = (outSz / OUTPUT_BLOCK_LEN_SHA512)
        + ((outSz % OUTPUT_BLOCK_LEN_SHA512) ? 1 : 0);

    XMEMCPY(data, V, DRBG_SHA512_SEED_LEN);
#ifdef WOLFSSL_CHECK_MEM_ZERO
    wc_MemZero_Add("Hash512_gen data", data, DRBG_SHA512_SEED_LEN);
#endif
    for (i = 0; i < len; i++) {
#ifndef WOLFSSL_SMALL_STACK_CACHE
    #if defined(WOLFSSL_ASYNC_CRYPT) || defined(WOLF_CRYPTO_CB)
        ret = wc_InitSha512_ex(sha, drbg->heap, drbg->devId);
    #else
        ret = wc_InitSha512(sha);
    #endif
        if (ret == 0)
#endif
            ret = wc_Sha512Update(sha, data, DRBG_SHA512_SEED_LEN);
        if (ret == 0)
            ret = wc_Sha512Final(sha, digest);
#ifdef WOLFSSL_SMALL_STACK_CACHE
        if (ret != 0)
            (void)wc_Sha512Reset(sha);
#else
        wc_Sha512Free(sha);
#endif

        if (ret == 0) {
            if (out != NULL && outSz != 0) {
                if (outSz >= OUTPUT_BLOCK_LEN_SHA512) {
                    XMEMCPY(out, digest, OUTPUT_BLOCK_LEN_SHA512);
                    outSz -= OUTPUT_BLOCK_LEN_SHA512;
                    out += OUTPUT_BLOCK_LEN_SHA512;
                    array_add_one(data, DRBG_SHA512_SEED_LEN);
                }
                else {
                    XMEMCPY(out, digest, outSz);
                    outSz = 0;
                }
            }
        }
        else {
            break;
        }
    }
    ForceZero(data, DRBG_SHA512_SEED_LEN);
#if (!defined(WOLFSSL_SMALL_STACK) || defined(WOLFSSL_SMALL_STACK_CACHE)) && \
    defined(WOLFSSL_CHECK_MEM_ZERO)
    wc_MemZero_Check(data, DRBG_SHA512_SEED_LEN);
#endif

#ifndef WOLFSSL_SMALL_STACK_CACHE
    WC_FREE_VAR_EX(digest, drbg->heap, DYNAMIC_TYPE_DIGEST);
    WC_FREE_VAR_EX(data, drbg->heap, DYNAMIC_TYPE_TMP_BUFFER);
#endif

    return (ret == 0) ? DRBG_SUCCESS : DRBG_FAILURE;
}

/* Returns: DRBG_SUCCESS, DRBG_NEED_RESEED, or DRBG_FAILURE.  DRBG state is
 * always consistent upon return, whether success or failure. */
static WARN_UNUSED_RESULT int Hash512_DRBG_Generate(DRBG_SHA512_internal* drbg,
                                 byte* out, word32 outSz,
                                 const byte* additional, word32 additionalSz)
{
    int ret;
#ifdef WOLFSSL_SMALL_STACK_CACHE
    wc_Sha512* sha = &drbg->sha512;
#else
    wc_Sha512 sha[1];
#endif
    byte type;
    word64 reseedCtr;
#ifdef WOLFSSL_WIDE_BYTE
    byte ctrBuf[8]; /* reseed counter as big-endian octets */
#endif
    byte *thisV = NULL;
    WC_DECLARE_VAR(shadowV, byte, DRBG_SHA512_SEED_LEN, 0);

    if (drbg == NULL) {
        return DRBG_FAILURE;
    }

    if (drbg->reseedCtr >= WC_RESEED_INTERVAL) {
        return DRBG_NEED_RESEED;
    }
    else {
    #if defined(WOLFSSL_SMALL_STACK_CACHE)
        byte* digest = drbg->digest_scratch;
    #elif defined(WOLFSSL_SMALL_STACK)
        byte* digest = (byte*)XMALLOC(WC_SHA512_DIGEST_SIZE, drbg->heap,
            DYNAMIC_TYPE_DIGEST);
        if (digest == NULL)
            return DRBG_FAILURE;
    #else
        byte digest[WC_SHA512_DIGEST_SIZE];
    #endif

    #ifdef WOLFSSL_CHECK_MEM_ZERO
        /* baseline 0; registered across the whole generate, force-zeroed and
         * checked at the single exit below (all paths funnel there). */
        XMEMSET(digest, 0, WC_SHA512_DIGEST_SIZE);
        wc_MemZero_Add("Hash512_DRBG_Generate digest", digest,
            WC_SHA512_DIGEST_SIZE);
    #endif

        type = drbgGenerateH;
        reseedCtr = drbg->reseedCtr;

        /* SP 800-90A Section 10.1.1.4 step 2:
         * If additional_input != Null, w = Hash(0x02 || V || additional_input),
         * V = (V + w) mod 2^seedlen */
        ret = DRBG_SUCCESS;
        if (additional != NULL && additionalSz > 0) {
            byte addType = drbgGenerateW; /* 0x02 */
#ifndef WOLFSSL_SMALL_STACK_CACHE
            ret = 0;
            WC_ALLOC_VAR_EX(shadowV, byte, DRBG_SHA512_SEED_LEN, drbg->heap,
                            DYNAMIC_TYPE_TMP_BUFFER, ret = MEMORY_E);
            if (ret == 0) {
                thisV = shadowV;
        #if defined(WOLFSSL_ASYNC_CRYPT) || defined(WOLF_CRYPTO_CB)
                ret = wc_InitSha512_ex(sha, drbg->heap, drbg->devId);
        #else
                ret = wc_InitSha512(sha);
        #endif
            }

            if (ret != 0) {
                WC_FREE_VAR_EX(shadowV, drbg->heap, DYNAMIC_TYPE_TMP_BUFFER);
                /* digest holds only the 0 baseline here (never written) */
            #if (!defined(WOLFSSL_SMALL_STACK) || \
                 defined(WOLFSSL_SMALL_STACK_CACHE)) && \
                defined(WOLFSSL_CHECK_MEM_ZERO)
                wc_MemZero_Check(digest, WC_SHA512_DIGEST_SIZE);
            #endif
            #if defined(WOLFSSL_SMALL_STACK) && !defined(WOLFSSL_SMALL_STACK_CACHE)
                XFREE(digest, drbg->heap, DYNAMIC_TYPE_DIGEST);
            #endif
                return DRBG_FAILURE;
            }
#else
            (void)shadowV;
            /* use the upper half of drbg->seed_scratch -- the lower half is
             * used by Hash512_gen() for its "data" work buffer. */
            thisV = drbg->seed_scratch + DRBG_SHA512_SEED_LEN;
            ret = 0;
#endif
            if (ret == 0)
                ret = wc_Sha512Update(sha, &addType, sizeof(addType));
            if (ret == 0)
                ret = wc_Sha512Update(sha, drbg->V, sizeof(drbg->V));
            if (ret == 0)
                ret = wc_Sha512Update(sha, additional, additionalSz);
            if (ret == 0)
                ret = wc_Sha512Final(sha, digest);
#ifdef WOLFSSL_SMALL_STACK_CACHE
            if (ret != 0)
                (void)wc_Sha512Reset(sha);
#else
            wc_Sha512Free(sha);
#endif
            if (ret == 0) {
                XMEMCPY(thisV, drbg->V, DRBG_SHA512_SEED_LEN);
                array_add(thisV, DRBG_SHA512_SEED_LEN, digest,
                          WC_SHA512_DIGEST_SIZE);
            }
            else {
                WC_FREE_VAR_EX(shadowV, drbg->heap, DYNAMIC_TYPE_TMP_BUFFER);
                ForceZero(digest, WC_SHA512_DIGEST_SIZE);
            #if (!defined(WOLFSSL_SMALL_STACK) || \
                 defined(WOLFSSL_SMALL_STACK_CACHE)) && \
                defined(WOLFSSL_CHECK_MEM_ZERO)
                wc_MemZero_Check(digest, WC_SHA512_DIGEST_SIZE);
            #endif
            #if defined(WOLFSSL_SMALL_STACK) && !defined(WOLFSSL_SMALL_STACK_CACHE)
                XFREE(digest, drbg->heap, DYNAMIC_TYPE_DIGEST);
            #endif
                return DRBG_FAILURE;
            }
        }
        else {
            thisV = drbg->V;
        }

        if (ret == 0)
            ret = Hash512_gen(drbg, out, outSz, thisV);
        if (ret == DRBG_SUCCESS) {
#ifndef WOLFSSL_SMALL_STACK_CACHE
        #if defined(WOLFSSL_ASYNC_CRYPT) || defined(WOLF_CRYPTO_CB)
            ret = wc_InitSha512_ex(sha, drbg->heap, drbg->devId);
        #else
            ret = wc_InitSha512(sha);
        #endif
            if (ret == 0)
#endif
                ret = wc_Sha512Update(sha, &type, sizeof(type));
            if (ret == 0)
                ret = wc_Sha512Update(sha, thisV, DRBG_SHA512_SEED_LEN);
            if (ret == 0)
                ret = wc_Sha512Final(sha, digest);
#ifdef WOLFSSL_SMALL_STACK_CACHE
            if (ret != 0)
                (void)wc_Sha512Reset(sha);
#else
            wc_Sha512Free(sha);
#endif

            if (ret == 0) {
                /* No failure possible from here -- commit thisV if needed. */
                if (thisV != drbg->V)
                    XMEMCPY(drbg->V, thisV, DRBG_SHA512_SEED_LEN);
                array_add(drbg->V, sizeof(drbg->V), digest,
                          WC_SHA512_DIGEST_SIZE);
                array_add(drbg->V, sizeof(drbg->V), drbg->C, sizeof(drbg->C));
#ifdef WOLFSSL_WIDE_BYTE
                /* See Hash_DRBG_Generate. */
                BytesFromWordsBE64(ctrBuf, &reseedCtr, 8);
                array_add(drbg->V, sizeof(drbg->V), ctrBuf, 8);
#else
            #ifdef LITTLE_ENDIAN_ORDER
                reseedCtr = ByteReverseWord64(reseedCtr);
            #endif
                array_add(drbg->V, sizeof(drbg->V),
                                          (byte*)&reseedCtr, sizeof(reseedCtr));
#endif
                ret = DRBG_SUCCESS;
                drbg->reseedCtr++;
            }
            /* else no state mutation, hence no reseed counter increment. */
        }
        ForceZero(digest, WC_SHA512_DIGEST_SIZE);
    #if (!defined(WOLFSSL_SMALL_STACK) || \
         defined(WOLFSSL_SMALL_STACK_CACHE)) && \
        defined(WOLFSSL_CHECK_MEM_ZERO)
        wc_MemZero_Check(digest, WC_SHA512_DIGEST_SIZE);
    #endif
    #if defined(WOLFSSL_SMALL_STACK) && !defined(WOLFSSL_SMALL_STACK_CACHE)
        XFREE(digest, drbg->heap, DYNAMIC_TYPE_DIGEST);
    #endif
    }

    if ((thisV != drbg->V) && (thisV != NULL))
        ForceZero(thisV, DRBG_SHA512_SEED_LEN);
    WC_FREE_VAR_EX(shadowV, drbg->heap, DYNAMIC_TYPE_TMP_BUFFER);

    if (ret == 0)
        return DRBG_SUCCESS;
    else {
        /* wipe the stranded output, which would otherwise be repeated
         * on a subsequent successful call.
         */
        ForceZero(out, outSz);
        return DRBG_FAILURE;
    }
}

/* Returns: DRBG_SUCCESS or DRBG_FAILURE */
static WARN_UNUSED_RESULT int Hash512_DRBG_Init(DRBG_SHA512_internal* drbg,
                             const byte* seed, word32 seedSz,
                             const byte* nonce, word32 nonceSz,
                             const byte* perso, word32 persoSz)
{
    if (seed == NULL)
        return DRBG_FAILURE;

    if (Hash512_df(drbg, drbg->V, sizeof(drbg->V), drbgInitV, seed, seedSz,
                                              nonce, nonceSz,
                                              perso, persoSz) == DRBG_SUCCESS &&
        Hash512_df(drbg, drbg->C, sizeof(drbg->C), drbgInitC, drbg->V,
                                    sizeof(drbg->V), NULL, 0,
                                    NULL, 0) == DRBG_SUCCESS) {

        drbg->reseedCtr = 1;
        return DRBG_SUCCESS;
    }
    else {
        return DRBG_FAILURE;
    }
}

/* Returns: DRBG_SUCCESS or DRBG_FAILURE */
static WARN_UNUSED_RESULT int Hash512_DRBG_Instantiate(
                                    DRBG_SHA512_internal* drbg,
                                    const byte* seed, word32 seedSz,
                                    const byte* nonce, word32 nonceSz,
                                    const byte* perso, word32 persoSz,
                                    void* heap, int devId)
{
    int ret = WC_NO_ERR_TRACE(DRBG_FAILURE);

    XMEMSET(drbg, 0, sizeof(DRBG_SHA512_internal));
#ifdef WC_RNG_HAVE_NEXT_SEED
    wolfSSL_Atomic_Int_Init(&drbg->nextSeedLen, WC_DRBG_NEXT_SEED_EMPTY);
#endif
    drbg->heap = heap;
#if defined(WOLFSSL_ASYNC_CRYPT) || defined(WOLF_CRYPTO_CB)
    drbg->devId = devId;
#else
    (void)devId;
#endif

#ifdef WOLFSSL_SMALL_STACK_CACHE
    #if defined(WOLFSSL_ASYNC_CRYPT) || defined(WOLF_CRYPTO_CB)
        ret = wc_InitSha512_ex(&drbg->sha512, drbg->heap, drbg->devId);
    #else
        ret = wc_InitSha512(&drbg->sha512);
    #endif
    if (ret != 0)
        return ret;
#endif

    if (seed != NULL)
        ret = Hash512_DRBG_Init(drbg, seed, seedSz, nonce, nonceSz,
                                perso, persoSz);
    return ret;
}

/* Returns: DRBG_SUCCESS or DRBG_FAILURE */
static int Hash512_DRBG_Uninstantiate(DRBG_SHA512_internal* drbg)
{
    word32 i;
    int    compareSum = 0;
    byte*  compareDrbg = (byte*)drbg;

#ifdef WOLFSSL_SMALL_STACK_CACHE
    wc_Sha512Free(&drbg->sha512);
#endif

    ForceZero(drbg, sizeof(DRBG_SHA512_internal));

    for (i = 0; i < sizeof(DRBG_SHA512_internal); i++) {
        compareSum |= compareDrbg[i] ^ 0;
    }

    return (compareSum == 0) ? DRBG_SUCCESS : DRBG_FAILURE;
}

#endif /* WOLFSSL_DRBG_SHA512 */

/* Uncredited stirring, per SP 800-90A 10.1.1.4 generate with additional_input
 * (step 2: V += Hash(0x02 || V || additional_input)).  The generate is
 * zero-length: Hash_gen()'s (and Hash512_gen()'s) outSz==0 mode banks the
 * generated block for the continuous-test hook (its consumer is
 * configuration-dependent; no comparison state lives in this file), and
 * out is never dereferenced.  The reseed counter is incremented as for any
 * generate, and quarantine/stratum are untouched, so the no-claims doctrine
 * holds as a theorem of the standard rather than a property of a custom
 * transition.  Refused with NOT_READY_E when the instance is quarantined or due
 * for a credited reseed: a generate must not run past the reseed interval. */

static WARN_UNUSED_RESULT int Hash_DRBG_StirGenerate(WC_RNG* rng,
                                                     const byte* add,
                                                     word32 addSz)
{
    wc_drbg_reseed_ctr_t ctr = 0;
    int ret;

#ifdef WC_RNG_HAVE_LOCK
    /* The lock word is the atomic source of truth for quarantine: the
     * invalidator's counter saturation can be lost to a racing
     * lease-holder's plain reseedCtr++, but the latch cannot.  Checked
     * before the counter for exactly that reason. */
    if (WOLFSSL_ATOMIC_LOAD(rng->lock) & WC_RNG_LOCK_ENTROPY_INVALIDATED)
        return NOT_READY_E;
#endif
    ret = wc_RNG_DRBG_GetReseedCtr(rng, &ctr);
    if (ret != 0)
        return ret;
    if (ctr >= WC_RESEED_INTERVAL)
        return NOT_READY_E;

    ret = RNG_FAILURE_E;
#ifndef NO_SHA256
    if ((rng->drbgType == WC_DRBG_SHA256) && (rng->drbg != NULL)) {
        ret = Hash_DRBG_Generate((DRBG_internal *)rng->drbg, NULL, 0,
                                 add, addSz);
    }
#endif
#ifdef WOLFSSL_DRBG_SHA512
    if ((rng->drbgType == WC_DRBG_SHA512) && (rng->drbg512 != NULL)) {
        ret = Hash512_DRBG_Generate((DRBG_SHA512_internal *)rng->drbg512,
                                    NULL, 0, add, addSz);
    }
#endif
#ifdef WC_RNG_DEBUG_STATS
    if (ret == 0)
        ++rng->_stats_stirs; /* counts uncredited stir-generates. */
#endif

    if (ret == DRBG_NEED_RESEED)
        return NOT_READY_E;
    else if (ret > 0)
        return RNG_FAILURE_E;
    else
        return ret;
}

static WARN_UNUSED_RESULT int wc_RNG_DRBG_Stir_Nonce_local(WC_RNG* rng,
                                        const byte* seed, word32 seedSz,
                                        const byte *nonce, word32 nonceSz)
{
    if (rng == NULL || seed == NULL)
        return BAD_FUNC_ARG;
    if ((nonce == NULL) && (nonceSz != 0))
        return BAD_FUNC_ARG;

    if (rng->status != WC_DRBG_OK)
        return RNG_FAILURE_E;

    {
        int lock_ret = rng_lock_required_check(rng);
        if (lock_ret != 0)
            return lock_ret;
    }

    {
        int ret = Hash_DRBG_StirGenerate(rng, seed, seedSz);
        if ((ret == 0) && (nonce != NULL) && (nonceSz > 0)) {
            /* Second chunk as its own specified generate: additional
             * input is per-call, and chunking beats concatenation
             * scratch. */
            ret = Hash_DRBG_StirGenerate(rng, nonce, nonceSz);
        }
        return ret;
    }
}

int wc_RNG_DRBG_Stir_Nonce(WC_RNG* rng, const byte* seed, word32 seedSz,
                           const byte *nonce, word32 nonceSz)
{
    int ret;

    if (rng == NULL)
        return BAD_FUNC_ARG;
    ret = RngAutoLockEnter(rng);
    if (ret != 0)
        return ret;
    ret = wc_RNG_DRBG_Stir_Nonce_local(rng, seed, seedSz, nonce, nonceSz);
    RngAutoLockExit(rng);
    return ret;
}

int wc_RNG_DRBG_Stir(WC_RNG* rng, const byte* seed, word32 seedSz)
{
    return wc_RNG_DRBG_Stir_Nonce(rng, seed, seedSz, NULL, 0);
}

/* FIPS 140-3 IG 10.3.A / SP800-90B Health Tests for Seed Data
 *
 * These tests replace the older FIPS 140-2 Continuous Random Number Generator
 * Test (CRNGT) with more mathematically robust statistical tests per
 * ISO 19790 / SP800-90B requirements.
 *
 * When HAVE_ENTROPY_MEMUSE is defined, the wolfentropy.c jitter-based TRNG
 * performs another set of these health tests, but those are on the noise not
 * the conditioned output so we still need to retest here even in that case
 * to evaluate the conditioned output for the same behavior. These tests ensure
 * the seed data meets basic entropy requirements regardless of the source.
 */

/* SP800-90B 4.4.1 - Repetition Count Test
 * Detects if the noise source becomes "stuck" producing repeated output.
 *
 * C = 1 + ceil(-log2(alpha) / H)
 * For alpha = 2^-30 (false positive probability) and H = 1 (min entropy):
 * C = 1 + ceil(30 / 1) = 31
 */
#ifndef WC_RNG_SEED_RCT_CUTOFF
    #define WC_RNG_SEED_RCT_CUTOFF 31
#endif

/* SP800-90B 4.4.2 - Adaptive Proportion Test
 * Monitors if a particular sample value appears too frequently within a
 * window of samples, indicating loss of entropy.
 *
 * Window size W = 512 for non-binary alphabet (byte values 0-255)
 * C = 1 + CRITBINOM(W, 2^(-H), 1-alpha)
 * For alpha = 2^-30 and H = 1, W = 512:
 * C = 1 + CRITBINOM(512, 0.5, 1-2^-30) = 325
 */
#ifndef WC_RNG_SEED_APT_WINDOW
    #define WC_RNG_SEED_APT_WINDOW 512
#endif
#ifndef WC_RNG_SEED_APT_CUTOFF
    #define WC_RNG_SEED_APT_CUTOFF 325
#endif

int wc_RNG_TestSeed(const byte* seed, word32 seedSz)
{
    int ret = 0;

    word32 i;
    int rctFailed = 0;
    int aptFailed = 0;

    if (seed == NULL || seedSz < SEED_BLOCK_SZ) {
        return BAD_FUNC_ARG;
    }

    /* SP800-90B 4.4.1 - Repetition Count Test (RCT)
     * Check for consecutive identical bytes that would indicate a stuck
     * entropy source. Fail if we see WC_RNG_SEED_RCT_CUTOFF or more
     * consecutive identical values.
     *
     * Constant-time implementation: always process full seed, accumulate
     * failure status without early exit to prevent timing side-channels.
     */
    {
        int repCount = 1;
        byte prevByte = seed[0];

        for (i = 1; i < seedSz; i++) {
            /* Constant-time: always evaluate both branches effects */
            int match = (seed[i] == prevByte);
            /* If match, increment count, if not, reset to 1 */
            repCount = (match * (repCount + 1)) + (!match * 1);
            /* Update prevByte only when not matching (new value) */
            prevByte = (byte) ((match * prevByte) + (!match * seed[i]));
            /* Accumulate failure flag - once set, stays set */
            rctFailed |= (repCount >= WC_RNG_SEED_RCT_CUTOFF);
        }
    }

    /* SP800-90B 4.4.2 - Adaptive Proportion Test (APT)
     * Check that no single byte value appears too frequently within
     * a sliding window. This detects bias in the entropy source.
     *
     * For seeds smaller than the window size, we test the entire seed.
     * For larger seeds, we use a sliding window approach.
     *
     * Constant-time implementation: always process full seed and check
     * all counts to prevent timing side-channels.
     */
    {
    #if defined(WOLFSSL_SMALL_STACK) && !defined(WOLFSSL_SMALL_STACK_CACHE)
        word16* byteCounts = NULL;
    #else
        word16 byteCounts[MAX_ENTROPY_BITS];
    #endif
        word32 windowSize = min(seedSz, (word32)WC_RNG_SEED_APT_WINDOW);
        word32 windowStart = 0;
        word32 newIdx;

    #if defined(WOLFSSL_SMALL_STACK) && !defined(WOLFSSL_SMALL_STACK_CACHE)
        byteCounts = (word16*)XMALLOC(MAX_ENTROPY_BITS * sizeof(word16), NULL,
                                      DYNAMIC_TYPE_TMP_BUFFER);
        if (byteCounts == NULL)
            return MEMORY_E;
    #endif
        XMEMSET(byteCounts, 0, MAX_ENTROPY_BITS * sizeof(word16));

        /* Indices are WC_OCTET-masked: byteCounts has 256 entries, but a
         * byte cell can exceed 255 where CHAR_BIT != 8, so an unmasked seed
         * value would index out of bounds. */
        for (i = 0; i < windowSize; i++) {
            byteCounts[WC_OCTET(seed[i])]++;
        }

        /* Check first window - scan all 256 counts */
        for (i = 0; i < MAX_ENTROPY_BITS; i++) {
            aptFailed |= (byteCounts[i] >= WC_RNG_SEED_APT_CUTOFF);
        }

        /* Slide window through remaining seed data */
        while ((windowStart + windowSize) < seedSz) {
            /* Remove byte leaving the window */
            byteCounts[WC_OCTET(seed[windowStart])]--;
            windowStart++;

            /* Add byte entering the window */
            newIdx = windowStart + windowSize - 1;
            byteCounts[WC_OCTET(seed[newIdx])]++;

            /* Accumulate failure flag for new byte's count */
            aptFailed |= (byteCounts[WC_OCTET(seed[newIdx])] >=
                          WC_RNG_SEED_APT_CUTOFF);
        }

    #if defined(WOLFSSL_SMALL_STACK) && !defined(WOLFSSL_SMALL_STACK_CACHE)
        XFREE(byteCounts, NULL, DYNAMIC_TYPE_TMP_BUFFER);
    #endif
    }

    /* Set return code based on accumulated failure flags */
    if (rctFailed) {
        ret = ENTROPY_RT_E;
    }
    else if (aptFailed) {
        ret = ENTROPY_APT_E;
    }

    return ret;
}
/* Runtime DRBG disable/enable API -- only available in non-selftest and
 * FIPS v7+ builds (older FIPS/selftest random.c doesn't have these) */
#if !defined(HAVE_SELFTEST) && \
    (!defined(HAVE_FIPS) || FIPS_VERSION3_GE(7,0,0))
#ifndef NO_SHA256
int wc_Sha256Drbg_Disable(void)
{
    int ret;
#ifdef WOLFSSL_DRBG_SHA512
    ret = LockDrbgState();
    if (ret != 0)
        return ret;
    if (sha512DrbgDisabled) {
        UnlockDrbgState();
        return BAD_STATE_E;  /* can't disable both */
    }
    sha256DrbgDisabled = 1;
    UnlockDrbgState();
    return 0;
#else
    (void)ret;
    return NOT_COMPILED_IN;
#endif
}

int wc_Sha256Drbg_Enable(void)
{
    int ret = LockDrbgState();
    if (ret != 0)
        return ret;
    sha256DrbgDisabled = 0;
    UnlockDrbgState();
    return 0;
}

int wc_Sha256Drbg_IsDisabled(void)
{
    int val;
    if (LockDrbgState() != 0)
        return 1; /* fail-safe: report disabled on mutex error */
    val = sha256DrbgDisabled;
    UnlockDrbgState();
    return val;
}
#else
/* When SHA-256 is not compiled in, these are stubs */
int wc_Sha256Drbg_Disable(void) { return NOT_COMPILED_IN; }
int wc_Sha256Drbg_Enable(void) { return 0; }
int wc_Sha256Drbg_IsDisabled(void) { return 1; } /* always disabled */
#endif /* !NO_SHA256 */

#ifdef WOLFSSL_DRBG_SHA512
int wc_Sha512Drbg_Disable(void)
{
    int ret = LockDrbgState();
    if (ret != 0)
        return ret;
#ifndef NO_SHA256
    if (sha256DrbgDisabled) {
        UnlockDrbgState();
        return BAD_STATE_E;  /* can't disable both */
    }
#endif
    sha512DrbgDisabled = 1;
    UnlockDrbgState();
    return 0;
}

int wc_Sha512Drbg_Enable(void)
{
    int ret = LockDrbgState();
    if (ret != 0)
        return ret;
    sha512DrbgDisabled = 0;
    UnlockDrbgState();
    return 0;
}

int wc_Sha512Drbg_IsDisabled(void)
{
    int val;
    if (LockDrbgState() != 0)
        return 1; /* fail-safe: report disabled on mutex error */
    val = sha512DrbgDisabled;
    UnlockDrbgState();
    return val;
}
#endif /* WOLFSSL_DRBG_SHA512 */
#endif /* !HAVE_SELFTEST && (!HAVE_FIPS || FIPS v7+) */
#else
    /* no Hash DRBG, so no lock for the backends to hold */
    #define RngAutoLockEnter(rng) 0
    #define RngAutoLockExit(rng)  WC_DO_NOTHING
#endif /* HAVE_HASHDRBG */
/* End NIST DRBG Code */

/* Semantics of "flags":
 *
 * Security attributes are fixed at instantiation and caller-declared -- the
 * constructor never reads the target object.  _LOCK_REQUIRED sets the sticky
 * WC_RNG_LOCK_REQUIRED latch bit at birth, so there is no reachable state in
 * which the instance serves without its lock policy.  _LOCK_INITIALLY sets
 * WC_RNG_LOCK_HELD at birth: the caller is the lease holder from the first
 * instruction -- the flag for constructing into a held lease (a lease-holding
 * reinitialization keeps the instance invariantly locked across the reinit), to
 * be released by wc_RNG_lock_put() as usual.  _USE_FULL_MUTEX layers a blocking
 * wolfSSL_Mutex outermost around wc_RNG_lock_get() and wc_RNG_lock_put*() --
 * for user-mode sharing of one instance among threads, where spinning on the
 * CAS would be wrong; contending getters sleep in wc_LockMutex().  The inner
 * latch (and every other wc_RNG_lock_*() operation) is unchanged.
 * NOT_COMPILED_IN unless WC_RNG_HAVE_LOCK_FULL_MUTEX; composes with
 * _LOCK_INITIALLY (born held at both layers).  wc_FreeRng() releases (if the
 * latch is held) and frees the mutex.
 */
static WARN_UNUSED_RESULT int _InitRng(WC_RNG* rng,
                    const byte* nonce, word32 nonceSz,
                    const byte *perso, word32 persoSz,
                    void* heap, int devId, WC_RNG* seedRng, word32 flags)
{
    int ret = 0;
#if defined(HAVE_HASHDRBG) && !defined(CUSTOM_RAND_GENERATE_BLOCK)
#if !defined(HAVE_FIPS) && defined(WOLFSSL_RNG_USE_FULL_SEED)
    word32 seedSz = SEED_SZ;
#else
    word32 seedSz = SEED_SZ + SEED_BLOCK_SZ;
#endif
    WC_DECLARE_VAR(seed, byte, MAX_SEED_SZ, rng->heap);
    int drbg_instantiated = 0;
#ifdef WOLFSSL_SMALL_STACK_CACHE
    int drbg_scratch_instantiated = 0;
#endif
#endif

    (void)nonce;
    (void)nonceSz;
    (void)perso;
    (void)persoSz;
    /* seedRng is consumed only in the seed-acquisition arm; cast for
     * configurations that compile that arm out. */
    (void)seedRng;

    if (rng == NULL)
        return BAD_FUNC_ARG;
    if (nonce == NULL && nonceSz != 0)
        return BAD_FUNC_ARG;
    if (perso == NULL && persoSz != 0)
        return BAD_FUNC_ARG;

    /* Checked before the build tests below, so a contradictory request is
     * refused the same way everywhere rather than depending on the build. */
    if ((flags & WC_RNG_INIT_FLAG_USE_AUTO_LOCK) &&
        (flags & (WC_RNG_INIT_FLAG_NO_AUTO_LOCK |
                  WC_RNG_INIT_FLAG_USE_FULL_MUTEX)))
    {
        return BAD_FUNC_ARG;
    }
#ifndef WC_RNG_HAVE_NEXT_SEED
    if (flags & WC_RNG_INIT_FLAG_RECOVER_AND_PROMOTE_FROM_NEXT_SEED)
        return NOT_COMPILED_IN;
#endif
#ifndef WC_RNG_HAVE_LOCK_FULL_MUTEX
    if (flags & WC_RNG_INIT_FLAG_USE_FULL_MUTEX)
        return NOT_COMPILED_IN;
#endif
#ifndef WC_RNG_HAVE_AUTO_LOCK
    /* Refuse rather than return an instance the caller believes is locked.
     * Turning it off where there is none to turn off stays a no-op. */
    if (flags & WC_RNG_INIT_FLAG_USE_AUTO_LOCK)
        return NOT_COMPILED_IN;
#endif

#ifdef WC_RNG_HAVE_LOCK
    if (flags & (WC_RNG_INIT_FLAG_LOCK_REQUIRED |
                 WC_RNG_INIT_FLAG_LOCK_INITIALLY))
    {
        word32 initial_flags =
            ((flags & WC_RNG_INIT_FLAG_LOCK_REQUIRED) ?
             WC_RNG_LOCK_REQUIRED : 0) |
            ((flags & WC_RNG_INIT_FLAG_LOCK_INITIALLY) ?
             WC_RNG_LOCK_HELD : 0);
        XMEMSET(rng, 0, WC_OFFSETOF(WC_RNG, lock));
        XMEMSET((byte *)rng + WC_OFFSETOF(WC_RNG, lock) + sizeof(rng->lock), 0,
                sizeof(*rng) -
                (WC_OFFSETOF(WC_RNG, lock) + sizeof(rng->lock)));
        #ifdef WC_RNG_DEBUG_STATS
        if (flags & WC_RNG_INIT_FLAG_LOCK_INITIALLY)
            rng->_stats_locks_taken = 1;
        #endif
#ifdef WOLFSSL_NO_ATOMICS
        rng->lock = initial_flags;
#else
        wolfSSL_Atomic_Uint_Init(&rng->lock, initial_flags);
#endif
    }
    else
#endif /* WC_RNG_HAVE_LOCK */
    {
        XMEMSET(rng, 0, sizeof(*rng));
    }

#ifdef WC_RNG_HAVE_RBGC
    if (seedRng == NULL)
        rng->RBGCStratum = 0;
    else {
        if (seedRng->RBGCStratum >= WC_MAX_SINT_OF(int))
            return SEQ_OVERFLOW_E;
        else if (seedRng->RBGCStratum == WC_RNG_RBGC_USER_SEED_STRATUM - 1)
            return SEQ_OVERFLOW_E;
        rng->RBGCStratum = seedRng->RBGCStratum + 1;
    }
#endif

#ifdef WOLFSSL_HEAP_TEST
    rng->heap = (void*)WOLFSSL_HEAP_TEST;
    (void)heap;
#else
    rng->heap = heap;
#endif
#if defined(HAVE_GETPID) && !defined(WOLFSSL_NO_GETPID)
    rng->pid = getpid();
#endif
#if defined(WOLFSSL_ASYNC_CRYPT) || defined(WOLF_CRYPTO_CB)
    rng->devId = devId;
    #if defined(WOLF_CRYPTO_CB)
        rng->seed.devId = devId;
    #endif
#else
    (void)devId;
#endif

#ifdef HAVE_HASHDRBG
    /* init the DBRG to known values */
#ifndef NO_SHA256
    rng->drbg = NULL;
    #ifdef WOLFSSL_SMALL_STACK_CACHE
    rng->drbg_scratch = NULL;
    #endif
#endif /* !NO_SHA256 */
#ifdef WOLFSSL_DRBG_SHA512
    rng->drbg512 = NULL;
    #ifdef WOLFSSL_SMALL_STACK_CACHE
    rng->drbg512_scratch = NULL;
    rng->health_check_scratch_512 = NULL;
    #endif
#endif /* WOLFSSL_DRBG_SHA512 */
#ifdef WOLFSSL_SMALL_STACK_CACHE
    rng->newSeed_buf = NULL;
    #ifndef NO_SHA256
    rng->health_check_scratch = NULL;
    #endif /* !NO_SHA256 */
#endif /* WOLFSSL_SMALL_STACK_CACHE */
    rng->status = DRBG_NOT_INIT;

    /* Select DRBG type: prefer SHA-512 unless disabled or not compiled.
     * Hold the mutex for a consistent snapshot of both disable flags. */
#if !defined(HAVE_SELFTEST) && (!defined(HAVE_FIPS) || FIPS_VERSION3_GE(7,0,0))
    ret = LockDrbgState();
    if (ret != 0)
        return ret;
    #ifdef WOLFSSL_DRBG_SHA512
    if (!sha512DrbgDisabled)
        rng->drbgType = WC_DRBG_SHA512;
    else
    #endif /* WOLFSSL_DRBG_SHA512 */
    #ifndef NO_SHA256
    if (!sha256DrbgDisabled)
        rng->drbgType = WC_DRBG_SHA256;
    else
    #endif /* !NO_SHA256 */
    {
        UnlockDrbgState();
        return BAD_STATE_E; /* no DRBG available */
    }
    UnlockDrbgState();
#else
    rng->drbgType = WC_DRBG_SHA256;
#endif /* !HAVE_SELFTEST && (!HAVE_FIPS || FIPS v7+) */
#endif /* HAVE_HASHDRBG */

#if defined(HAVE_INTEL_RDSEED) || defined(HAVE_INTEL_RDRAND) || \
    defined(HAVE_AMD_RDSEED)
    /* init the intel RD seed and/or rand */
    wc_InitRng_IntelRD();
#endif

    /* configure async RNG source if available */
#ifdef WOLFSSL_ASYNC_CRYPT
    ret = wolfAsync_DevCtxInit(&rng->asyncDev, WOLFSSL_ASYNC_MARKER_RNG,
                                                        rng->heap, rng->devId);
    if (ret != 0) {
    #ifdef HAVE_HASHDRBG
        rng->status = DRBG_OK;
    #endif
        return ret;
    }
#endif

#ifdef HAVE_INTEL_RDRAND
    /* if CPU supports RDRAND, use it directly and bypass DRBG init */
    if (IS_INTEL_RDRAND(intel_flags)) {
    #ifdef HAVE_HASHDRBG
        rng->status = DRBG_OK;
    #endif
#ifdef WC_RNG_HAVE_RBGC
        /* undo stratum increment */
        if (seedRng != NULL)
            rng->RBGCStratum = 0;
#endif
        return 0;
    }
#endif

#ifdef WOLFSSL_XILINX_CRYPT_VERSAL
    ret = wc_VersalTrngInit(nonce, nonceSz);
    if (ret) {
    #ifdef HAVE_HASHDRBG
        rng->status = DRBG_OK;
    #endif
        return ret;
    }
#endif

#if defined(WOLFSSL_KEEP_RNG_SEED_FD_OPEN) && !defined(USE_WINDOWS_API)
    if (!rng->seed.seedFdOpen)
        rng->seed.fd = XBADFD;
#endif

#ifdef CUSTOM_RAND_GENERATE_BLOCK
    ret = 0; /* success */
#else

#ifdef WC_RNG_HAVE_NEXT_SEED
    wolfSSL_Atomic_Int_Init(&rng->nextStirLen,
                            WC_DRBG_NEXT_SEED_EMPTY);
#endif

 /* not CUSTOM_RAND_GENERATE_BLOCK follows */
#ifdef HAVE_HASHDRBG
    if (nonceSz == 0) {
        seedSz = MAX_SEED_SZ;
    }

#ifndef NO_SHA256
    if (rng->drbgType == WC_DRBG_SHA256) {
    #if !defined(WOLFSSL_NO_MALLOC) || defined(WOLFSSL_STATIC_MEMORY)
        rng->drbg =
            (struct DRBG*)XMALLOC(sizeof(DRBG_internal), rng->heap,
                                  DYNAMIC_TYPE_RNG);
        if (rng->drbg == NULL) {
        #if defined(DEBUG_WOLFSSL)
            WOLFSSL_MSG_EX("_InitRng XMALLOC failed to allocate %d bytes",
                           sizeof(DRBG_internal));
        #endif
            ret = MEMORY_E;
            rng->status = DRBG_FAILED;
        }
    #else
        rng->drbg = (struct DRBG*)&rng->drbg_data;
    #endif /* WOLFSSL_NO_MALLOC or WOLFSSL_STATIC_MEMORY */

    #ifdef WOLFSSL_SMALL_STACK_CACHE
        if (ret == 0) {
            rng->drbg_scratch =
                (DRBG_internal *)XMALLOC(sizeof(DRBG_internal), rng->heap,
                                         DYNAMIC_TYPE_RNG);
            if (rng->drbg_scratch == NULL) {
    #if defined(DEBUG_WOLFSSL)
                WOLFSSL_MSG_EX("_InitRng XMALLOC failed to allocate %d bytes",
                               sizeof(DRBG_internal));
    #endif
                ret = MEMORY_E;
                rng->status = DRBG_FAILED;
            }
        }

        if (ret == 0) {
            ret = Hash_DRBG_Instantiate((DRBG_internal *)rng->drbg_scratch,
                        NULL, 0, NULL, 0, NULL, 0, rng->heap, devId);
            if (ret == 0)
                drbg_scratch_instantiated = 1;
        }

        if (ret == 0) {
            rng->health_check_scratch =
                (byte *)XMALLOC(RNG_HEALTH_TEST_CHECK_SIZE, rng->heap,
                                DYNAMIC_TYPE_TMP_BUFFER);
            if (rng->health_check_scratch == NULL) {
                ret = MEMORY_E;
                rng->status = DRBG_FAILED;
            }
        }
    #endif /* WOLFSSL_SMALL_STACK_CACHE */
    } /* WC_DRBG_SHA256 */
#endif /* !NO_SHA256 */

#ifdef WOLFSSL_DRBG_SHA512
    if (rng->drbgType == WC_DRBG_SHA512) {
    #if !defined(WOLFSSL_NO_MALLOC) || defined(WOLFSSL_STATIC_MEMORY)
        rng->drbg512 =
            (struct DRBG_SHA512*)XMALLOC(sizeof(DRBG_SHA512_internal),
                                         rng->heap, DYNAMIC_TYPE_RNG);
        if (rng->drbg512 == NULL) {
        #if defined(DEBUG_WOLFSSL)
            WOLFSSL_MSG_EX("_InitRng XMALLOC failed to allocate %d bytes",
                           sizeof(DRBG_SHA512_internal));
        #endif
            ret = MEMORY_E;
            rng->status = DRBG_FAILED;
        }
    #else
        rng->drbg512 = (struct DRBG_SHA512*)&rng->drbg512_data;
    #endif

    #ifdef WOLFSSL_SMALL_STACK_CACHE
        if (ret == 0) {
            rng->drbg512_scratch =
                (DRBG_SHA512_internal *)XMALLOC(sizeof(DRBG_SHA512_internal),
                    rng->heap, DYNAMIC_TYPE_RNG);
            if (rng->drbg512_scratch == NULL) {
                ret = MEMORY_E;
                rng->status = DRBG_FAILED;
            }
        }

        if (ret == 0) {
            ret = Hash512_DRBG_Instantiate(rng->drbg512_scratch,
                        NULL, 0, NULL, 0, NULL, 0, rng->heap, devId);
            if (ret == 0)
                drbg_scratch_instantiated = 1;
        }

        if (ret == 0) {
            rng->health_check_scratch_512 =
                (byte *)XMALLOC(RNG_HEALTH_TEST_CHECK_SIZE_SHA512, rng->heap,
                                DYNAMIC_TYPE_TMP_BUFFER);
            if (rng->health_check_scratch_512 == NULL) {
                ret = MEMORY_E;
                rng->status = DRBG_FAILED;
            }
        }
    #endif /* WOLFSSL_SMALL_STACK_CACHE */
    } /* WC_DRBG_SHA512 */
#endif /* WOLFSSL_DRBG_SHA512 */

    /* newSeed_buf shared by both DRBG types for PollAndReSeed */
#ifdef WOLFSSL_SMALL_STACK_CACHE
    if (ret == 0) {
        rng->newSeed_buf = (byte*)XMALLOC(SEED_SZ + SEED_BLOCK_SZ, rng->heap,
                           DYNAMIC_TYPE_SEED);
        if (rng->newSeed_buf == NULL) {
            ret = MEMORY_E;
            rng->status = DRBG_FAILED;
        }
    }
#endif /* WOLFSSL_SMALL_STACK_CACHE */

    if (ret == 0) {
        ret = wc_RNG_HealthTestLocal(rng, 0, rng->heap, devId);
        if (ret != 0) {
        #if defined(DEBUG_WOLFSSL)
            WOLFSSL_MSG_EX("wc_RNG_HealthTestLocal failed err = %d", ret);
        #endif
        }
    }

    #ifdef WOLFSSL_SMALL_STACK
    if (ret == 0) {
        WC_ALLOC_VAR_EX(seed, byte, MAX_SEED_SZ, rng->heap, DYNAMIC_TYPE_SEED,
                        WC_DO_NOTHING);
        if (seed == NULL) {
            ret = MEMORY_E;
            rng->status = DRBG_FAILED;
        }
    }
    #endif

    if (ret != 0) {
#if defined(DEBUG_WOLFSSL)
        WOLFSSL_MSG_EX("_InitRng failed. err = %d", ret);
#endif
    }
    else {
        if (seedRng != NULL) {
            /* RBGC spawn: draw the seed material from the parent DRBG's
             * generate function in place of the module's seed source -- the SP
             * 800-90C RBG chain construction.  The root DRBG is implicitly
             * healthy, so the seed Health test is omitted; all subsequent
             * handling (seed byte accounting, instantiate, failure disposition)
             * is then identical to the primary seed path. */
            ret = wc_RNG_GenerateBlock(seedRng, seed, seedSz);
        }
        else {
#ifdef WC_RNG_SEED_CB
            if (seedCb == NULL) {
                ret = DRBG_NO_SEED_CB;
            }
            else {
                ret = seedCb(&rng->seed, seed, seedSz);
                if (ret != 0) {
#ifdef WC_VERBOSE_RNG
                    WOLFSSL_DEBUG_PRINTF(
                        "ERROR: seedCb in _InitRng() failed with err = %d",
                        ret);
#endif
                    ret = DRBG_FAILURE;
                }
            }
#else
            ret = wc_GenerateSeed(&rng->seed, seed, seedSz);
#endif /* WC_RNG_SEED_CB */
        }

#ifdef WOLFSSL_CHECK_MEM_ZERO
        /* seed now holds entropy; register across DRBG instantiation */
        wc_MemZero_Add("_InitRng seed", seed, seedSz);
#endif

        if (ret != 0) {
    #if defined(DEBUG_WOLFSSL)
            WOLFSSL_MSG_EX("Seed generation failed... %d", ret);
    #elif defined(WC_VERBOSE_RNG)
            WOLFSSL_DEBUG_PRINTF(
                "ERROR: seed acquisition in _InitRng() failed with err %d",
                ret);
    #endif
            ret = DRBG_FAILURE;
            rng->status = DRBG_FAILED;
        }

        /* Health-check the primary seed -- RBGC seed is implicitly healthy. */

        if ((ret == 0) && (seedRng == NULL)) {
            ret = wc_RNG_TestSeed(seed, seedSz);
            #if defined(DEBUG_WOLFSSL)
            if (ret != 0) {
                WOLFSSL_MSG_EX("wc_RNG_TestSeed failed... %d", ret);
            }
            #elif defined(WC_VERBOSE_RNG)
            if (ret != DRBG_SUCCESS) {
                WOLFSSL_DEBUG_PRINTF(
                    "ERROR: wc_RNG_TestSeed() in _InitRng() returned err %d.",
                    ret);
            }
            #endif
        }

        /* Instantiate the DRBG */

        if (ret == DRBG_SUCCESS) {
#ifndef NO_SHA256
            if (rng->drbgType == WC_DRBG_SHA256)
                ret = Hash_DRBG_Instantiate((DRBG_internal *)rng->drbg,
                #if defined(HAVE_FIPS) || !defined(WOLFSSL_RNG_USE_FULL_SEED)
                            seed + SEED_BLOCK_SZ, seedSz - SEED_BLOCK_SZ,
                #else
                            seed, seedSz,
                #endif
                            nonce, nonceSz, perso, persoSz, rng->heap, devId);
#endif
#ifdef WOLFSSL_DRBG_SHA512
            if (rng->drbgType == WC_DRBG_SHA512)
                ret = Hash512_DRBG_Instantiate(
                    (DRBG_SHA512_internal *)rng->drbg512,
                #if defined(HAVE_FIPS) || !defined(WOLFSSL_RNG_USE_FULL_SEED)
                    seed + SEED_BLOCK_SZ, seedSz - SEED_BLOCK_SZ,
                #else
                    seed, seedSz,
                #endif
                    nonce, nonceSz, perso, persoSz, rng->heap, devId);
#endif
            if (ret == 0)
                drbg_instantiated = 1;
        }
    } /* ret == 0 */

    /* Unconditionally burn the seed data. */

    #ifdef WOLFSSL_SMALL_STACK
    if (seed)
    #endif
    {
        ForceZero(seed, seedSz);
    #if !defined(WOLFSSL_SMALL_STACK) && defined(WOLFSSL_CHECK_MEM_ZERO)
        /* heap build's WC_FREE_VAR_EX/XFREE auto-checks; stack build needs it */
        wc_MemZero_Check(seed, seedSz);
    #endif
    }
    WC_FREE_VAR_EX(seed, rng->heap, DYNAMIC_TYPE_SEED);

    if (ret == DRBG_SUCCESS) {
#ifdef WOLFSSL_CHECK_MEM_ZERO
    #ifndef NO_SHA256
        if (rng->drbgType == WC_DRBG_SHA256) {
            struct DRBG_internal* drbg = (struct DRBG_internal*)rng->drbg;
            wc_MemZero_Add("DRBG V", &drbg->V, sizeof(drbg->V));
            wc_MemZero_Add("DRBG C", &drbg->C, sizeof(drbg->C));
        }
    #endif
#endif

        rng->status = DRBG_OK;
        ret = 0;
    }
    else if (ret == WC_NO_ERR_TRACE(DRBG_CONT_FAILURE)) {
        rng->status = DRBG_CONT_FAILED;
        ret = DRBG_CONT_FIPS_E;
    }
    else if (ret == WC_NO_ERR_TRACE(DRBG_FAILURE)) {
        rng->status = DRBG_FAILED;
        ret = RNG_FAILURE_E;
    }
    else {
        rng->status = DRBG_FAILED;
    }
#endif /* HAVE_HASHDRBG */
#endif /* CUSTOM_RAND_GENERATE_BLOCK */

#ifdef WC_RNG_HAVE_NEXT_SEED
    if ((ret == 0) &&
        (flags & WC_RNG_INIT_FLAG_RECOVER_AND_PROMOTE_FROM_NEXT_SEED))
    {
        rng->flags |= WC_RNG_FLAG_RECOVER_AND_PROMOTE_FROM_NEXT_SEED;
    }
#endif
    if ((ret == 0) && (flags & WC_RNG_INIT_FLAG_USE_FULL_MUTEX)) {
#ifdef WC_RNG_HAVE_LOCK_FULL_MUTEX
        /* deliberately the last init step: no failure path can strand an
         * initialized mutex. */
        ret = wc_InitMutex(&rng->mutex);
        if (ret == 0) {
            rng->flags |= WC_RNG_FLAG_FULL_MUTEX;
            if (flags & WC_RNG_INIT_FLAG_LOCK_INITIALLY) {
                /* born held at both layers: the constructor's caller holds
                 * the whole latch, mutex included. */
                ret = wc_LockMutex(&rng->mutex);
            }
        }
#endif
    }

    if (ret != 0) {
    #ifdef WC_RNG_HAVE_LOCK_FULL_MUTEX
        if (rng->flags & WC_RNG_FLAG_FULL_MUTEX) {
            /* covers wc_LockMutex() failure after successful
             * wc_InitMutex() (WC_RNG_INIT_FLAG_LOCK_INITIALLY). */
            (void)wc_FreeMutex(&rng->mutex);
            rng->flags &= ~WC_RNG_FLAG_FULL_MUTEX;
        }
    #endif
    #if defined(HAVE_HASHDRBG) && !defined(CUSTOM_RAND_GENERATE_BLOCK)
    #ifndef NO_SHA256
        if (rng->drbgType == WC_DRBG_SHA256) {
            if (drbg_instantiated) {
                (void)Hash_DRBG_Uninstantiate(
                    (DRBG_internal *)rng->drbg);
            }
            #if !defined(WOLFSSL_NO_MALLOC) || defined(WOLFSSL_STATIC_MEMORY)
            XFREE(rng->drbg, rng->heap, DYNAMIC_TYPE_RNG);
            #endif
            rng->drbg = NULL;
            #ifdef WOLFSSL_SMALL_STACK_CACHE
            XFREE(rng->health_check_scratch, rng->heap,
                   DYNAMIC_TYPE_TMP_BUFFER);
            rng->health_check_scratch = NULL;
            if (drbg_scratch_instantiated)
                (void)Hash_DRBG_Uninstantiate(
                    (DRBG_internal *)rng->drbg_scratch);
            XFREE(rng->drbg_scratch, rng->heap, DYNAMIC_TYPE_RNG);
            rng->drbg_scratch = NULL;
            #endif /* WOLFSSL_SMALL_STACK_CACHE */
        }
    #endif /* !NO_SHA256 */
    #ifdef WOLFSSL_DRBG_SHA512
        if (rng->drbgType == WC_DRBG_SHA512) {
            if (drbg_instantiated) {
                (void)Hash512_DRBG_Uninstantiate(
                    (DRBG_SHA512_internal *)rng->drbg512);
            }
            #if !defined(WOLFSSL_NO_MALLOC) || defined(WOLFSSL_STATIC_MEMORY)
            XFREE(rng->drbg512, rng->heap, DYNAMIC_TYPE_RNG);
            #endif
            rng->drbg512 = NULL;
            #ifdef WOLFSSL_SMALL_STACK_CACHE
            XFREE(rng->health_check_scratch_512, rng->heap,
                   DYNAMIC_TYPE_TMP_BUFFER);
            rng->health_check_scratch_512 = NULL;
            if (drbg_scratch_instantiated)
                (void)Hash512_DRBG_Uninstantiate(rng->drbg512_scratch);
            XFREE(rng->drbg512_scratch, rng->heap, DYNAMIC_TYPE_RNG);
            rng->drbg512_scratch = NULL;
            #endif /* WOLFSSL_SMALL_STACK_CACHE */
        }
    #endif /* WOLFSSL_DRBG_SHA512 */
    #ifdef WOLFSSL_SMALL_STACK_CACHE
        XFREE(rng->newSeed_buf, rng->heap, DYNAMIC_TYPE_SEED);
        rng->newSeed_buf = NULL;
    #endif
    #endif /* HAVE_HASHDRBG && !CUSTOM_RAND_GENERATE_BLOCK */
    }

#ifdef WC_RNG_HAVE_AUTO_LOCK
    if ((ret == 0) && !(flags & WC_RNG_INIT_FLAG_NO_AUTO_LOCK) &&
        (WC_RNG_AUTO_LOCK_DEFAULT ||
         (flags & WC_RNG_INIT_FLAG_USE_AUTO_LOCK))) {
        ret = RngAutoLockInit(rng);
        if (ret != 0)
            (void)wc_FreeRng(rng);
    }
#endif
    return ret;
}


WOLFSSL_ABI
WC_RNG* wc_rng_new(byte* nonce, word32 nonceSz, void* heap)
{
    int ret = 0;
    WC_RNG* rng = NULL;

    /* Assume if WC_USE_DEVID it is intended for default usage */
#ifdef WC_USE_DEVID
    ret = wc_rng_new_ex(&rng, nonce, nonceSz, heap, WC_USE_DEVID);
#else
    ret = wc_rng_new_ex(&rng, nonce, nonceSz, heap, INVALID_DEVID);
#endif

    if (ret != 0) {
        return NULL;
    }

    return rng;
}


int wc_rng_new_ex(WC_RNG **rng, byte* nonce, word32 nonceSz,
                  void* heap, int devId)
{
    int ret;

    if (rng == NULL) {
        return BAD_FUNC_ARG;
    }

    *rng = (WC_RNG*)XMALLOC(sizeof(WC_RNG), heap, DYNAMIC_TYPE_RNG);
    if (*rng == NULL) {
        return MEMORY_E;
    }

    ret = _InitRng(*rng, nonce, nonceSz, NULL, 0, heap, devId, NULL,
                   WC_RNG_INIT_FLAG_NONE);
    if (ret != 0) {
        XFREE(*rng, heap, DYNAMIC_TYPE_RNG);
        *rng = NULL;
    }

    return ret;
}


WOLFSSL_ABI
void wc_rng_free(WC_RNG* rng)
{
    if (rng) {
        void* heap = rng->heap;

        wc_FreeRng(rng);
        ForceZero(rng, sizeof(WC_RNG));
        XFREE(rng, heap, DYNAMIC_TYPE_RNG);
        (void)heap;
    }
}

WOLFSSL_ABI
int wc_InitRng(WC_RNG* rng)
{
    return _InitRng(rng, NULL, 0, NULL, 0, NULL, INVALID_DEVID, NULL,
                    WC_RNG_INIT_FLAG_NONE);
}


int wc_InitRng_ex(WC_RNG* rng, void* heap, int devId)
{
    return _InitRng(rng, NULL, 0, NULL, 0, heap, devId, NULL,
                    WC_RNG_INIT_FLAG_NONE);
}


int wc_InitRngNonce(WC_RNG* rng, const byte* nonce, word32 nonceSz)
{
    return _InitRng(rng, nonce, nonceSz, NULL, 0, NULL, INVALID_DEVID, NULL,
                    WC_RNG_INIT_FLAG_NONE);
}


int wc_InitRngNonce_ex(WC_RNG* rng, const byte* nonce, word32 nonceSz,
                       void* heap, int devId)
{
    return _InitRng(rng, nonce, nonceSz, NULL, 0, heap, devId, NULL,
                    WC_RNG_INIT_FLAG_NONE);
}

int wc_InitRng_ex2(WC_RNG* rng, void* heap, int devId, word32 flags)
{
    return _InitRng(rng, NULL, 0, NULL, 0, heap, devId, NULL, flags);
}

int wc_InitRngNonce_ex2(WC_RNG* rng, const byte* nonce, word32 nonceSz,
                        const byte *perso, word32 persoSz,
                        void* heap, int devId, word32 flags)
{
    return _InitRng(rng, nonce, nonceSz, perso, persoSz,
                    heap, devId, NULL, flags);
}

#if defined(HAVE_GETPID) && !defined(WOLFSSL_NO_GETPID)

#if defined(HAVE_HASHDRBG) && !defined(CUSTOM_RAND_GENERATE_BLOCK)
static WARN_UNUSED_RESULT int PollAndReSeed(WC_RNG* rng, const byte* additional,
                         word32 additionalSz);
#endif

/* rng_pid_change_check() is used by wc_RNG_Pool_Extract(),
 * wc_RNG_DRBG_NextSeedNow_Nonce(), and wc_RNG_GenerateBlock(), to assure that
 * the RNG is freshly seeded after a fork(), to avoid seeding or generating from
 * duplicated internal state.
 */
static WARN_UNUSED_RESULT WC_MAYBE_UNUSED int rng_pid_change_check(WC_RNG* rng) {
    int ret = 0;
    int my_pid = getpid();

    if (rng->pid == my_pid)
        return 0;

    rng->pid = my_pid;

#if defined(HAVE_HASHDRBG) && !defined(CUSTOM_RAND_GENERATE_BLOCK)
    ret = PollAndReSeed(rng, NULL, 0);
    if (ret != DRBG_SUCCESS) {
        rng->status = DRBG_FAILED;
        ret = RNG_FAILURE_E;
    }
#endif

#ifdef WC_RNG_HAVE_POOL
    {
        int ret2 = PoolPurge(rng);
        if ((ret == 0) &&
            (ret2 != 0) &&
            (ret2 != WC_NO_ERR_TRACE(ALREADY_E)))
        {
            ret = ret2;
        }
    }
#endif

#ifdef WC_RNG_HAVE_NEXT_SEED
    WOLFSSL_ATOMIC_STORE(rng->nextStirLen,
                         WC_DRBG_NEXT_SEED_EMPTY);
    #ifndef NO_SHA256
    if ((rng->drbgType == WC_DRBG_SHA256) && (rng->drbg != NULL)) {
        int ret2 = NextSeedPurge(&((DRBG_internal *)rng->drbg)->nextSeedLen,
            ((DRBG_internal *)rng->drbg)->nextSeed,
            (word32)sizeof(((DRBG_internal *)rng->drbg)->nextSeed));
        if ((ret == 0) &&
            (ret2 != 0) &&
            (ret2 != WC_NO_ERR_TRACE(ALREADY_E)))
        {
            ret = ret2;
        }
    }
    #endif
    #ifdef WOLFSSL_DRBG_SHA512
    if ((rng->drbgType == WC_DRBG_SHA512) && (rng->drbg512 != NULL)) {
        int ret2 =
            NextSeedPurge(&((DRBG_SHA512_internal *)rng->drbg512)->nextSeedLen,
            ((DRBG_SHA512_internal *)rng->drbg512)->nextSeed,
            (word32)sizeof(((DRBG_SHA512_internal *)rng->drbg512)->nextSeed));
        if ((ret == 0) &&
            (ret2 != 0) &&
            (ret2 != WC_NO_ERR_TRACE(ALREADY_E)))
        {
            ret = ret2;
        }
    }
    #endif
#endif /* WC_RNG_HAVE_NEXT_SEED */

    return ret;
}
#endif /* HAVE_GETPID && !WOLFSSL_NO_GETPID */

#ifdef WC_RNG_HAVE_LOCK

/* Note, in CAS updates here, the stored value derives only from expected and
 * the caller's arguments, never from a prior load.  This assures no race with
 * unlocked changes to any bits.
 */

int wc_RNG_lock_get(WC_RNG* rng, WC_RNG_lock_arg_t extra_bits)
{
    WC_RNG_lock_arg_t cur_lock;

    if (rng == NULL)
        return BAD_FUNC_ARG;

#ifdef WC_RNG_HAVE_LOCK_FULL_MUTEX
    /* outermost blocking layer, when constructed with _USE_FULL_MUTEX:
     * contending getters sleep here rather than seeing BUSY_E. */
    if (rng->flags & WC_RNG_FLAG_FULL_MUTEX) {
        if (wc_LockMutex(&rng->mutex) != 0) {
            #ifdef WC_RNG_DEBUG_STATS
            ++rng->_stats_locks_refused; /* racy */
            #endif
            return BAD_MUTEX_E;
        }
    }
#endif

    /* extra_bits is allowed to assert WC_RNG_LOCK_REQUIRED, which is in the
     * reserved section. */
    extra_bits &= ~((1U << WC_RNG_LOCK_EXTRA_SHIFT) - 1U) |
        WC_RNG_LOCK_REQUIRED;

    cur_lock = WOLFSSL_ATOMIC_LOAD(rng->lock);

    if (cur_lock & WC_RNG_LOCK_ENTROPY_INVALIDATED) {
#ifdef WC_RNG_HAVE_NEXT_SEED
        WC_ATOMIC_INT_ARG NextSeedCurrent;
        if ((rng->flags & WC_RNG_FLAG_RECOVER_AND_PROMOTE_FROM_NEXT_SEED) &&
            (wc_RNG_DRBG_NextSeedCurrent(rng, &NextSeedCurrent) == 0) &&
            (NextSeedCurrent == WC_DRBG_NEXT_SEED_READY))
        {
            /* cheap inline recovery available. */
        }
        else
#endif
        {
            #ifdef WC_RNG_DEBUG_STATS
            ++rng->_stats_locks_refused; /* racy */
            #endif
#ifdef WC_RNG_HAVE_LOCK_FULL_MUTEX
            if (rng->flags & WC_RNG_FLAG_FULL_MUTEX)
                (void)wc_UnLockMutex(&rng->mutex);
#endif
            return NEEDS_RECOVERY_E;
        }
    }

    if ((! (cur_lock & WC_RNG_LOCK_HELD)) &&
        (wolfSSL_Atomic_Uint_CompareExchange(
            &rng->lock, &cur_lock,
            cur_lock | WC_RNG_LOCK_HELD | extra_bits)))
    {
        #ifdef WC_RNG_DEBUG_STATS
        ++rng->_stats_locks_taken;
        #endif

        /* If we arrived here via _RECOVER_AND_PROMOTE_FROM_NEXT_SEED with a
         * pending NextSeed, there is a finite though minuscule chance that a
         * second invalidation left the RNG without a banked seed to consume.
         * In that case, the holder's generate falls through to the regular
         * inline forced-reseed machinery.  This is the same outcome as an
         * invalidation landing immediately after a successful acquire.
         */

        return 0;
    }

    #ifdef WC_RNG_DEBUG_STATS
    ++rng->_stats_locks_refused;
    #endif

#ifdef WC_RNG_HAVE_LOCK_FULL_MUTEX
    /* CAS failure with the mutex held means a non-mutex claimant holds
     * the latch (mixed-discipline use); back out the mutex. */
    if (rng->flags & WC_RNG_FLAG_FULL_MUTEX)
        (void)wc_UnLockMutex(&rng->mutex);
#endif

    if (cur_lock & WC_RNG_LOCK_HELD)
        return BUSY_E;
    else if (cur_lock & WC_RNG_LOCK_ENTROPY_INVALIDATED)
        return NEEDS_RECOVERY_E;
    else /* not reachable */
        return UNEXPECTED_STATE_E;
}

int wc_RNG_lock_get_conditional(WC_RNG* rng,
                                WC_RNG_lock_arg_t expected_extra_bits,
                                WC_RNG_lock_arg_t want_extra_bits)
{
    WC_RNG_lock_arg_t cur_lock, expected;

    if (rng == NULL)
        return BAD_FUNC_ARG;

#ifdef WC_RNG_HAVE_LOCK_FULL_MUTEX
    /* outermost blocking layer, when constructed with _USE_FULL_MUTEX:
     * contending getters sleep here rather than seeing BUSY_E. */
    if (rng->flags & WC_RNG_FLAG_FULL_MUTEX) {
        if (wc_LockMutex(&rng->mutex) != 0) {
            #ifdef WC_RNG_DEBUG_STATS
            ++rng->_stats_locks_refused; /* racy */
            #endif
            return BAD_MUTEX_E;
        }
    }
#endif

    /* *_extra_bits are allowed to assert WC_RNG_LOCK_REQUIRED, which is in the
     * reserved section.  Additionally, expected_extra_bits is allowed to
     * include WC_RNG_LOCK_ENTROPY_INVALIDATED, for purposes of recovery. */
    expected_extra_bits &= ~((1U << WC_RNG_LOCK_EXTRA_SHIFT) - 1U) |
        WC_RNG_LOCK_REQUIRED | WC_RNG_LOCK_ENTROPY_INVALIDATED;
    want_extra_bits &= ~((1U << WC_RNG_LOCK_EXTRA_SHIFT) - 1U) |
        WC_RNG_LOCK_REQUIRED;

    cur_lock = WOLFSSL_ATOMIC_LOAD(rng->lock);

    if ((cur_lock & WC_RNG_LOCK_ENTROPY_INVALIDATED) &&
        (! (expected_extra_bits & WC_RNG_LOCK_ENTROPY_INVALIDATED)))
    {
        #ifdef WC_RNG_DEBUG_STATS
        ++rng->_stats_locks_refused; /* racy */
        #endif
#ifdef WC_RNG_HAVE_LOCK_FULL_MUTEX
        if (rng->flags & WC_RNG_FLAG_FULL_MUTEX)
            (void)wc_UnLockMutex(&rng->mutex);
#endif
        return NEEDS_RECOVERY_E;
    }

    expected = (cur_lock & (((1U << WC_RNG_LOCK_EXTRA_SHIFT) - 1U) &
                            ~(WC_RNG_LOCK_HELD |
                              WC_RNG_LOCK_ENTROPY_INVALIDATED))) |
        expected_extra_bits;

    if ((! (cur_lock & WC_RNG_LOCK_HELD)) &&
        (wolfSSL_Atomic_Uint_CompareExchange(
            &rng->lock, &expected,
            expected | WC_RNG_LOCK_HELD | want_extra_bits)))
    {
        #ifdef WC_RNG_DEBUG_STATS
        ++rng->_stats_locks_taken;
        #endif
        return 0;
    }

    #ifdef WC_RNG_DEBUG_STATS
    ++rng->_stats_locks_refused; /* racy */
    #endif

#ifdef WC_RNG_HAVE_LOCK_FULL_MUTEX
    /* CAS failure with the mutex held means a non-mutex claimant holds
     * the latch (mixed-discipline use); back out the mutex. */
    if (rng->flags & WC_RNG_FLAG_FULL_MUTEX)
        (void)wc_UnLockMutex(&rng->mutex);
#endif

    if ((cur_lock & WC_RNG_LOCK_ENTROPY_INVALIDATED) !=
        (expected & WC_RNG_LOCK_ENTROPY_INVALIDATED))
    {
        return NEEDS_RECOVERY_E;
    }
    else if (expected & WC_RNG_LOCK_HELD)
        return BUSY_E;
    else
        return UNEXPECTED_STATE_E;
}

int wc_RNG_lock_put(WC_RNG* rng, WC_RNG_lock_arg_t extra_bits)
{
    WC_RNG_lock_arg_t cur_lock, new_lock;
    int cas_ret;
    if (rng == NULL)
        return BAD_FUNC_ARG;
    cur_lock = WOLFSSL_ATOMIC_LOAD(rng->lock);
    if (! (cur_lock & WC_RNG_LOCK_HELD))
        return OBJECT_NOT_LOCKED_E;

    #ifdef WC_RNG_DEBUG_STATS
    ++rng->_stats_locks_released;
    #endif

    WC_CAS_WITH_RETRY_BEGIN(&rng->lock, cur_lock, cas_ret) {
        new_lock = cur_lock & (((1U << WC_RNG_LOCK_EXTRA_SHIFT) - 1U) &
                               ~WC_RNG_LOCK_HELD);
        /* extra_bits is allowed to assert WC_RNG_LOCK_REQUIRED, which is in the
         * reserved section. */
        extra_bits &= ~((1U << WC_RNG_LOCK_EXTRA_SHIFT) - 1U) |
            WC_RNG_LOCK_REQUIRED;
        new_lock |= extra_bits;
        WC_CAS_WITH_RETRY_LOOP_FOREVER(wolfSSL_Atomic_Uint_CompareExchange,
                                      &rng->lock, cur_lock, new_lock, cas_ret);
    } WC_CAS_WITH_RETRY_END;

    if (cas_ret != 0) {
        /* Aborted release (a port's retry clause): the latch is still ours
         * and new_lock was never installed.  Keep ownership consistent --
         * mutex included -- and percolate so the caller can retry the
         * put. */
        return cas_ret;
    }

#ifdef WC_RNG_HAVE_LOCK_FULL_MUTEX
    if (rng->flags & WC_RNG_FLAG_FULL_MUTEX)
        (void)wc_UnLockMutex(&rng->mutex);
#endif

    if (new_lock & WC_RNG_LOCK_ENTROPY_INVALIDATED)
        return NEEDS_RECOVERY_E;
    else
        return 0;
}

int wc_RNG_lock_put_conditional(WC_RNG* rng,
                                WC_RNG_lock_arg_t expected_extra_bits,
                                WC_RNG_lock_arg_t want_extra_bits)
{
    int cas_ret;
    WC_CAS_WITH_RETRY_EXTRA_DECLS;
    WC_RNG_lock_arg_t cur_lock, expected, new_lock;

    if (rng == NULL)
        return BAD_FUNC_ARG;

    cur_lock = WOLFSSL_ATOMIC_LOAD(rng->lock);
    if (! (cur_lock & WC_RNG_LOCK_HELD))
        return OBJECT_NOT_LOCKED_E;

    #ifdef WC_RNG_DEBUG_STATS
    ++rng->_stats_locks_released;
    #endif

    /* Note this CAS loop doesn't use WC_CAS_WITH_RETRY_*() (non-conformant code
     * pattern), so the WC_CAS_WITH_RETRY_* hook macros are invoked directly. */
    for (;;) {
        new_lock = cur_lock & (((1U << WC_RNG_LOCK_EXTRA_SHIFT) - 1U) &
                               ~WC_RNG_LOCK_HELD);
        /* want_extra_bits is allowed to assert WC_RNG_LOCK_REQUIRED, which is
         * in the reserved section. */
        want_extra_bits &= ~((1U << WC_RNG_LOCK_EXTRA_SHIFT) - 1U) |
            WC_RNG_LOCK_REQUIRED;
        new_lock |= want_extra_bits;

        expected = WC_RNG_LOCK_HELD | expected_extra_bits |
            (cur_lock & WC_RNG_LOCK_ENTROPY_INVALIDATED);

        new_lock |= (expected_extra_bits & WC_RNG_LOCK_REQUIRED) |
            (cur_lock & WC_RNG_LOCK_ENTROPY_INVALIDATED);

        /* release preserves the sticky bit if the caller reports it held */
        if (wolfSSL_Atomic_Uint_CompareExchange(
                &rng->lock, &expected,
                new_lock))
        {
#ifdef WC_RNG_HAVE_LOCK_FULL_MUTEX
            if (rng->flags & WC_RNG_FLAG_FULL_MUTEX)
                (void)wc_UnLockMutex(&rng->mutex);
#endif
            if (new_lock & WC_RNG_LOCK_ENTROPY_INVALIDATED)
                return NEEDS_RECOVERY_E;
            else
                return 0;
        }
        if ((expected & ((1U << WC_RNG_LOCK_EXTRA_SHIFT) - 1U)) !=
            (expected_extra_bits & ((1U << WC_RNG_LOCK_EXTRA_SHIFT) - 1U)))
        {
            break;
        }

        cur_lock = expected;

        cas_ret = WC_CAS_WITH_RETRY_FOREVER_CLAUSE;
        if (cas_ret != 0)
            return cas_ret;
        WC_CAS_WITH_RETRY_ITER_CLAUSE(&rng->lock, cur_lock, new_lock, cas_ret);
    }

    /* conditional release failed: the caller is still the holder, at both
     * layers -- the mutex stays held. */

    #ifdef WC_RNG_DEBUG_STATS
    --rng->_stats_locks_released;
    #endif

    return UNEXPECTED_STATE_E;
}

int wc_RNG_lock_read(WC_RNG* rng, WC_RNG_lock_arg_t* state)
{
    if ((rng == NULL) || (state == NULL))
        return BAD_FUNC_ARG;
    *state = WOLFSSL_ATOMIC_LOAD(rng->lock);
    return 0;
}

int wc_RNG_lock_set_extra(WC_RNG* rng, WC_RNG_lock_arg_t extra_bits)
{
    WC_RNG_lock_arg_t cur_lock, new_lock;
    int cas_ret;
    if (rng == NULL)
        return BAD_FUNC_ARG;
    cur_lock = WOLFSSL_ATOMIC_LOAD(rng->lock);

    WC_CAS_WITH_RETRY_BEGIN(&rng->lock, cur_lock, cas_ret) {
        new_lock = cur_lock & ((1U << WC_RNG_LOCK_EXTRA_SHIFT) - 1U);
        /* extra_bits is allowed to assert WC_RNG_LOCK_REQUIRED, which is in the
         * reserved section. */
        extra_bits &= ~((1U << WC_RNG_LOCK_EXTRA_SHIFT) - 1U) |
            WC_RNG_LOCK_REQUIRED;
        new_lock |= extra_bits;

        WC_CAS_WITH_RETRY_LOOP_FOREVER(wolfSSL_Atomic_Uint_CompareExchange,
                                      &rng->lock, cur_lock, new_lock, cas_ret);
    } WC_CAS_WITH_RETRY_END;
    /* 0 unless a port's retry clause aborted; the lock word is then
     * untouched, so percolation is the whole handling. */
    return cas_ret;
}

int wc_RNG_lock_add_extra(WC_RNG* rng, WC_RNG_lock_arg_t extra_bits)
{
    WC_RNG_lock_arg_t cur_lock;
    int cas_ret;
    if (rng == NULL)
        return BAD_FUNC_ARG;
    cur_lock = WOLFSSL_ATOMIC_LOAD(rng->lock);

    /* extra_bits is allowed to assert WC_RNG_LOCK_REQUIRED, which is in the
     * reserved section. */
    extra_bits &= ~((1U << WC_RNG_LOCK_EXTRA_SHIFT) - 1U) |
        WC_RNG_LOCK_REQUIRED;

    WC_CAS_WITH_RETRY_BEGIN(&rng->lock, cur_lock, cas_ret) {
        WC_CAS_WITH_RETRY_LOOP_FOREVER(wolfSSL_Atomic_Uint_CompareExchange,
                                      &rng->lock, cur_lock,
                                      cur_lock | extra_bits, cas_ret);
    } WC_CAS_WITH_RETRY_END;
    /* see wc_RNG_lock_set_extra() re nonzero cas_ret. */
    return cas_ret;
}

int wc_RNG_lock_clear_extra(WC_RNG* rng, WC_RNG_lock_arg_t extra_bits)
{
    WC_RNG_lock_arg_t cur_lock;
    int cas_ret;
    if (rng == NULL)
        return BAD_FUNC_ARG;
    if (extra_bits & WC_RNG_LOCK_REQUIRED) {
        /* WC_RNG_LOCK_REQUIRED is sticky by contract */
        return BAD_FUNC_ARG;
    }
    cur_lock = WOLFSSL_ATOMIC_LOAD(rng->lock);

    extra_bits &= ~((1U << WC_RNG_LOCK_EXTRA_SHIFT) - 1U);

    WC_CAS_WITH_RETRY_BEGIN(&rng->lock, cur_lock, cas_ret) {
        WC_CAS_WITH_RETRY_LOOP_FOREVER(wolfSSL_Atomic_Uint_CompareExchange,
                                      &rng->lock, cur_lock,
                                      cur_lock & ~extra_bits, cas_ret);
    } WC_CAS_WITH_RETRY_END;
    /* see wc_RNG_lock_set_extra() re nonzero cas_ret. */
    return cas_ret;
}

#ifdef HAVE_HASHDRBG
WOLFSSL_API int wc_RNG_invalidate_entropy(WC_RNG* rng) {
    WC_RNG_lock_arg_t cur_lock;
    int ret;

    if (rng == NULL)
        return BAD_FUNC_ARG;

    /* If no lock is held, either the RNG is in use without a lock, in which
     * case the reseedCtr is the only way to force invalidation semantics on the
     * user, or it is not in use at all and scheduling a reseed is harmless.
     *
     * If a lock is held, the holder will learn of the invalidation at unlock
     * time, and will implement its own mitigation strategy.  We do not force it
     * into a synchronous reseed.
     *
     * In either case, the state purges here are best effort.  With
     * WC_RNG_HAVE_LOCK, these purges are repeated, strictly serialized against
     * concurrent recovery attempts, in Hash_DRBG_Reseed() (the sole recovery
     * path from _ENTROPY_INVALIDATED).
     */
    ret = wc_RNG_DRBG_ScheduleReseed(rng);
    if (ret == WC_NO_ERR_TRACE(WRONG_TYPE_OBJECT_E)) {
        /* No DRBG (direct-RDRAND et al.): nothing to schedule, and nothing
         * whose staleness the latch would mark -- not a condemnable
         * failure.  Any applicable auxiliary-state purges below still
         * run. */
        ret = 0;
    }

#ifdef WC_RNG_HAVE_POOL
    {
        int ret2 = PoolPurge(rng);
        if ((ret2 != 0) && (ret == 0))
            ret = ret2;
    }
#endif
#ifdef WC_RNG_HAVE_NEXT_SEED
    WOLFSSL_ATOMIC_STORE(rng->nextStirLen,
                         WC_DRBG_NEXT_SEED_EMPTY);
#ifndef NO_SHA256
    if ((rng->drbgType == WC_DRBG_SHA256) && (rng->drbg != NULL)) {
        int ret2 = NextSeedPurge(&((DRBG_internal *)rng->drbg)->nextSeedLen,
            ((DRBG_internal *)rng->drbg)->nextSeed,
            (word32)sizeof(((DRBG_internal *)rng->drbg)->nextSeed));
        if ((ret2 != 0) &&
            (ret2 != WC_NO_ERR_TRACE(ALREADY_E)) &&
            (ret == 0))
        {
            ret = ret2;
        }
    }
#endif
#ifdef WOLFSSL_DRBG_SHA512
    if ((rng->drbgType == WC_DRBG_SHA512) && (rng->drbg512 != NULL)) {
        int ret2 =
            NextSeedPurge(&((DRBG_SHA512_internal *)rng->drbg512)->nextSeedLen,
            ((DRBG_SHA512_internal *)rng->drbg512)->nextSeed,
            (word32)sizeof(((DRBG_SHA512_internal *)rng->drbg512)->nextSeed));
        if ((ret2 != 0) &&
            (ret2 != WC_NO_ERR_TRACE(ALREADY_E)) &&
            (ret == 0))
        {
            ret = ret2;
        }
    }
#endif
#endif /* WC_RNG_HAVE_NEXT_SEED */

    /* Assert _ENTROPY_INVALIDATED last: latch-after-purge makes the latch a
     * provenance marker.  Any consumer that observes the latch observes
     * post-purge apertures, so a READY it then claims necessarily postdates
     * this event; a consumer that raced ahead of the latch loses its claim
     * to the purge above and is refused at its release CAS (see
     * wc_RNG_DRBG_NextSeedNow_Nonce()); and an event landing mid-reseed
     * strips _ENTROPY_RECOVERING here, so the recovery's exit CAS refuses
     * the clear.  No interleaving recovers from pre-event material. */

    {
        int cas_ret;
        WC_CAS_WITH_RETRY_BEGIN_INIT_CUR(&rng->lock, cur_lock, cas_ret) {
            WC_CAS_WITH_RETRY_LOOP_FOREVER(
                wolfSSL_Atomic_Uint_CompareExchange, &rng->lock, cur_lock,
                (cur_lock & ~WC_RNG_LOCK_ENTROPY_RECOVERING) |
                WC_RNG_LOCK_ENTROPY_INVALIDATED,
                cas_ret);
        } WC_CAS_WITH_RETRY_END;
        if ((cas_ret != 0) && (ret == 0))
            ret = cas_ret;
    }

    /* Postcondition: latch or condemn.  Zero return means _INVALIDATED is
     * asserted; any nonzero return leaves the latch down (it is asserted last,
     * above), so the instance is quarantined by counter saturation alone -- and
     * the reseedCtr is subject to lost-update races.  DRBG_FAILED is the
     * remaining stop no interleaving can lift: sticky until a full recovery.
     *
     * This is the one leaseless outsider write of DRBG_FAILED; the race against
     * a lease-holder is benign both ways (a completing reseed's OK overwrite
     * means the state was genuinely re-derived from post-event material; a
     * FAILED overwrite of OK costs one spurious reinit, never unsound output).
     * In the kernel build, bank instances are retired and recovered by the
     * entropy daemon's out-of-service pass; a leaf's owner sees hard
     * RNG_FAILURE_E and reinitializes.
     */
    if (ret != 0)
        rng->status = DRBG_FAILED;

    return ret;
}

#endif /* HAVE_HASHDRBG */
#endif /* WC_RNG_HAVE_LOCK */

#ifdef WC_RNG_HAVE_FREE_HOOK
/* This routine is used for mitigation of RNG cloning events, particularly by
 * hypervisors. */
WOLFSSL_API int wc_RNG_register_free_hook(WC_RNG* rng,
                                          wc_RNG_free_hook_cb_t free_hook,
                                          void *arg)
{
    if (rng == NULL)
        return BAD_FUNC_ARG;
    rng->free_hook = free_hook;
    rng->free_hook_arg = arg;
    return 0;
}
#endif /* WC_RNG_HAVE_FREE_HOOK */

#ifdef WC_RNG_HAVE_POOL

    /* In-boundary asynchronous DRBG output pool (wc_RNG_Pool_*()): a circular
     * buffer of pre-generated output, held and zeroized under the module's CSP
     * discipline and consumed destructively (each delivered or discarded byte
     * is burned).
     *
     * Writer state coherence is enforced with a CAS; reader exclusivity is
     * enforced by the umbrella WC_RNG.lock, or absent that, by caller contract.
     *
     * The reader is lock-free -- two plain loads of {head, epoch} bracketing
     * the copy, then a plain store of {tail, epoch} exclusively written by the
     * reader.  The writer CASes its publication, carrying the epoch it read; a
     * purge during its generate results in an epoch mismatch, whereupon BUSY_E
     * is returned to the caller.
     *
     * _Alloc() sizes the ring (2..32767 bytes), with positions running in [0,
     * 2*size) and packing into 16 bits.  _Collect() tops up the pool from rng's
     * own DRBG; _Collect2() tops dest's ring up from an independent src
     * instance, generating directly into the free span and publishing with a
     * single CAS -- callable WITHOUT any lease on dest (contending writers
     * return BUSY_E on CAS failure; the final write of every published byte is
     * certified DRBG output).  _Extract() (lease-holder only) delivers up to *n
     * bytes destructively, burning each byte on the way out, and fails closed
     * on an out-of-service DRBG; *n = 0 on empty, for fall-through to a direct
     * generate.  _Current() reports the published count (racy snapshot).  No
     * special free API: the ring lives until wc_FreeRng(), eliminating
     * deallocation races by construction.
     *
     * Two words track FIFO state:
     *
     *   poolHead = {head, epoch}   written by the writer (publish, CAS) and by
     *                               PoolPurge() (epoch bump, CAS)
     *   poolTail = {tail, epoch}   written by the reader alone, plain store
     *
     * Position and epoch share one word, so the pairs are always mutually
     * consistent -- there is no torn snapshot to reason about.
     *
     * head and tail are free-running positions in [0, 2*poolSize), advanced by
     * conditional subtraction -- no division, and no modulus constraint on
     * poolSize.  The writer publishes only into free space, so head can never
     * pass tail + poolSize and the two can never lap.
     *
     * wc_RNG_lock_put{,_conditional}() return NEEDS_RECOVERY_E to the reader if
     * an invalidation occurred after lock but before release (contingent on
     * WC_RNG_HAVE_LOCK).  State coherence for the lock-free writers and purgers
     * hinges on the CAS and epoch counter protocol in PoolPurge() and
     * wc_RNG_Pool_Collect2().
     *
     * The reader never writes poolHead and never CASes anything, leveraging
     * exclusivity enforced by WC_RNG.lock or arranged by caller contract.  It
     * brackets its copy with leading and trailing loads of poolHead and
     * compares the epoch: a purge that landed anywhere in between is caught,
     * providing for early, pre-unlock failure upon invalidation.  The epoch is
     * 16 bits, so defeating this early failure requires exactly k * 65536
     * purges (k a positive integer) inside one copy-and-burn of at most
     * poolSize bytes (implausible).
     *
     * PoolPurge() bumps epoch and touches nothing else.  It does not reset the
     * counters: leaving them monotonic keeps the reader's burn span [tail,
     * tail+m) and the writer's generate span [head, head+m') disjoint across
     * the event, so a purge can never cause one to erase the other's bytes.
     * Stale pre-purge material is discarded by the reader instead, which
     * resynchronizes tail to head on any epoch change -- whether it observed
     * the purge mid-serve or merely arrives afterwards.
     *
     * The writer still CASes, and its publication carries the epoch it read.  A
     * purge during its generate makes that CAS fail, and it abandons rather
     * than publishing material that predates the event.  This protocol is
     * airtight in the same sense as the credited next-seed aperture
     * (NextSeedPurge()): no invalidation can go unobserved by either side.
     *
     * If multiple writers simultaneously write to the pool, their inputs are
     * unpredictably but benignly interspersed, with one of the writers
     * successfully finalizing its write with a CAS, while the rest fail their
     * CAS and return BUSY_E.  Because all writers are tested for provenance
     * compatible with that of the destination RNG (particularly, by the stratum
     * test in wc_RNG_Pool_Collect2()), this interspersal is intrinsically
     * benign.  It can be trivially avoided by single-writer caller contract;
     * the fundamental benefit of this arrangement is the avoidance of an
     * initial frivolous CAS at entry to _Collect2().
     */

#define WC_RNG_POOL_POS(w)   ((word32)((word32)(w) & 0xFFFFU))
#define WC_RNG_POOL_EPOCH(w) ((word32)(((word32)(w) >> 16) & 0xFFFFU))
#define WC_RNG_POOL_PACK(pos, epoch)                                     \
    ((WC_ATOMIC_UINT_ARG)((((word32)(pos)) & 0xFFFFU) |                  \
                          ((((word32)(epoch)) & 0xFFFFU) << 16)))

wc_static_assert(sizeof(WC_ATOMIC_UINT_ARG) >= 4);

/* position -> ring index.  Positions run in [0, 2*poolSize). */
static WC_INLINE word32 PoolAt(word32 pos, word32 poolSize)
{
    return (pos >= poolSize) ? (pos - poolSize) : pos;
}

/* advance a position, wrapping at 2*poolSize. */
static WC_INLINE word32 PoolAdvance(word32 pos, word32 by, word32 poolSize)
{
    word32 lim = poolSize * 2U;
    pos += by;
    return (pos >= lim) ? (pos - lim) : pos;
}

static WC_INLINE word32 PoolUsed(word32 head, word32 tail, word32 poolSize)
{
    /* Note, the modular subtraction is unambiguous because the only publisher
     * (wc_RNG_Pool_Collect2()) carefully bounds itself to the free span, so
     * head never passes tail + poolSize. */
    return (head >= tail) ? (head - tail) : (head + (poolSize * 2U) - tail);
}

/* Wipe the retired span [tail, head): pooled bytes are finished DRBG output
 * at rest, and a retiring event (invalidation, fork, credited reseed) has a
 * sibling lineage that may serve its identical copy -- CSP by the doctrine
 * at NextSeedPurge().  Race-free by ownership: the single reader is the
 * only mover of tail, and writers write only past head. */
static WC_INLINE void PoolWipeRetired(WC_RNG *rng, word32 tail, word32 head)
{
    word32 used = PoolUsed(head, tail, (word32)rng->poolSize);
    word32 t = (tail >= (word32)rng->poolSize) ?
        (tail - (word32)rng->poolSize) : tail;
    word32 seg = (word32)rng->poolSize - t;
    if (seg > used)
        seg = used;
    if (seg > 0)
        ForceZero(rng->pool + t, seg);
    if (used > seg)
        ForceZero(rng->pool, used - seg);
}

/* Retire pooled output: any event after which pre-event bytes must not be
 * served -- state invalidation, fork, a credited reseed recovering from
 * invalidation, the reader's
 * fail-closed path.  Bumping epoch is the whole operation; see above for why
 * the counters are deliberately left alone. */
static WARN_UNUSED_RESULT int PoolPurge(WC_RNG* rng)
{
    WC_ATOMIC_UINT_ARG cur, want;
    int ret;

    WC_CAS_WITH_RETRY_BEGIN_INIT_CUR(&rng->poolHead, cur, ret) {
        want = WC_RNG_POOL_PACK(WC_RNG_POOL_POS(cur),
                                WC_RNG_POOL_EPOCH(cur) + 1U);
        WC_CAS_WITH_RETRY_LOOP_FOREVER(wolfSSL_Atomic_Uint_CompareExchange,
                                      &rng->poolHead, cur, want, ret);
    } WC_CAS_WITH_RETRY_END;

    return ret;
}

int wc_RNG_Pool_Alloc(WC_RNG* rng, word32 size)
{
    if ((rng == NULL) || (size < 2) || (size > 32767U))
        return BAD_FUNC_ARG; /* halves are word16; current in [0, size] */
    if (rng->pool != NULL)
        return ALREADY_E;

    rng->pool = (byte*)XMALLOC(size, rng->heap, DYNAMIC_TYPE_RNG);
    if (rng->pool == NULL)
        return MEMORY_E;
    rng->poolSize = (word16)size;
    wolfSSL_Atomic_Uint_Init(&rng->poolHead, 0);
    wolfSSL_Atomic_Uint_Init(&rng->poolTail, 0);

    return 0;
}

int wc_RNG_Pool_Collect2(WC_RNG* rng_dest, WC_RNG* rng_src, word32 n)
{
    if ((rng_dest == NULL) || (rng_src == NULL))
        return BAD_FUNC_ARG;
    if (rng_dest->pool == NULL)
        return BAD_STATE_E;

#ifdef WC_RNG_HAVE_RBGC
    /* Pool data is served directly as DRBG output, via wc_RNG_Pool_Extract().
     * To preserve the destination's provenance guarantee (SP 800-90C
     * sect. 7.3.1 item 16, no output to a predecessor), the generator stratum
     * must not be deeper than the destination stratum.  Contrast with stir data
     * (wc_RNG_DRBG_ReseedRBGC_local() uncredited path), which has and imparts
     * no provenance. */
    if (rng_src->RBGCStratum > rng_dest->RBGCStratum)
        return BAD_FUNC_ARG;
#endif

    if (n == 0)
        return 0;

    /* Note, a second writer can read the same head, generate into the same
     * span, then lose the publication CAS, having already overwritten part of
     * the winner's published bytes.  This is benign -- every byte in the span
     * is output of compatible provenance from one generate or the other, and
     * the loser just returns BUSY_E, while no invalidation is lost either way.
     *
     * If interspersal of bytes from multiple producers is undesirable, the
     * caller can simply arrange not to have multiple concurrent producxers --
     * this is the arrangement in the wolfSSL kernel module, for example, which
     * has a single daemon (wc_linuxkm_entropy_daemon()) that is the sole pool
     * collector.
     */
    {
        WC_ATOMIC_UINT_ARG snap;
        word32 head, epoch, tail, free_sz, m, done = 0;
        int ret;

        WC_ATOMIC_UINT_ARG tw;

        snap = WOLFSSL_ATOMIC_LOAD(rng_dest->poolHead);
        head = WC_RNG_POOL_POS(snap);
        epoch = WC_RNG_POOL_EPOCH(snap);
        tw = WOLFSSL_ATOMIC_LOAD(rng_dest->poolTail);

        if (WC_RNG_POOL_EPOCH(tw) != epoch) {
            /* A purge landed and the reader has not yet acknowledged it.  Its
             * resync discards everything published before the purge -- which
             * would include anything we published now -- so there is no useful
             * work here until a read happens.  Reporting NOT_READY_E rather
             * than success also keeps a collector that polls fullness from
             * spinning: wc_RNG_Pool_Current() reports empty across this
             * window, while tail still describes the retired span, so a
             * free-span computation from it would say full.  Those two
             * disagree only here, and only until the reader resyncs. */
            return NOT_READY_E;
        }

        tail = WC_RNG_POOL_POS(tw);

        free_sz = (word32)rng_dest->poolSize
                  - PoolUsed(head, tail, (word32)rng_dest->poolSize);
        if (free_sz == 0)
            return 0; /* full: success no-op */
        m = (free_sz > n) ? n : free_sz;

        /* generate directly into the unpublished span (up to two contiguous
         * segments), then publish the whole of it with one CAS. */
        while (done < m) {
            word32 at =
                PoolAt(PoolAdvance(head, done, (word32)rng_dest->poolSize),
                       (word32)rng_dest->poolSize);
            word32 chunk = (word32)rng_dest->poolSize - at;
            if (chunk > m - done)
                chunk = m - done;
            ret = wc_RNG_GenerateBlock(rng_src, rng_dest->pool + at, chunk);
            if (ret != 0) {
                /* Abandon in place.  The written bytes lie beyond head and
                 * are therefore unpublished -- benign in-boundary content
                 * awaiting overwrite.  Not burned: the reader's burn span and
                 * ours are disjoint, and zeroing here would be
                 * indistinguishable from published zeros to the next writer. */
                return ret;
            }
            done += chunk;
        }

        if (wolfSSL_Atomic_Uint_CompareExchange(
                &rng_dest->poolHead, &snap,
                WC_RNG_POOL_PACK(
                    PoolAdvance(head, m, (word32)rng_dest->poolSize), epoch)))
        {
            return 0;
        }
        else {
            /* Either we're competing with another writer, or the epoch changed
             * (invalidation).  In either case, we return BUSY_E.
             */
            return BUSY_E;
        }
    }
}

int wc_RNG_Pool_Collect(WC_RNG* rng, word32 n)
{
    return wc_RNG_Pool_Collect2(rng, rng, n);
}

int wc_RNG_Pool_Extract(WC_RNG* rng, byte* out, word32* n)
{
    WC_ATOMIC_UINT_ARG w1, w2, tw;
    word32 head, epoch, tail, avail, m, done = 0;

    if ((rng == NULL) || (out == NULL) || (n == NULL))
        return BAD_FUNC_ARG;
    {
        int lock_ret = rng_lock_required_check(rng);
        if (lock_ret != 0)
            return lock_ret;
    }
    if (rng->pool == NULL)
        return BAD_STATE_E;

#if defined(HAVE_GETPID) && !defined(WOLFSSL_NO_GETPID)
    {
        int ret = rng_pid_change_check(rng);
        if (ret != 0)
            return ret;
    }
#endif

    /* Fail closed: no serving output on behalf of an out-of-service DRBG, and
     * its pooled output is unusable material at rest.  A writer mid-fill sees
     * the epoch move and abandons rather than publishing. */
    if (wc_RNG_DRBG_Present(rng) && (rng->status != DRBG_OK)) {
        int ret = PoolPurge(rng);
        if (ret != 0)
            return ret;
        /* Reader-owned fail-closed wipe and resync of whatever was
         * pending. */
        tw = WOLFSSL_ATOMIC_LOAD(rng->poolTail);
        w1 = WOLFSSL_ATOMIC_LOAD(rng->poolHead);
        PoolWipeRetired(rng, WC_RNG_POOL_POS(tw), WC_RNG_POOL_POS(w1));
        WOLFSSL_ATOMIC_STORE(rng->poolTail,
                             WC_RNG_POOL_PACK(WC_RNG_POOL_POS(w1),
                                              WC_RNG_POOL_EPOCH(w1)));
        return RNG_FAILURE_E;
    }

    tw = WOLFSSL_ATOMIC_LOAD(rng->poolTail);
    w1 = WOLFSSL_ATOMIC_LOAD(rng->poolHead);
    head = WC_RNG_POOL_POS(w1);
    epoch = WC_RNG_POOL_EPOCH(w1);

    if (WC_RNG_POOL_EPOCH(tw) != epoch) {
        /* A purge landed since our last visit.  Everything published before
         * it is retired: resynchronize to head and report empty.  Anything
         * the writer publishes after this point is post-event and stands. */
        PoolWipeRetired(rng, WC_RNG_POOL_POS(tw), head);
        WOLFSSL_ATOMIC_STORE(rng->poolTail, WC_RNG_POOL_PACK(head, epoch));
#ifdef WC_RNG_DEBUG_STATS
        rng->_stats_pool_bytes_missed += *n;
#endif
        return NOT_READY_E;
    }

    tail = WC_RNG_POOL_POS(tw);
    avail = PoolUsed(head, tail, (word32)rng->poolSize);
    if (avail == 0) {
#ifdef WC_RNG_DEBUG_STATS
        rng->_stats_pool_bytes_missed += *n;
#endif
        return NOT_READY_E;
    }
    m = (avail > *n) ? *n : avail;

    while (done < m) {
        word32 at = PoolAt(PoolAdvance(tail, done, (word32)rng->poolSize),
                           (word32)rng->poolSize);
        word32 chunk = (word32)rng->poolSize - at;
        if (chunk > m - done)
            chunk = m - done;
        XMEMCPY(out + done, rng->pool + at, chunk);
        /* burn on the way out the door, before the span is republished.
         * [tail, tail+m) and the writer's [head, head+m') are disjoint by
         * construction, so this can never erase published bytes. */
        ForceZero(rng->pool + at, chunk);
        done += chunk;
    }

    /* The linearization point.  Both loads read head and epoch as one word,
     * so a purge anywhere in our window is caught here -- epoch moves and
     * never moves back.  Our bytes then predate the event and must not be
     * served, so discard the whole pre-event span rather than advancing. */
    w2 = WOLFSSL_ATOMIC_LOAD(rng->poolHead);
    if (WC_RNG_POOL_EPOCH(w2) != epoch) {
        /* We own [tail, old head) exclusively; the purged span is wiped
         * before it is skipped. */
        PoolWipeRetired(rng, tail, head);
        WOLFSSL_ATOMIC_STORE(rng->poolTail,
                             WC_RNG_POOL_PACK(WC_RNG_POOL_POS(w2),
                                              WC_RNG_POOL_EPOCH(w2)));
#ifdef WC_RNG_DEBUG_STATS
        rng->_stats_pool_bytes_missed += *n;
#endif
        return BUSY_E;
    }

    /* Sole writer of poolTail: a plain store, no CAS on the reader path. */
    WOLFSSL_ATOMIC_STORE(rng->poolTail,
                         WC_RNG_POOL_PACK(
                             PoolAdvance(tail, m, (word32)rng->poolSize),
                             epoch));

#ifdef WC_RNG_DEBUG_STATS
    rng->_stats_pool_bytes_produced += m;
    rng->_stats_pool_bytes_missed += *n - m; /* shortfall on partial serve */
#endif
    *n = m;

    return 0;
}

int wc_RNG_Pool_Current(WC_RNG* rng, word32* n)
{
    if ((rng == NULL) || (n == NULL))
        return BAD_FUNC_ARG;
    if (rng->pool != NULL) {
        WC_ATOMIC_UINT_ARG w = WOLFSSL_ATOMIC_LOAD(rng->poolHead);
        WC_ATOMIC_UINT_ARG tw = WOLFSSL_ATOMIC_LOAD(rng->poolTail);
        /* a purge not yet observed by the reader retires everything
         * published before it: report empty. */
        *n = (WC_RNG_POOL_EPOCH(tw) != WC_RNG_POOL_EPOCH(w)) ? 0 :
             PoolUsed(WC_RNG_POOL_POS(w), WC_RNG_POOL_POS(tw),
                      (word32)rng->poolSize);
    }
    else {
        *n = 0;
    }
    return 0;
}
#endif /* WC_RNG_HAVE_POOL */

#ifdef WC_RNG_HAVE_RBGC

/* Unified mechanics for the four wc_InitRng*RBGC() APIs: instantiate a child
 * DRBG subordinate to parent in an SP 800-90C RBG chain, drawing its seed
 * material from parent's generate function in place of the module's seed
 * source; every other aspect of instantiation -- seed byte accounting, nonce
 * handling, failure disposition -- is _InitRng()'s, identically to
 * wc_InitRngNonce_ex() with the omission of health testing, which is
 * superfluous when a healthy DRBG generates the seed data.
 *
 * SP 800-90C accounting: the child's claimable security strength is capped by
 * the parent's, and the child has no formal prediction resistance.  The child's
 * own reseeds default to the module's seed source (the reseed-interval
 * backstop, wc_RNG_DRBG_Reseed_Now()); wc_RNG_DRBG_ReseedRBGC() reseeds it from
 * a supplied root instead.  In configurations with no DRBG (RDRAND et al.), the
 * child comes up as _InitRng() dictates for such configurations and the parent
 * is not consulted.
 *
 * Exactly one of new_child_stack (caller-provided WC_RNG, uninitialized) and
 * new_child_heap (callee-allocated from parent's heap, to be released with
 * wc_rng_free()) must be non-NULL.  The caller must hold exclusive access
 * to parent for the duration of the call, as for all WC_RNG operations; the
 * spawn debits parent's reseed counter by one generate.
 */
static WARN_UNUSED_RESULT int SpawnRngRBGC(
                        WC_RNG* new_child_stack, WC_RNG** new_child_heap,
                        WC_RNG* parent, const byte* nonce, word32 nonceSz,
                        const byte *perso, word32 persoSz,
                        word32 flags)
{
    WC_RNG* child = new_child_stack;
    int ret;

    if (parent == NULL)
        return BAD_FUNC_ARG;

    if ((new_child_stack == NULL) == (new_child_heap == NULL))
        return BAD_FUNC_ARG;

    if (new_child_stack == parent)
        return BAD_FUNC_ARG;

    if ((nonce == NULL) && (nonceSz > 0))
        return BAD_FUNC_ARG;

    if (new_child_heap != NULL) {
        *new_child_heap = (WC_RNG*)XMALLOC(sizeof(WC_RNG), parent->heap,
        DYNAMIC_TYPE_RNG);
        if (*new_child_heap == NULL)
            return MEMORY_E;
        child = *new_child_heap;
    }

    ret = _InitRng(child, nonce, nonceSz, perso, persoSz, parent->heap,
    #if defined(WOLF_CRYPTO_CB)
                   parent->devId,
    #else
                   INVALID_DEVID,
    #endif
                   parent, flags);

    if (new_child_heap != NULL) {
        if (ret != 0) {
            XFREE(child, parent->heap, DYNAMIC_TYPE_RNG);
            *new_child_heap = child = NULL;
        }
    }

    return ret;
}

int wc_InitRngRBGC(WC_RNG* child, WC_RNG* parent, word32 flags)
{
    return SpawnRngRBGC(child, NULL, parent, NULL, 0, NULL, 0, flags);
}

int wc_InitRngNonceRBGC(WC_RNG* child, WC_RNG* parent, const byte* nonce,
                        word32 nonceSz, const byte *perso, word32 persoSz,
                        word32 flags)
{
    return SpawnRngRBGC(child, NULL, parent, nonce, nonceSz, perso, persoSz,
                        flags);
}

#ifndef WC_NO_CONSTRUCTORS
int wc_InitRngRBGC_New(WC_RNG** child, WC_RNG* parent, word32 flags)
{
    return SpawnRngRBGC(NULL, child, parent, NULL, 0, NULL, 0, flags);
}

int wc_InitRngNonceRBGC_New(WC_RNG** child, WC_RNG* parent, const byte* nonce,
                            word32 nonceSz, const byte *perso, word32 persoSz,
                            word32 flags)
{
    return SpawnRngRBGC(NULL, child, parent, nonce, nonceSz, perso, persoSz,
                        flags);
}
#endif /* !WC_NO_CONSTRUCTORS */

/* Immediately reseed rng from root's generate output -- the reseed counterpart
 * of the wc_InitRng*RBGC() spawn.  The reseed counter is reset iff the reseed
 * succeeds and credited.  The nonce, if any, rides the same reseed derivation
 * as (uncredited) additional input.  The caller must hold exclusive access to
 * BOTH rng and root.  On credited success, rng is (or remains) a chain RNG:
 * its current seed period is chain-backed, so RBGCStratum is set, and it is not
 * usable as a reseed root.
 *
 * By default, consistent with SP 800-90C 7.1.2.2, reseed by an RBGC root is
 * allowed, provided its stratum is less than the child's stratum (no stratum
 * downgrade allowed, no cycles possible); build-time option
 * WC_RNG_NO_RBGC_RESEED restricts credited reseeds to primary-seeded roots.
 *
 * Uncredited reseeds by wc_RNG_DRBG_ReseedRBGC_local() are unconditionally
 * permitted (these are just stirs).
 */
static WARN_UNUSED_RESULT int wc_RNG_DRBG_ReseedRBGC_local(
                                        WC_RNG* rng, WC_RNG* root,
                                        const byte* nonce, word32 nonceSz,
                                        int credited)
{
#ifdef WOLFSSL_SMALL_STACK_CACHE
    byte *seed;
#else
    byte seed[SEED_SZ];
#endif
    int ret;

    if ((rng == NULL) || (root == NULL) || (rng == root) ||
        ((nonce == NULL) && (nonceSz > 0)))
    {
        return BAD_FUNC_ARG;
    }

    ret = rng_lock_required_check(rng);
    if (ret != 0)
        return ret;

    ret = rng_lock_required_check(root);
    if (ret != 0)
        return ret;

    if (credited) {
        if (root->RBGCStratum >= WC_MAX_SINT_OF(int))
            return SEQ_OVERFLOW_E;
        else if (root->RBGCStratum == WC_RNG_RBGC_USER_SEED_STRATUM - 1)
            return SEQ_OVERFLOW_E;
    }
    /* else the RBGC strata are irrelevant -- stir data has no implication of
     * provenance, and can legitimately be wall clock time or even strings of
     * zeros. */

#ifdef WOLFSSL_SMALL_STACK_CACHE
    seed = rng->newSeed_buf;
#endif

    if (credited && (root->RBGCStratum > 0)
#ifndef WC_RNG_NO_RBGC_RESEED
        && (root->RBGCStratum >= rng->RBGCStratum)
#else
    /* Credited reseed from root only, by policy. */
#endif
        )
    {
        return BAD_FUNC_ARG;
    }

    if (rng->status != DRBG_OK)
        return RNG_FAILURE_E;

    if (! wc_RNG_DRBG_Present(rng)) {
        return 0;
    }

    ret = wc_RNG_GenerateBlock(root, seed, SEED_SZ);
    if (ret == 0) {
        if (credited) {
            ret = Hash_DRBG_Reseed(rng, seed, SEED_SZ, nonce, nonceSz,
                                   0 /* in_bracketed_consume */);
            if (ret == 0) {
                rng->RBGCStratum = root->RBGCStratum + 1;
    #ifdef WC_RNG_DEBUG_STATS
                ++rng->_stats_RBGC_reseeds;
    #endif
            }
        }
        else {
            ret = wc_RNG_DRBG_Stir_Nonce_local(rng, seed, SEED_SZ, nonce,
                                                      nonceSz);
        }
    }
    ForceZero(seed, SEED_SZ);

    return ret;
}

int wc_RNG_DRBG_ReseedRBGC(WC_RNG* rng, WC_RNG* root, const byte* nonce,
                           word32 nonceSz)
{
    return wc_RNG_DRBG_ReseedRBGC_local(rng, root, nonce, nonceSz, 1);
}

int wc_RNG_DRBG_StirRBGC(WC_RNG* rng, WC_RNG* root,
                                      const byte* nonce, word32 nonceSz)
{
    return wc_RNG_DRBG_ReseedRBGC_local(rng, root, nonce, nonceSz, 0);
}

#endif /* WC_RNG_HAVE_RBGC */

#if defined(HAVE_HASHDRBG) && !defined(CUSTOM_RAND_GENERATE_BLOCK)

static WARN_UNUSED_RESULT int PollAndReSeed(WC_RNG* rng, const byte* additional,
                         word32 additionalSz)
{
    int ret   = WC_NO_ERR_TRACE(DRBG_NEED_RESEED);
    int devId = INVALID_DEVID;
#if defined(WOLFSSL_ASYNC_CRYPT) || defined(WOLF_CRYPTO_CB)
    devId = rng->devId;
#endif
    ret = wc_RNG_HealthTestLocal(rng, 1, rng->heap, devId);
    if (ret == 0) {
    #if defined(WOLFSSL_SMALL_STACK_CACHE)
        byte* newSeed = rng->newSeed_buf;
        ret = DRBG_SUCCESS;
    #elif defined(WOLFSSL_SMALL_STACK)
        byte* newSeed = (byte*)XMALLOC(SEED_SZ + SEED_BLOCK_SZ, rng->heap,
            DYNAMIC_TYPE_SEED);
        ret = (newSeed == NULL) ? MEMORY_E : DRBG_SUCCESS;
    #else
        byte newSeed[SEED_SZ + SEED_BLOCK_SZ];
        ret = DRBG_SUCCESS;
    #endif
        if (ret == DRBG_SUCCESS) {
        #ifdef WC_RNG_SEED_CB
            if (seedCb == NULL) {
                ret = DRBG_NO_SEED_CB;
            }
            else {
                ret = seedCb(&rng->seed, newSeed, SEED_SZ + SEED_BLOCK_SZ);
                if (ret != 0) {
    #ifdef WC_VERBOSE_RNG
                    WOLFSSL_DEBUG_PRINTF("ERROR: seedCb() in PollAndReSeed() "
                                         "failed with err %d", ret);
    #endif
                    if (ret > 0) /* app callback: keep negative codes */
                        ret = DRBG_FAILURE;
                }
            }
        #else
            ret = wc_GenerateSeed(&rng->seed, newSeed,
                              SEED_SZ + SEED_BLOCK_SZ);
            if (ret != 0) {
    #ifdef WC_RNG_DEBUG_STATS
                ++rng->_stats_seed_failures;
    #endif
    #ifdef WC_VERBOSE_RNG
                WOLFSSL_DEBUG_PRINTF(
                    "ERROR: wc_GenerateSeed() in PollAndReSeed() failed with "
                    "err %d", ret);
    #endif
            }
        #endif
        }
        if (ret == DRBG_SUCCESS) {
            ret = wc_RNG_TestSeed(newSeed, SEED_SZ + SEED_BLOCK_SZ);
    #ifdef WC_RNG_DEBUG_STATS
            if (ret != DRBG_SUCCESS)
                ++rng->_stats_seed_failures;
    #endif
    #ifdef WC_VERBOSE_RNG
            if (ret != DRBG_SUCCESS)
                WOLFSSL_DEBUG_PRINTF(
                    "ERROR: wc_RNG_TestSeed() in PollAndReSeed() returned "
                    "err %d.", ret);
    #endif
        }
        if (ret == DRBG_SUCCESS) {
            ret = Hash_DRBG_Reseed(rng, newSeed + SEED_BLOCK_SZ, SEED_SZ,
                                   additional, additionalSz,
                                   0 /* in_bracketed_consume */);

        #ifdef WC_RNG_HAVE_RBGC
            if (ret == 0)
                rng->RBGCStratum = 0;
        #endif
        }
    #if defined(WOLFSSL_SMALL_STACK) && !defined(WOLFSSL_SMALL_STACK_CACHE)
        if (newSeed != NULL) {
            ForceZero(newSeed, SEED_SZ + SEED_BLOCK_SZ);
        }
        XFREE(newSeed, rng->heap, DYNAMIC_TYPE_SEED);
    #else
        /* newSeed is a byte[] in the plain build but a byte* in the
         * SMALL_STACK_CACHE build, so use the explicit buffer length (not
         * sizeof) to zero the whole reseed entropy buffer in both cases. */
    #ifdef WOLFSSL_CHECK_MEM_ZERO
        wc_MemZero_Add("PollAndReSeed newSeed", newSeed,
            SEED_SZ + SEED_BLOCK_SZ);
    #endif
        ForceZero(newSeed, SEED_SZ + SEED_BLOCK_SZ);
    #ifdef WOLFSSL_CHECK_MEM_ZERO
        wc_MemZero_Check(newSeed, SEED_SZ + SEED_BLOCK_SZ);
    #endif
    #endif
    }
    /* else pass back the failure code from wc_RNG_HealthTestLocal():
     * DRBG_CONT_FAILURE from the KAT means ConstantCompare mismatch, i.e.  a
     * machinery failure; infrastructure codes (MEMORY_E, or DRBG_FAILURE as the
     * internal ops' catch-all) are distinct and retryable.
     */

    return ret;
}

/* Immediately reseed rng from the module's built-in or previously registered
 * seed source, exactly as the WC_RESEED_INTERVAL backstop does during a
 * generate operation: the gathered seed is health-tested and applied by the
 * module's own reseed function, and the reseed counter is reset iff the
 * reseed succeeds.  If nonceSz > 0, nonce is incorporated into the same
 * reseed derivation as (uncredited) additional input, with the semantics of
 * wc_RNG_DRBG_Stir(), in a single state transition.  On failure
 * the reseed counter is not reset and rng->status reflects the failure
 * exactly as a generate-time reseed failure would.  The caller must hold
 * exclusive access to rng, as for all WC_RNG operations. */
int wc_RNG_DRBG_Reseed_Now(WC_RNG* rng, const byte* nonce, word32 nonceSz)
{
    int ret;

    if (rng == NULL)
        return BAD_FUNC_ARG;
    if ((nonce == NULL) && (nonceSz > 0))
        return BAD_FUNC_ARG;
    ret = rng_lock_required_check(rng);
    if (ret != 0)
        return ret;

    /* Not reached from the generate path, so it takes the lock here.  The
     * checks below read state a generate writes under it, so they follow. */
    ret = RngAutoLockEnter(rng);
    if (ret != 0)
        return ret;

    /* Mirror wc_RNG_GenerateBlock(): only an in-service DRBG may reseed. */
    if (rng->status != DRBG_OK) {
        ret = RNG_FAILURE_E;
        goto out;
    }

    if (! wc_RNG_DRBG_Present(rng)) {
        /* No DRBG instantiated -- nothing to reseed (RDRAND et al.). */
        ret = 0;
        goto out;
    }

    ret = PollAndReSeed(rng, nonce, nonceSz);

    if (ret == DRBG_SUCCESS) {
        ret = 0;
    }
    else if (ret == WC_NO_ERR_TRACE(DRBG_CONT_FAILURE)) {
        rng->status = DRBG_CONT_FAILED;
        ret = DRBG_CONT_FIPS_E;
    }
    else {
        wc_drbg_reseed_ctr_t ctr = WC_RESEED_INTERVAL;
        (void)wc_RNG_DRBG_GetReseedCtr(rng, &ctr);
        if (ctr >= WC_RESEED_INTERVAL) {
            /* The instance is out of generate runway -- condemn now, matching
             * wc_RNG_GenerateBlock()'s behavior for mandatory reseeds. */
            rng->status = DRBG_FAILED;
        }
        if (ret > 0) {
            /* Translate protocol-domain codes at the API boundary. */
            ret = (ctr >= WC_RESEED_INTERVAL) ? RNG_FAILURE_E : NOT_READY_E;
        }
        /* else distinct wolfCrypt codes (ENTROPY_RT_E/APT_E, MEMORY_E, etc.)
         * pass through verbatim -- source health is never masked. */
    }

    out:

    RngAutoLockExit(rng);
    return ret;
}

#ifdef WC_RNG_HAVE_NEXT_SEED

    /* Banked-next-seed services.  _NextSeedGenerate() banks up to n more
     * bytes from the module's seed source (clamped to the space remaining;
     * ALREADY_E when the bank is ready or being consumed), health-testing
     * and publishing the bank when it completes (NOT_READY_E when the health
     * test could not run and the call should simply be retried); a
     * scheduling daemon may call it without owning the instance.
     * _NextSeedCurrent() reports the raw aperture value (racy snapshot).
     * _NextSeedNow() claims a ready bank and performs a source-free
     * credited reseed with it -- safe in atomic context -- or returns
     * NOT_READY_E when no bank is ready; _NextSeedNow_Nonce() is the same
     * with a nonce as uncredited additional input.  All report
     * MISSING_RNG_E for an instance with no DRBG (RDRAND et al.).  The
     * caller must own the instance for _NextSeedNow[_Nonce](). */

/* Banked-next-seed protocol.
 *
 * Entropy is gathered incrementally, in-boundary, from the
 * module's seed source by wc_RNG_DRBG_NextSeedGenerate(), and consumed
 * (source-free, atomic-context-safe) by wc_RNG_DRBG_NextSeedNow().
 * nextSeedLen is the hand-off aperture: values in [0, bank length)
 * count banked bytes (filling); WC_DRBG_NEXT_SEED_READY marks a complete,
 * health-tested bank; WC_DRBG_NEXT_SEED_CONSUMING marks exclusive ownership by a
 * consumer.
 *
 * DRBG_internal.nextSeedLen (and the DRBG_SHA512_internal analog) is a
 * wolfSSL_Atomic_Int with C-native atomic semantics (release stores, acquire
 * loads, sequentially consistent RMWs):
 *
 * The single scheduling daemon (one writer per instance, by contract) advances
 * the fill with the AddFetch in wc_RNG_DRBG_NextSeedGenerate() and publishes by
 * storing _READY; a consumer claims with a CAS from _READY to _CONSUMING,
 * consumes, zeroizes, and releases to _EMPTY.  Ownership-taking transitions are
 * atomic RMWs and releases are atomic stores with release semantics, so the
 * hand-off is ordered on all supported targets, and the daemon never touches
 * any other DRBG state.  Gathering draws from the configured / installed
 * entropy source directly, never from rng->seed, so the daemon also does not
 * race an owner's own source reseed. */

/* Locate the aperture members for rng's live DRBG.  Returns nonzero when no
 * DRBG is instantiated (RDRAND et al.). */
static WARN_UNUSED_RESULT WC_INLINE int NextSeedPtrs(WC_RNG* rng,
                                  byte** seed, word32 *nextSeedSz,
                                  wolfSSL_Atomic_Int** len,
                                  int **nextSeedRBGCStratum)
{
#ifndef NO_SHA256
    if ((rng->drbgType == WC_DRBG_SHA256) && (rng->drbg != NULL)) {
        *seed = ((DRBG_internal*)rng->drbg)->nextSeed;
        *nextSeedSz = (word32)sizeof(((DRBG_internal*)rng->drbg)->nextSeed);
        *len  = &((DRBG_internal*)rng->drbg)->nextSeedLen;
        if (nextSeedRBGCStratum) {
        #ifdef WC_RNG_HAVE_RBGC
            *nextSeedRBGCStratum =
                &((DRBG_internal*)rng->drbg)->nextSeedRBGCStratum;
        #else
            *nextSeedRBGCStratum = NULL;
        #endif
        }
        return 0;
    }
#endif
#ifdef WOLFSSL_DRBG_SHA512
    if ((rng->drbgType == WC_DRBG_SHA512) && (rng->drbg512 != NULL)) {
        *seed = ((DRBG_SHA512_internal*)rng->drbg512)->nextSeed;
        *nextSeedSz =
            (word32)sizeof(((DRBG_SHA512_internal*)rng->drbg512)->nextSeed);
        *len  = &((DRBG_SHA512_internal*)rng->drbg512)->nextSeedLen;
        if (nextSeedRBGCStratum) {
        #ifdef WC_RNG_HAVE_RBGC
            *nextSeedRBGCStratum =
                &((DRBG_SHA512_internal*)rng->drbg512)->nextSeedRBGCStratum;
        #else
            *nextSeedRBGCStratum = NULL;
        #endif
        }
        return 0;
    }
#endif
    return MISSING_RNG_E;
}

/* Bank up to n more bytes of seed material from a supplied root RNG into
 * rng's next-seed bank.  Callable without owning the instance (the scheduling
 * daemon's entry point); deliberately independent of rng->status so that
 * banking can proceed for any instantiated DRBG.  n is clamped to the space
 * remaining; a ready or consuming bank is signaled with ALREADY_E.  On
 * completing the bank, the material is health-tested (wc_RNG_TestSeed()) and
 * published; a failed test consumes the material (use-once) and returns the
 * test's error, leaving an empty bank for the next cycle.  A gather failure
 * leaves the partial bank intact for retry. */
static WARN_UNUSED_RESULT int wc_RNG_DRBG_NextSeedGenerate_local(
                                              WC_RNG* rng, WC_RNG* root,
                                              word32 n)
{
    int claim_ret;
    byte* seed = NULL;
    wolfSSL_Atomic_Int* lenp = NULL;
    int* nextSeedRBGCStratum_p = NULL;
    WC_ATOMIC_INT_ARG cur;
    word32 nextSeedSz = 0;
    int ret;

    if ((rng == NULL) || (n == 0) || (rng == root))
        return BAD_FUNC_ARG;

    /* Note, rng need not be locked -- that's the whole point of the
     * banked-next-seed aperture protocol.  However, the two aperture lanes
     * (WC_RNG.nextStir and DRBG_internal.nextSeed) earn that differently.  The
     * stir lane is WC_RNG-resident: uncredited material carries no
     * adjudication, so it survives DRBG teardown/reinit harmlessly, and
     * depositors (wc_RNG_DRBG_NextStirStore()) are blind by design -- they
     * never dereference rng->drbg.  This (credited) lane is DRBG-resident: a
     * banked seed carries health-test and stratum adjudication that must die
     * with the generation it was banked for, so it must not outlive rng->drbg
     * -- and therefore fills here race wc_FreeRng().  In-bank,
     * bank->inst_op_gate mutually excludes production
     * (wc_rng_bank_next_seed_generate_local()) from instance free/reinit
     * (wc_rng_bank_inst_reinit()); outside banks, the instance is caller-owned
     * and the caller is the only party doing either. */

    if (root) {
        ret = rng_lock_required_check(root);
        if (ret != 0)
            return ret;
#ifdef WC_RNG_HAVE_RBGC
        if ((root->RBGCStratum > 0)
    #ifndef WC_RNG_NO_RBGC_RESEED
            && (root->RBGCStratum >= rng->RBGCStratum)
    #else
            /* Credited reseed from root only, by policy. */
    #endif
            )
        {
            return BAD_FUNC_ARG;
        }
        if (root->RBGCStratum >= WC_MAX_SINT_OF(int))
            return SEQ_OVERFLOW_E;
        else if (root->RBGCStratum == WC_RNG_RBGC_USER_SEED_STRATUM - 1)
            return SEQ_OVERFLOW_E;
#else
        return NOT_COMPILED_IN;
#endif
    }

    ret = NextSeedPtrs(rng, &seed, &nextSeedSz, &lenp,
                       &nextSeedRBGCStratum_p);
    if (ret != 0) {
        /* No DRBG instantiated -- nothing to bank (RDRAND et al.). */
        return ret;
    }

    cur = WOLFSSL_ATOMIC_LOAD(*lenp);
    {
        /* Producer claim: exactly one banker may fill or publish at a
         * time.  Concurrent fills would be tolerable as BYTES (a torn
         * mix is still entropy) but poisonous as CLAIMS: interleaved
         * primary/RBGC production could publish material under the
         * wrong stratum or health-test disposition.  The claim makes
         * produce-side exclusivity a CAS, matching the consume side's
         * READY -> CONSUMING claim.  This lane only: the uncredited
         * accumulator above stays multi-writer by design. */
        WC_CAS_WITH_RETRY_BEGIN(lenp, cur, claim_ret) {
            if ((cur == WC_DRBG_NEXT_SEED_PRODUCING) ||
                (cur == WC_DRBG_NEXT_SEED_PURGED))
            {
                /* A producer is in flight (or unwinding a purge):
                 * retryable on a later banking cycle.  Traced: the
                 * competing producer -- typically the entropy daemon
                 * -- is the diagnosis a surprised caller needs. */
                return BUSY_E;
            }
            if (cur < 0) {
                /* Ready or consuming -- nothing to do. */
                return WC_NO_ERR_TRACE(ALREADY_E); /* not an error */
            }
            WC_CAS_WITH_RETRY_LOOP_FOREVER(wolfSSL_Atomic_Int_CompareExchange,
                                          lenp, cur,
                                          WC_DRBG_NEXT_SEED_PRODUCING,
                                          claim_ret);
        } WC_CAS_WITH_RETRY_END;
        if (claim_ret != 0) {
            /* Aborted claim (a port's retry clause): nothing claimed,
             * nothing moved.  Proceeding would fill and adjudicate an
             * unclaimed aperture -- the torn-claims disease the
             * producer mutex exists to prevent. */
            return claim_ret;
        }
        if (cur == (WC_ATOMIC_INT_ARG)nextSeedSz) {
            /* Complete but unpublished (interrupted between fill
             * completion and publication): retry the health test and
             * publication below. */
            n = 0;
        }
        /* From here to release/publication the aperture word is
         * PRODUCING; fill progress lives only in the local cur, and
         * every exit passes through NextSeedProducerRelease(). */
    }

    if (n > 0) {
#ifdef WC_RNG_HAVE_RBGC
        if (root) {
            /* If primary seed bytes were carried forward, reset now to avoid
             * wc_RNG_TestSeed() at completion.  Local only: the word is
             * held at PRODUCING. */
            if ((cur > 0) && (*nextSeedRBGCStratum_p == 0))
                cur = 0;

            if (n > nextSeedSz - (word32)cur)
                n = nextSeedSz - (word32)cur;

            ret = wc_RNG_GenerateBlock(root, seed + cur, n);
            if (ret != 0) {
                /* Partial bank preserved -- retry on a later cycle.
                 * (If a purge landed meanwhile, the release discards
                 * instead; the draw failure is the more informative
                 * code and wins over the release's BUSY_E.)
                 *
                 * Note, a failed release cannot brick the RNG and needs no
                 * disposition at the several (void) sites below: its one cause
                 * is a purge's _PURGED repaint (producers cannot claim a
                 * PRODUCING word, consumers exchange only from READY, and the
                 * purge is the sole other writer), and the BUSY arm is its own
                 * compensation -- it wipes and reopens the aperture EMPTY
                 * before returning.  Afterward the world is fully consistent:
                 * aperture empty and healthy, rng->status untouched, recovery
                 * proceeding through the event's normal channels.  BUSY_E is
                 * information, not a condition awaiting action; the caller's
                 * own error outranks it wherever one is in flight.  Cost of
                 * swallowing it: at worst one silent refill from offset
                 * zero.
                 */
                (void)NextSeedProducerRelease(lenp, seed, nextSeedSz, cur);
                return ret;
            }

            /* If RBGC seed bytes were carried forward, make sure we're
             * pessimistic about the RBGC stratum. */
            if ((cur == 0) || (*nextSeedRBGCStratum_p < root->RBGCStratum + 1))
                *nextSeedRBGCStratum_p = root->RBGCStratum + 1;
        }
        else
#endif /* WC_RNG_HAVE_RBGC */
        {
            /* wc_GenerateSeed() must be called completely independent of rng,
             * aside from the memory aperture itself.  For safety, we pass a
             * dummy OS_Seed, which will be ignored by the wc_GenerateSeed()
             * typically used in conjunction with WC_RNG_HAVE_NEXT_SEED.
             */
            struct OS_Seed os;

            /* Named-member init: layout-proof against OS_Seed growing or
             * reordering members under its several config axes. */
            XMEMSET(&os, 0, sizeof(os));
#ifndef USE_WINDOWS_API
            os.fd = -1;
#endif
#ifdef WOLF_CRYPTO_CB
            /* devId is config, not state: a callback-only seed source must
             * serve the bank the same way it serves wc_InitRng(). */
            os.devId = rng->seed.devId;
#endif

#ifdef WC_RNG_HAVE_RBGC
            /* If RBGC seed bytes were carried forward, reset now to avoid
             * intermixture and force wc_RNG_TestSeed() at completion.
             * Local only: the word is held at PRODUCING. */
            if ((cur > 0) && (*nextSeedRBGCStratum_p > 0))
                cur = 0;
#endif

            if (n > nextSeedSz - (word32)cur)
                n = nextSeedSz - (word32)cur;

            ret = wc_GenerateSeed(&os, seed + cur, n);
            if (ret != 0) {
                /* Partial bank preserved -- retry on a later cycle.
                 * (If a purge landed meanwhile, the release discards
                 * instead; the seed-gather failure is the more
                 * informative code and wins over the release's
                 * BUSY_E.) */
                (void)NextSeedProducerRelease(lenp, seed, nextSeedSz, cur);
                return ret;
            }

#ifdef WC_RNG_HAVE_RBGC
            *nextSeedRBGCStratum_p = 0;
#endif
        }

        cur += (int)n;
    }

    if (cur < (WC_ATOMIC_INT_ARG)nextSeedSz) {
        /* Partial credited fill this call: release the claim back to
         * the fill offset for a later cycle to resume.  A purge
         * meanwhile discards instead, and the release's BUSY_E
         * percolates -- returning 0 would claim banked progress the
         * purge just evaporated. */
        return NextSeedProducerRelease(lenp, seed, nextSeedSz, cur);
    }

    if (cur == (WC_ATOMIC_INT_ARG)nextSeedSz) {
#ifdef WC_RNG_HAVE_RBGC
        /* If RBGC bytes were used for the reseed, then we can skip
         * wc_RNG_TestSeed(). */
        if (*nextSeedRBGCStratum_p > 0) {
            ret = NextSeedProducerRelease(lenp, seed, nextSeedSz,
                                          WC_DRBG_NEXT_SEED_READY);
            if (ret != 0) {
                /* Purged while producing (BUSY_E): nothing banked;
                 * post-event material wanted.  Retryable. */
                return ret;
            }
            #ifdef WC_RNG_DEBUG_STATS
            ++rng->_stats_nextseedsbanked;
            #endif
            return 0;
        }
#endif
        /* Bank complete: health-test now, in advance of consumption, so
         * that wc_RNG_DRBG_NextSeedNow() is pure computation. */
        ret = wc_RNG_TestSeed(seed, nextSeedSz);
        if (ret == 0) {
            ret = NextSeedProducerRelease(lenp, seed, nextSeedSz,
                                          WC_DRBG_NEXT_SEED_READY);
            if (ret != 0) {
                /* Purged while producing (BUSY_E): nothing banked;
                 * post-event material wanted.  Retryable. */
                return ret;
            }
            #ifdef WC_RNG_DEBUG_STATS
            ++rng->_stats_nextseedsbanked;
            #endif
            return 0;
        }
        else if (ret == WC_NO_ERR_TRACE(MEMORY_E)) {
            /* wc_RNG_TestSeed() did nothing with the data -- not
             * dispositive.  Release complete-but-unpublished for a
             * later retry; a purge-discard's BUSY_E percolates (the
             * retry cause is then the purge, not the test). */
            ret = NextSeedProducerRelease(lenp, seed, nextSeedSz,
                                          (WC_ATOMIC_INT_ARG)nextSeedSz);
            if (ret != 0)
                return ret;
            return NOT_READY_E;
        }
        else if ((ret == WC_NO_ERR_TRACE(ENTROPY_RT_E)) ||
                 (ret == WC_NO_ERR_TRACE(ENTROPY_APT_E)))
        {
            /* Use-once: a failed test consumes the material. */
            #ifdef WC_RNG_DEBUG_STATS
            ++rng->_stats_seed_failures;
            #endif
            /* Use-once on a failed test is enforced by the sentinel
             * alone: an EMPTY aperture is never consumed, and the next
             * fill overwrites from offset zero.  The buffer is never
             * zeroized (house rule for the seed apertures).  Burn and
             * purge-discard converge on EMPTY; the release handles
             * both, and the health-test failure is the more
             * informative code and wins over the release's BUSY_E. */
            /* Sentinel-only by doctrine: rejection here is deterministic
             * on the bytes (RCT/APT), so every sibling lineage rejects the
             * identical material -- no copy is ever consumed anywhere. */
            (void)NextSeedProducerRelease(lenp, seed, nextSeedSz,
                                          WC_DRBG_NEXT_SEED_EMPTY);

            /* The health-test failure belongs to the depositor's seed
             * collection, not to the destination RNG.  The depositor collects
             * via wc_GenerateSeed(), banks into rng's aperture, and tests
             * before publishing; on failure the aperture is reset to _EMPTY,
             * so nothing untested is ever visible to rng.  rng is a passive
             * destination here -- it did not consume the material, and its
             * state, status and reseed schedule are untouched.  Do not mark it
             * failed.
             *
             * PollAndReSeed() looks similar and is not: there, rng is reseeding
             * itself from its own seed source, the tested material is on the
             * path into its own state, and a failure indeed means that that
             * instance's source has failed.  DRBG_FAILED is correct there and
             * wrong here.  Per-instance attribution is meaningful, not
             * arbitrary: seed sources are frequently core-local (RDSEED among
             * them), so one instance's source can fail while its siblings' are
             * healthy.
             *
             * Bigger picture: An RCT/APT failure is an entropy-source event (SP
             * 800-90B 4.4), and wc_RNG_TestSeed's cutoffs carry a designed
             * false-positive rate.  A terminal response from a thread that is
             * not the instance's owner would effectively be a remote kill
             * primitive on a tuned statistical alarm.
             */

            return ret;
        }
        else {
            /* Buggy or brokey.  Release complete-but-unpublished; the
             * material is untested but intact, and a later cycle
             * re-adjudicates.  The primary error is the more
             * informative code and wins over a purge-discard's
             * BUSY_E. */
            (void)NextSeedProducerRelease(lenp, seed, nextSeedSz,
                                          (WC_ATOMIC_INT_ARG)nextSeedSz);
            return ret;
        }
    }

    return 0;
}

#ifdef WC_RNG_HAVE_RBGC
int wc_RNG_DRBG_NextSeedGenerate_RBGC(WC_RNG* rng, WC_RNG *root, word32 n) {
    if (root == NULL)
        return BAD_FUNC_ARG;
    return wc_RNG_DRBG_NextSeedGenerate_local(rng, root, n);
}
#endif

int wc_RNG_DRBG_NextSeedGenerate(WC_RNG* rng, word32 n) {
    return wc_RNG_DRBG_NextSeedGenerate_local(rng, NULL, n);
}

/* Report the raw aperture value: a racy snapshot by design.  Values in [0, bank
 * length) count banked bytes; WC_DRBG_NEXT_SEED_READY and
 * WC_DRBG_NEXT_SEED_CONSUMING indicate a ready or in-consumption bank,
 * respectively.  With no DRBG instantiated, reports WC_DRBG_NEXT_SEED_EMPTY. */
int wc_RNG_DRBG_NextSeedCurrent(WC_RNG* rng, WC_ATOMIC_INT_ARG* n)
{
    byte* seed;
    wolfSSL_Atomic_Int* lenp;
    word32 nextSeedSz;

    if ((rng == NULL) || (n == NULL))
        return BAD_FUNC_ARG;

    if (NextSeedPtrs(rng, &seed, &nextSeedSz, &lenp, NULL) != 0) {
        *n = WC_DRBG_NEXT_SEED_EMPTY;
        return 0;
    }

    *n = *lenp;
    return 0;
}

/* Consume a ready next-seed bank in an immediate credited reseed.  The caller
 * must own the instance.  Source-free by construction -- the material was
 * gathered from the module's seed source and health-tested at bank time -- so
 * consumption is pure computation and safe in atomic context: the one credited
 * primary reseed shape with that property.  Distinct protocol results:
 * NOT_READY_E when no bank is ready (nothing consumed) or when an elective
 * redemption failed after consuming the bank (use-once); MISSING_RNG_E when
 * the instance has no DRBG (RDRAND et al.) -- both deliberately loud, so a
 * direct caller must demonstrate it understands the instance it holds.  (The
 * WC_RNG_BANK_FLAG_CONSUME_NEXT_SEED checkout arm is return-agnostic by
 * construction and needs neither.)  Use-once: the bank is consumed by the
 * attempt, success or failure.  Note that a banked reseed can never provide SP
 * 800-90 prediction resistance (the material predates the request by
 * construction); wc_RNG_DRBG_Reseed_Now() remains the live-gather shape. */
static WARN_UNUSED_RESULT int wc_RNG_DRBG_NextSeedNow_Nonce_local(
                                  WC_RNG* rng, const byte* nonce,
                                  word32 nonceSz)
{
    byte* seed;
    wolfSSL_Atomic_Int* lenp;
    word32 nextSeedSz;
    int *nextSeedRBGCStratum_p;
    WC_ATOMIC_INT_ARG expected = WC_DRBG_NEXT_SEED_READY;
    int ret;
    int devId;

    if (rng == NULL)
        return BAD_FUNC_ARG;

    if ((nonce == NULL) && (nonceSz != 0))
        return BAD_FUNC_ARG;

    ret = rng_lock_required_check(rng);
    if (ret != 0)
        return ret;

    /* Mirror wc_RNG_GenerateBlock(): only an in-service DRBG may reseed. */
    if (rng->status != DRBG_OK)
        return RNG_FAILURE_E;

#if defined(WOLFSSL_ASYNC_CRYPT) || defined(WOLF_CRYPTO_CB)
    devId = rng->devId;
#else
    devId = INVALID_DEVID;
#endif
    ret = wc_RNG_HealthTestLocal(rng, 1, rng->heap, devId);
    if (ret != 0) {
        if (ret == WC_NO_ERR_TRACE(DRBG_CONT_FAILURE)) {
            rng->status = DRBG_CONT_FAILED;
            return DRBG_CONT_FIPS_E;
        }
        if (ret > 0) /* protocol-domain catch-all: translate at the API */
            ret = RNG_FAILURE_E;
        return ret;
    }

    ret = NextSeedPtrs(rng, &seed, &nextSeedSz, &lenp, &nextSeedRBGCStratum_p);
    if (ret != 0) {
        /* No DRBG instantiated -- nothing to reseed (RDRAND et al.). */
        return ret;
    }

    if (! wolfSSL_Atomic_Int_CompareExchange(lenp, &expected,
                                             WC_DRBG_NEXT_SEED_CONSUMING))
    {
        /* No ready bank -- nothing consumed; reported distinctly. */
        return NOT_READY_E;
    }

    /* Identical byte accounting to PollAndReSeed(): the SEED_BLOCK_SZ
     * prefix was consumed by the bank-time health testing. */
    ret = Hash_DRBG_Reseed(rng, seed + SEED_BLOCK_SZ, SEED_SZ, nonce, nonceSz,
                           1 /* in_bracketed_consume */);

    /* Use-once: consumed by the attempt, success or not.  The scrub must be
     * visible before the aperture reopens. */
    ForceZero(seed, WC_DRBG_NEXT_SEED_LEN);

    /* Release by CAS -- one-shot, and its failure is information, not
     * contention: only NextSeedPurge() writes over a _CONSUMING claim, so a
     * failed release proves an invalidation event landed after this consume
     * claimed the material, i.e. the seed just fed to the reseed was banked
     * pre-event.  The reseed's own latch handling could not see that (an epoch
     * crossing shows only at the aperture's claim word, never in the lock
     * word), and if it entered invalidated and ran undisturbed it has already
     * cleared the latch -- so compensate: re-latch, and re-saturate the counter
     * (the stale credited reseed reset it, leaving the latch as sole
     * enforcement; wc_RNG_DRBG_ScheduleReseed() restores the second layer --
     * race-free here, under the exclusive lease).  Claims (stats, stratum
     * adoption) are made only behind a successful release.  Do NOT re-run
     * wc_RNG_invalidate_entropy() here: the event's purges already ran, and
     * re-purging would discard post-event material the banker may have
     * re-banked meanwhile. */
    {
        int cas_ret;
        WC_ATOMIC_INT_ARG expected_out = WC_DRBG_NEXT_SEED_CONSUMING;
        WC_CAS_WITH_RETRY_BEGIN(lenp, expected_out, cas_ret) {
            WC_CAS_WITH_RETRY_LOOP_UNTIL(wolfSSL_Atomic_Int_CompareExchange,
                                         lenp, expected_out,
                                         WC_DRBG_NEXT_SEED_EMPTY, cas_ret,
                                         NEEDS_RECOVERY_E);
        } WC_CAS_WITH_RETRY_END;
        if (cas_ret != 0) {
    #ifdef WC_RNG_HAVE_LOCK
            {
                WC_RNG_lock_arg_t cur_lock;
                int relatch_ret;
                WC_CAS_WITH_RETRY_BEGIN_INIT_CUR(&rng->lock, cur_lock,
                                                 relatch_ret) {
                    WC_CAS_WITH_RETRY_LOOP_FOREVER(
                        wolfSSL_Atomic_Uint_CompareExchange, &rng->lock,
                        cur_lock,
                        cur_lock | WC_RNG_LOCK_ENTROPY_INVALIDATED,
                        relatch_ret);
                } WC_CAS_WITH_RETRY_END;
                if (relatch_ret != 0) {
                    /* Aborted re-latch: latch down, counter scheduled.
                     * Latch-or-condemn (see wc_RNG_invalidate_entropy()):
                     * condemn. */
                    rng->status = DRBG_FAILED;
                }
            }
    #endif
            {
                int sched_ret = wc_RNG_DRBG_ScheduleReseed_local(rng);
                if ((ret == DRBG_SUCCESS) && (sched_ret != 0))
                    return sched_ret;
            }
            if (ret == DRBG_SUCCESS) {
                /* The discarded recovery is the whole story. */
                return cas_ret;
            }
            /* Else the reseed's own failure is the more informative code:
             * fall through to the standard outcome mapping.
             *
             * Note that the ordering here matters: the
             * wc_RNG_DRBG_ScheduleReseed() above has just saturated the reseed
             * counter (unless it too failed, leaving the re-upped latch as sole
             * enforcement); the failed reseed will fall through below and the
             * DRBG will be condemned by the runway gate.  This is intentional:
             * an invalidation-crossed failure is never elective, and the seed
             * just consumed was banked pre-event, so the instance has no
             * trustworthy runway for the gate's leniency to protect, and
             * lenient NOT_READY_E here would misreport a quarantined instance
             * as merely not-yet-ready. */
        }
        else {
    #ifdef WC_RNG_DEBUG_STATS
            if (ret == 0) {
        #ifdef WC_RNG_HAVE_RBGC
                if (*nextSeedRBGCStratum_p > 0)
                    ++rng->_stats_nextseedsRBGC_redeemed;
                else
        #endif
                    ++rng->_stats_nextseedsprimary_redeemed;
            }
    #endif
    #ifdef WC_RNG_HAVE_RBGC
            if (ret == 0) {
                rng->RBGCStratum = *nextSeedRBGCStratum_p;
                *nextSeedRBGCStratum_p = 0;
            }
    #endif
        }
    }

    if (ret == DRBG_SUCCESS) {
#if defined(HAVE_GETPID) && !defined(WOLFSSL_NO_GETPID)
        /* Check for PID change after consuming the banked seed. */
        ret = rng_pid_change_check(rng);
#else
        ret = 0;
#endif
    }
    else {
        wc_drbg_reseed_ctr_t ctr = WC_RESEED_INTERVAL;
        (void)wc_RNG_DRBG_GetReseedCtr(rng, &ctr);
        if (ret == WC_NO_ERR_TRACE(DRBG_CONT_FAILURE)) {
            /* Not reachable here -- retained only for uniformity with
             * wc_RNG_GenerateBlock() and wc_RNG_DRBG_Reseed_Now().  Where
             * reachable, the suspect seed was rejected before use, and the DRBG
             * state and runway are intact. */
            if (ctr >= WC_RESEED_INTERVAL) {
                /* The instance is out of generate runway -- condemn now, matching
                 * wc_RNG_GenerateBlock()'s behavior for mandatory reseeds. */
                rng->status = DRBG_CONT_FAILED;
            }
            ret = DRBG_CONT_FIPS_E;
        }
        else if (ctr >= WC_RESEED_INTERVAL) {
            /* The instance is out of generate runway -- condemn now, matching
             * wc_RNG_GenerateBlock()'s behavior for mandatory reseeds. */
            rng->status = DRBG_FAILED;
            ret = RNG_FAILURE_E;
        }
        else {
            ret = NOT_READY_E;
        }
    }

    return ret;
}

int wc_RNG_DRBG_NextSeedNow_Nonce(WC_RNG* rng, const byte* nonce,
                                  word32 nonceSz)
{
    int ret;

    if (rng == NULL)
        return BAD_FUNC_ARG;
    ret = RngAutoLockEnter(rng);
    if (ret != 0)
        return ret;
    ret = wc_RNG_DRBG_NextSeedNow_Nonce_local(rng, nonce, nonceSz);
    RngAutoLockExit(rng);
    return ret;
}

#if defined(WC_RNG_HAVE_NEXT_SEED) && defined(WC_RNG_HAVE_LOCK) && \
    defined(WC_RNG_HAVE_RBGC)
/* For the generate path, which holds the lock already.  Guarded to match
 * its one call site, which needs the lock and RBGC builds as well. */
static WARN_UNUSED_RESULT int wc_RNG_DRBG_NextSeedNow_local(WC_RNG* rng) {
    return wc_RNG_DRBG_NextSeedNow_Nonce_local(rng, NULL, 0);
}
#endif

int wc_RNG_DRBG_NextSeedNow(WC_RNG* rng) {
    return wc_RNG_DRBG_NextSeedNow_Nonce(rng, NULL, 0);
}

/* Deposit raw uncredited stir material into rng's accumulator.  Callable from
 * any context and without owning the instance: the deposit protocol
 * (read-copy-store) is multi-writer-tolerant -- every published span was
 * written by its publisher, lost updates merely drop entropy, and interleaved
 * fragments of compatible provenance are harmless.  A full accumulator
 * publishes WC_DRBG_NEXT_SEED_READY (no health test -- no claim is being made)
 * and shunts further deposits to xorbuf() until consumed. */
int wc_RNG_DRBG_NextStirStore(WC_RNG* rng, const byte *nonce, word32 nonceSz)
{
    WC_ATOMIC_INT_ARG cur;

    if ((rng == NULL) || (nonce == NULL) || (nonceSz == 0))
        return BAD_FUNC_ARG;

    /* Note, rng need not be locked -- that's the whole point of the
     * banked-next-stir aperture protocol.
     */

    cur = WOLFSSL_ATOMIC_LOAD(rng->nextStirLen);

    if ((cur >= 0) && (cur < (WC_ATOMIC_INT_ARG)sizeof(rng->nextStir))) {
        word32 fill = (word32)cur;
        word32 room = (word32)sizeof(rng->nextStir) - fill;
        word32 take = (nonceSz < room) ? nonceSz : room;

        XMEMCPY(rng->nextStir + fill, nonce, take);
        fill += take;
        if (fill == (word32)sizeof(rng->nextStir)) {
            WOLFSSL_ATOMIC_STORE(rng->nextStirLen, WC_DRBG_NEXT_SEED_READY);
            #ifdef WC_RNG_DEBUG_STATS
            ++rng->_stats_nextstirs_banked; /* racy */
            #endif
            nonce += take;
            nonceSz -= take; /* spillover falls through to the xorbuf() */
        }
        else {
            WOLFSSL_ATOMIC_STORE(rng->nextStirLen,
                                 cur + (WC_ATOMIC_INT_ARG)take);
            return 0;
        }
        if (nonceSz == 0)
            return 0;
    }

    if (nonceSz > (word32)sizeof(rng->nextStir))
        nonceSz = (word32)sizeof(rng->nextStir);
    xorbuf(rng->nextStir, nonce, nonceSz);

    return 0;
}

/* Consume a ready uncredited accumulator in an immediate uncredited
 * (stirring) reseed.  The caller must own the instance.  The credited=0
 * path holds the three no-ops by construction: the reseed counter is not
 * reset, WC_RNG_LOCK_ENTROPY_INVALIDATED is not cleared, and RBGCStratum
 * is unchanged -- a stir must never masquerade as recovery or promotion.
 * Use-once: the material is consumed (accumulation reopens) whether or not
 * the reseed succeeds.  The buffer is never zeroized (racy against
 * depositors, and zeroing is always a net entropy loss). */
static WARN_UNUSED_RESULT int wc_RNG_DRBG_NextStirNow_local(WC_RNG* rng)
{
    WC_ATOMIC_INT_ARG expected = WC_DRBG_NEXT_SEED_READY;
    wc_drbg_reseed_ctr_t reseedCtr;
    int ret;

    if (rng == NULL)
        return BAD_FUNC_ARG;

    ret = rng_lock_required_check(rng);
    if (ret != 0)
        return ret;

    /* Mirror wc_RNG_GenerateBlock(): only an in-service DRBG may reseed. */
    if (rng->status != DRBG_OK)
        return RNG_FAILURE_E;

    /* If a reseed is due, the RNG is not ready for a stir. */
    ret = wc_RNG_DRBG_GetReseedCtr(rng, &reseedCtr);
    if (ret < 0)
        return ret;
    if (reseedCtr >= WC_RESEED_INTERVAL)
        return NOT_READY_E;

    if (! wolfSSL_Atomic_Int_CompareExchange(&rng->nextStirLen, &expected,
                                             WC_DRBG_NEXT_SEED_CONSUMING))
    {
        /* Accumulator not READY. */
        if (expected < 0) {
            /* claimed by a racing consumer. */
            return BUSY_E;
        }
        else {
            /* empty or still accumulating -- nothing consumable yet. */
            return NOT_READY_E;
        }
    }

    ret = Hash_DRBG_StirGenerate(rng, rng->nextStir,
                                 (word32)sizeof(rng->nextStir));

#ifdef WC_RNG_DEBUG_STATS
    if (ret == 0)
        ++rng->_stats_nextstirs_redeemed;
#endif

    /* Always burn consumed data before releasing it, even if it's uncredited
     * noise.  Unlike the seed aperture, the stir aperture has no producer
     * claim: lease-free depositors xorbuf() into it at any time during
     * _CONSUMING, so the burn here can only discard an incoming overflow
     * fragment, after the full aperture has already been absorbed by
     * the StirGenerate() above. */
    ForceZero(rng->nextStir, (word32)sizeof(rng->nextStir));
    WOLFSSL_ATOMIC_STORE(rng->nextStirLen, WC_DRBG_NEXT_SEED_EMPTY);

    return ret;
}

int wc_RNG_DRBG_NextStirNow(WC_RNG* rng)
{
    int ret;

    if (rng == NULL)
        return BAD_FUNC_ARG;
    ret = RngAutoLockEnter(rng);
    if (ret != 0)
        return ret;
    ret = wc_RNG_DRBG_NextStirNow_local(rng);
    RngAutoLockExit(rng);
    return ret;
}

#endif /* WC_RNG_HAVE_NEXT_SEED */

#endif /* HAVE_HASHDRBG */

/* place a generated block in output */
#ifdef WC_HAVE_RNG_BANKREF
static WARN_UNUSED_RESULT int wc_local_RNG_GenerateBlock(WC_RNG* rng,
                                                         byte* output,
                                                         word32 sz)
#else
WOLFSSL_ABI
int wc_RNG_GenerateBlock(WC_RNG* rng, byte* output, word32 sz)
#endif
{
    int ret;

    if (rng == NULL || output == NULL)
        return BAD_FUNC_ARG;

    ret = rng_lock_required_check(rng);
    if (ret != 0)
        return ret;

    if (sz == 0)
        return 0;

#ifdef WOLF_CRYPTO_CB
    /* before the lock: a callback may fall back to this same instance */
    #ifndef WOLF_CRYPTO_CB_FIND
    if (rng->devId != INVALID_DEVID)
    #endif
    {
        ret = wc_CryptoCb_RandomBlock(rng, output, sz);
        if (ret != WC_NO_ERR_TRACE(CRYPTOCB_UNAVAILABLE))
            return ret;
        /* fall-through when unavailable */
    }
#endif

    /* These read a device, not this instance, so a lock protects nothing here.
     * On RDRAND hardware wc_InitRng() creates no lock at all, as tested. */
#ifdef HAVE_INTEL_RDRAND
    if (IS_INTEL_RDRAND(intel_flags))
        return wc_GenerateRand_IntelRD(NULL, output, sz);
#endif

#if defined(WOLFSSL_SILABS_SE_ACCEL) && defined(WOLFSSL_SILABS_TRNG)
    return silabs_GenerateRand(output, sz);
#endif

    ret = RngAutoLockEnter(rng);   /* held across every other backend */
    if (ret != 0)
        return ret;

#if defined(WOLFSSL_ASYNC_CRYPT)
    if (rng->asyncDev.marker == WOLFSSL_ASYNC_MARKER_RNG) {
        /* these are blocking */
    #ifdef HAVE_CAVIUM
        ret = NitroxRngGenerateBlock(rng, output, sz);
        RngAutoLockExit(rng);
        return ret;
    #elif defined(HAVE_INTEL_QA) && defined(QAT_ENABLE_RNG)
        ret = IntelQaDrbg(&rng->asyncDev, output, sz);
        RngAutoLockExit(rng);
        return ret;
    #else
        /* simulator not supported */
    #endif
    }
#endif

#ifdef CUSTOM_RAND_GENERATE_BLOCK
    XMEMSET(output, 0, sz);
    ret = (int)CUSTOM_RAND_GENERATE_BLOCK(output, sz);
    #ifdef WC_VERBOSE_RNG
    if (ret != 0)
        WOLFSSL_DEBUG_PRINTF(
            "ERROR: CUSTOM_RAND_GENERATE_BLOCK failed with err %d.", ret);
    #endif
    RngAutoLockExit(rng);   /* a no-op here today; the gate excludes this build */
#else

#ifdef HAVE_HASHDRBG
    if (sz > RNG_MAX_BLOCK_LEN) {
        RngAutoLockExit(rng);
        return BAD_FUNC_ARG;
    }

    if (rng->status != DRBG_OK) {
        RngAutoLockExit(rng);
        return RNG_FAILURE_E;
    }

#ifdef WC_RNG_DEBUG_STATS
    ++rng->_stats_total_requests;
    rng->_stats_total_bytes_requested += sz;
#endif

#if defined(HAVE_GETPID) && !defined(WOLFSSL_NO_GETPID)
    ret = rng_pid_change_check(rng);
    if (ret != 0) {
        RngAutoLockExit(rng);
        return ret;
    }
#endif

#if defined(WC_RNG_HAVE_NEXT_SEED) && defined(WC_RNG_HAVE_LOCK) && \
    defined(WC_RNG_HAVE_RBGC)
    if (rng->flags & WC_RNG_FLAG_RECOVER_AND_PROMOTE_FROM_NEXT_SEED) {
        /* externally-refreshed instance: consume a READY banked seed to
         * recover from entropy invalidation (any provenance -- the purge
         * in wc_RNG_invalidate_entropy() guarantees a READY seed is
         * post-event), or to promote a chain-backed instance to primary.
         * Consumption is a credited reseed, clearing the flag and
         * resetting the schedule; failure falls through to the ordinary
         * forced-reseed machinery. */
        int banked_stratum = wc_RNG_DRBG_GetNextSeedRBGCStratum(rng);
        if (banked_stratum >= 0) {
            if (((WOLFSSL_ATOMIC_LOAD(rng->lock) &
                  WC_RNG_LOCK_ENTROPY_INVALIDATED))
                ||
                ((rng->RBGCStratum > 0) && (banked_stratum == 0)))
            {
                ret = wc_RNG_DRBG_NextSeedNow_local(rng);
                if ((ret == WC_NO_ERR_TRACE(DRBG_CONT_FIPS_E)) ||
                    (ret == WC_NO_ERR_TRACE(RNG_FAILURE_E)))
                {
                    RngAutoLockExit(rng);
                    return ret;
                }
            }
        }
    }
#endif

#ifdef WC_RNG_HAVE_NEXT_SEED
    /* Universal opportunistic stir: a READY uncredited accumulator is
     * consumed by any generate, unconditionally -- stirs are always
     * harmless, and are invisible to the credited legs above (no counter
     * reset, no flag clear, no stratum change).  One relaxed load when
     * empty. */
    if (WOLFSSL_ATOMIC_LOAD(rng->nextStirLen) == WC_DRBG_NEXT_SEED_READY) {
        int stir_ret = wc_RNG_DRBG_NextStirNow_local(rng);
        if (stir_ret == WC_NO_ERR_TRACE(RNG_FAILURE_E)) {
            /* The DRBG broke while we were stirring it. */
            RngAutoLockExit(rng);
            return stir_ret;
        }
    }
#endif /* WC_RNG_HAVE_NEXT_SEED */

#ifdef WC_RNG_HAVE_LOCK
    if (WOLFSSL_ATOMIC_LOAD(rng->lock) & WC_RNG_LOCK_ENTROPY_INVALIDATED) {
        if (PollAndReSeed(rng, NULL, 0) != DRBG_SUCCESS) {
            rng->status = DRBG_FAILED;
            RngAutoLockExit(rng);
            return RNG_FAILURE_E;
        }
    }
#endif

#ifndef NO_SHA256
    if (rng->drbgType == WC_DRBG_SHA256) {
        ret = Hash_DRBG_Generate((DRBG_internal *)rng->drbg, output, sz,
                                 NULL, 0);
        if (ret == WC_NO_ERR_TRACE(DRBG_NEED_RESEED)) {
            ret = PollAndReSeed(rng, NULL, 0);
            if (ret != DRBG_SUCCESS) {
                if (ret == WC_NO_ERR_TRACE(DRBG_CONT_FAILURE))
                    rng->status = DRBG_CONT_FAILED;
                else
                    rng->status = DRBG_FAILED;
            }
            else {
                ret = Hash_DRBG_Generate((DRBG_internal *)rng->drbg, output,
                                         sz, NULL, 0);
            }
        }
    }
    else
#endif
#ifdef WOLFSSL_DRBG_SHA512
    if (rng->drbgType == WC_DRBG_SHA512) {
        ret = Hash512_DRBG_Generate((DRBG_SHA512_internal *)rng->drbg512,
                                    output, sz, NULL, 0);
        if (ret == WC_NO_ERR_TRACE(DRBG_NEED_RESEED)) {
            ret = PollAndReSeed(rng, NULL, 0);
            if (ret != DRBG_SUCCESS) {
                if (ret == WC_NO_ERR_TRACE(DRBG_CONT_FAILURE))
                    rng->status = DRBG_CONT_FAILED;
                else
                    rng->status = DRBG_FAILED;
            }
            else {
                ret = Hash512_DRBG_Generate(
                    (DRBG_SHA512_internal *)rng->drbg512, output, sz,
                    NULL, 0);
            }
        }
    }
    else
#endif
    {
        ret = DRBG_FAILURE;
        rng->status = DRBG_FAILED;
    }

    if (ret == DRBG_SUCCESS) {
        ret = 0;
#ifdef WC_RNG_DEBUG_STATS
        rng->_stats_total_bytes_produced += sz;
    #ifdef WC_RNG_HAVE_RBGC
        /* chain-provenance output: generated while chain-backed */
        if (rng->RBGCStratum > 0)
            rng->_stats_RBGC_bytes_produced += sz;
    #endif
#endif
    }
    else if (ret == WC_NO_ERR_TRACE(DRBG_CONT_FAILURE)) {
        ret = DRBG_CONT_FIPS_E;
        rng->status = DRBG_CONT_FAILED;
    }
    else {
        ret = RNG_FAILURE_E;
        /* Note, Hash_DRBG_Generate() always leaves the DRBG in a
         * self-consistent state, success or failure, and can fail for retryable
         * causes (e.g. failed memory allocation), so we only update rng->status
         * above.
         */
    }
    RngAutoLockExit(rng);
#else

    /* if we get here then there is an RNG configuration error */
    ret = RNG_FAILURE_E;
    RngAutoLockExit(rng);   /* a no-op here today; the gate excludes this build */

#endif /* HAVE_HASHDRBG */
#endif /* CUSTOM_RAND_GENERATE_BLOCK */

    return ret;
}

#ifdef WC_HAVE_RNG_BANKREF
WOLFSSL_ABI
int wc_RNG_GenerateBlock(WC_RNG* rng, byte* output, word32 sz)
{
    if (rng == NULL)
        return BAD_FUNC_ARG;

    {
        int lock_ret = rng_lock_required_check(rng);
        if (lock_ret != 0)
            return lock_ret;
    }

    if (rng->flags & WC_RNG_FLAG_BANKREF) {
        int ret;
        struct wc_rng_bank_inst *bank_inst = NULL;

        ret = wc_local_rng_bank_checkout_for_bankref(rng->bankref, &bank_inst);
        if (ret != 0)
            return ret;
        if (bank_inst == NULL)
            return BAD_STATE_E;
        ret = wc_local_RNG_GenerateBlock(WC_RNG_BANK_INST_TO_RNG(bank_inst),
                                         output, sz);
        {
            int checkin_ret = wc_rng_bank_inst_checkin(&bank_inst);
            if (checkin_ret != 0) {
#ifdef WC_VERBOSE_RNG
                WOLFSSL_DEBUG_PRINTF(
                    "ERROR: wc_RNG_GenerateBlock() wc_rng_bank_inst_checkin() "
                    "failed with err %d.", checkin_ret);
#endif
                if (ret == 0)
                    ret = checkin_ret;
            }
        }
        return ret;
    }
    else
        return wc_local_RNG_GenerateBlock(rng, output, sz);
}
#endif

int wc_RNG_GenerateByte(WC_RNG* rng, byte* b)
{
    return wc_RNG_GenerateBlock(rng, b, 1);
}


int wc_FreeRng(WC_RNG* rng)
{
    int ret = 0;

    if (rng == NULL)
        return BAD_FUNC_ARG;

    /* Note, deallocation proceeds regardless of RNG lock status.  Lifecycle
     * management is the caller's responsibility, and a lock inside the object
     * cannot arbitrate deallocation.
     */

#ifdef WC_HAVE_RNG_BANKREF
    if (rng->flags & WC_RNG_FLAG_BANKREF)
        return wc_BankRef_Release(rng);
#endif /* WC_HAVE_RNG_BANKREF */

#ifdef WC_RNG_HAVE_FREE_HOOK
    if (rng->free_hook != NULL) {
        /* one-shot, cleared before firing: re-entrant frees from the hook
         * (not that they would be a good idea) can't loop. */
        wc_RNG_free_hook_cb_t free_hook = rng->free_hook;
        rng->free_hook = NULL;
        ret = free_hook(rng, rng->free_hook_arg);
        rng->free_hook_arg = NULL;
    }
#endif

#ifdef WC_RNG_HAVE_POOL
    /* single-owner teardown; the only pool deallocation site */
    if (rng->pool != NULL) {
        ForceZero(rng->pool, rng->poolSize);
        XFREE(rng->pool, rng->heap, DYNAMIC_TYPE_RNG);
        rng->pool = NULL;
        rng->poolSize = 0;
        WOLFSSL_ATOMIC_STORE(rng->poolHead, 0);
        WOLFSSL_ATOMIC_STORE(rng->poolTail, 0);
    }
#endif

#ifdef WC_RNG_HAVE_AUTO_LOCK
    RngAutoLockFree(rng);
#endif

#ifdef WC_RNG_HAVE_NEXT_SEED
    /* The stir accumulator is WC_RNG-resident (it survives DRBG teardown so
     * that blind depositors never dereference rng->drbg), so the DRBG
     * teardown below cannot wipe it -- wipe it here.  A concurrent blind
     * deposit can tear the wipe harmlessly (uncredited material, and
     * all-zeros decodes as empty/accumulating).  Note the contrast with the
     * lock word, which deliberately survives deallocation. */
    ForceZero(rng->nextStir, (word32)sizeof(rng->nextStir));
    WOLFSSL_ATOMIC_STORE(rng->nextStirLen, WC_DRBG_NEXT_SEED_EMPTY);
#endif

#if defined(WOLFSSL_ASYNC_CRYPT)
    wolfAsync_DevCtxFree(&rng->asyncDev, WOLFSSL_ASYNC_MARKER_RNG);
#endif

#ifdef HAVE_HASHDRBG
#ifndef NO_SHA256
    if (rng->drbg != NULL) {
      if (Hash_DRBG_Uninstantiate((DRBG_internal *)rng->drbg) != DRBG_SUCCESS)
            ret = RNG_FAILURE_E;

    #if !defined(WOLFSSL_NO_MALLOC) || defined(WOLFSSL_STATIC_MEMORY)
        XFREE(rng->drbg, rng->heap, DYNAMIC_TYPE_RNG);
    #elif defined(WOLFSSL_CHECK_MEM_ZERO)
        wc_MemZero_Check(rng->drbg, sizeof(DRBG_internal));
    #endif
        rng->drbg = NULL;
    }

    #ifdef WOLFSSL_SMALL_STACK_CACHE
    /* Scratch buffers are tracked independently of rng->drbg so that a
     * partial-construction failure path that nulled rng->drbg early
     * (or any future restructure that does the same) cannot leak them.
     * Free on their own NULL check rather than nesting under drbg. */
    if (rng->drbg_scratch != NULL) {
        if (Hash_DRBG_Uninstantiate((DRBG_internal *)rng->drbg_scratch)
                            != DRBG_SUCCESS)
            ret = RNG_FAILURE_E;
        XFREE(rng->drbg_scratch, rng->heap, DYNAMIC_TYPE_RNG);
        rng->drbg_scratch = NULL;
    }
    if (rng->health_check_scratch != NULL) {
        XFREE(rng->health_check_scratch, rng->heap, DYNAMIC_TYPE_TMP_BUFFER);
        rng->health_check_scratch = NULL;
    }
    #endif
#endif /* !NO_SHA256 */

#ifdef WOLFSSL_DRBG_SHA512
    if (rng->drbg512 != NULL) {
        if (Hash512_DRBG_Uninstantiate(
                (DRBG_SHA512_internal *)rng->drbg512) != DRBG_SUCCESS)
            ret = RNG_FAILURE_E;

    #if !defined(WOLFSSL_NO_MALLOC) || defined(WOLFSSL_STATIC_MEMORY)
        XFREE(rng->drbg512, rng->heap, DYNAMIC_TYPE_RNG);
    #endif
        rng->drbg512 = NULL;
    }

    #ifdef WOLFSSL_SMALL_STACK_CACHE
    /* Same independence rationale as the SHA-256 scratch above. */
    if (rng->drbg512_scratch != NULL) {
        if (Hash512_DRBG_Uninstantiate(rng->drbg512_scratch)
                                != DRBG_SUCCESS)
            ret = RNG_FAILURE_E;
        XFREE(rng->drbg512_scratch, rng->heap, DYNAMIC_TYPE_RNG);
        rng->drbg512_scratch = NULL;
    }
    if (rng->health_check_scratch_512 != NULL) {
        XFREE(rng->health_check_scratch_512, rng->heap,
               DYNAMIC_TYPE_TMP_BUFFER);
        rng->health_check_scratch_512 = NULL;
    }
    #endif
#endif /* WOLFSSL_DRBG_SHA512 */

#ifdef WOLFSSL_SMALL_STACK_CACHE
    XFREE(rng->newSeed_buf, rng->heap, DYNAMIC_TYPE_SEED);
    rng->newSeed_buf = NULL;
#endif

    rng->status = DRBG_NOT_INIT;
#endif /* HAVE_HASHDRBG */

#ifdef WOLFSSL_XILINX_CRYPT_VERSAL
    /* don't overwrite previously set error */
    if (wc_VersalTrngReset() && !ret)
        ret = WC_HW_E;
#endif

#if defined(WOLFSSL_KEEP_RNG_SEED_FD_OPEN) && defined(XCLOSE) && \
    !defined(USE_WINDOWS_API)
    if(rng->seed.seedFdOpen && rng->seed.fd != XBADFD) {
        XCLOSE(rng->seed.fd);
        rng->seed.fd = XBADFD;
        rng->seed.seedFdOpen = 0;
    }
#endif

#ifdef WC_RNG_HAVE_LOCK_FULL_MUTEX
    if (rng->flags & WC_RNG_FLAG_FULL_MUTEX) {
        /* If the latch is held, the caller is the holder (enforced when
         * _LOCK_REQUIRED) and owns the mutex: release it before
         * destruction.  A free latch means the mutex is unowned. */
        if (WOLFSSL_ATOMIC_LOAD(rng->lock) & WC_RNG_LOCK_HELD)
            (void)wc_UnLockMutex(&rng->mutex);
        (void)wc_FreeMutex(&rng->mutex);
        rng->flags &= ~WC_RNG_FLAG_FULL_MUTEX;
    }
#endif

    /* Note, rng->lock must *not* be cleared -- it may still be arbitrating
     * access even after wc_FreeRng().
     */

    return ret;
}

#ifdef HAVE_HASHDRBG
/* The original wc_RNG_HealthTest{,_ex} entry points operate on the SHA-256
 * Hash_DRBG (DRBG_internal). Gate them out under NO_SHA256; SHA-512-only
 * builds use wc_RNG_HealthTest_SHA512_ex declared further down. */
#ifndef NO_SHA256
int wc_RNG_HealthTest(int reseed, const byte* seedA, word32 seedASz,
                                  const byte* seedB, word32 seedBSz,
                                  byte* output, word32 outputSz)
{
    return wc_RNG_HealthTest_ex(reseed, NULL, 0,
                                seedA, seedASz, seedB, seedBSz,
                                output, outputSz,
                                NULL, INVALID_DEVID);
}


static WARN_UNUSED_RESULT int wc_RNG_HealthTest_ex_internal(DRBG_internal* drbg,
                                  int reseed, const byte* nonce, word32 nonceSz,
                                  const byte* seedA, word32 seedASz,
                                  const byte* seedB, word32 seedBSz,
                                  byte* output, word32 outputSz,
                                  void* heap, int devId)
{
    int ret = WC_NO_ERR_TRACE(DRBG_FAILURE);

    if (seedA == NULL || output == NULL) {
        return BAD_FUNC_ARG;
    }

    if (reseed != 0 && seedB == NULL) {
        return BAD_FUNC_ARG;
    }

    if (outputSz != RNG_HEALTH_TEST_CHECK_SIZE) {
        return BAD_FUNC_ARG;
    }

#ifdef WOLFSSL_SMALL_STACK_CACHE
    (void)heap;
    (void)devId;

    if (Hash_DRBG_Init(drbg, seedA, seedASz, nonce, nonceSz,
                        NULL, 0) != 0) {
        goto exit_rng_ht;
    }
#else
    if (Hash_DRBG_Instantiate(drbg, seedA, seedASz, nonce, nonceSz,
                              NULL, 0, heap, devId) != 0) {
        goto exit_rng_ht;
    }
#endif

    if (reseed) {
        if (Hash256_DRBG_Reseed(drbg, seedB, seedBSz, NULL, 0) != 0) {
            goto exit_rng_ht;
        }
    }

    /* This call to generate is prescribed by the NIST DRBGVS
     * procedure. The results are thrown away. The known
     * answer test checks the second block of DRBG out of
     * the generator to ensure the internal state is updated
     * as expected. */
    if (Hash_DRBG_Generate(drbg, output, outputSz, NULL, 0) != 0) {
        goto exit_rng_ht;
    }

    if (Hash_DRBG_Generate(drbg, output, outputSz, NULL, 0) != 0) {
        goto exit_rng_ht;
    }

    /* Mark success */
    ret = 0;

exit_rng_ht:

#ifndef WOLFSSL_SMALL_STACK_CACHE
    /* This is safe to call even if Hash_DRBG_Instantiate fails */
    if ((Hash_DRBG_Uninstantiate(drbg) != 0) && (ret == 0)) {
        ret = DRBG_FAILURE;
    }
#endif

    return ret;
}

int wc_RNG_HealthTest_ex(int reseed, const byte* nonce, word32 nonceSz,
                                  const byte* seedA, word32 seedASz,
                                  const byte* seedB, word32 seedBSz,
                                  byte* output, word32 outputSz,
                                  void* heap, int devId)
{
    int ret = WC_NO_ERR_TRACE(WC_FAILURE);
    DRBG_internal* drbg;
#ifndef WOLFSSL_SMALL_STACK
    DRBG_internal  drbg_var;
#endif

#ifdef WOLFSSL_SMALL_STACK
    drbg = (DRBG_internal*)XMALLOC(sizeof(DRBG_internal), heap,
        DYNAMIC_TYPE_RNG);
    if (drbg == NULL) {
        return MEMORY_E;
    }
#else
    drbg = &drbg_var;
#endif

#ifdef WOLFSSL_SMALL_STACK_CACHE
    ret = Hash_DRBG_Instantiate(drbg,
                    NULL /* seed */, 0, NULL /* nonce */, 0,
                    NULL /* perso */, 0, heap, devId);
    if (ret == 0)
#endif
    {
        ret = wc_RNG_HealthTest_ex_internal(
                drbg, reseed, nonce, nonceSz, seedA, seedASz,
                seedB, seedBSz, output, outputSz, heap, devId);
#ifdef WOLFSSL_SMALL_STACK_CACHE
        Hash_DRBG_Uninstantiate(drbg);
#endif
    }
    WC_FREE_VAR_EX(drbg, heap, DYNAMIC_TYPE_RNG);

    if (ret > 0) {
        /* Translate protocol-domain codes at the public boundary; negative
         * codes (MEMORY_E, BAD_FUNC_ARG) pass verbatim. */
        ret = WC_FAILURE;
    }
    return ret;
}
#endif /* !NO_SHA256 - wc_RNG_HealthTest{,_ex,_ex_internal} */


const FLASH_QUALIFIER byte seedA_data[] = {
    0x63, 0x36, 0x33, 0x77, 0xe4, 0x1e, 0x86, 0x46, 0x8d, 0xeb, 0x0a, 0xb4,
    0xa8, 0xed, 0x68, 0x3f, 0x6a, 0x13, 0x4e, 0x47, 0xe0, 0x14, 0xc7, 0x00,
    0x45, 0x4e, 0x81, 0xe9, 0x53, 0x58, 0xa5, 0x69, 0x80, 0x8a, 0xa3, 0x8f,
    0x2a, 0x72, 0xa6, 0x23, 0x59, 0x91, 0x5a, 0x9f, 0x8a, 0x04, 0xca, 0x68
};

const FLASH_QUALIFIER byte reseedSeedA_data[] = {
    0xe6, 0x2b, 0x8a, 0x8e, 0xe8, 0xf1, 0x41, 0xb6, 0x98, 0x05, 0x66, 0xe3,
    0xbf, 0xe3, 0xc0, 0x49, 0x03, 0xda, 0xd4, 0xac, 0x2c, 0xdf, 0x9f, 0x22,
    0x80, 0x01, 0x0a, 0x67, 0x39, 0xbc, 0x83, 0xd3
};

const FLASH_QUALIFIER byte outputA_data[] = {
    0x04, 0xee, 0xc6, 0x3b, 0xb2, 0x31, 0xdf, 0x2c, 0x63, 0x0a, 0x1a, 0xfb,
    0xe7, 0x24, 0x94, 0x9d, 0x00, 0x5a, 0x58, 0x78, 0x51, 0xe1, 0xaa, 0x79,
    0x5e, 0x47, 0x73, 0x47, 0xc8, 0xb0, 0x56, 0x62, 0x1c, 0x18, 0xbd, 0xdc,
    0xdd, 0x8d, 0x99, 0xfc, 0x5f, 0xc2, 0xb9, 0x20, 0x53, 0xd8, 0xcf, 0xac,
    0xfb, 0x0b, 0xb8, 0x83, 0x12, 0x05, 0xfa, 0xd1, 0xdd, 0xd6, 0xc0, 0x71,
    0x31, 0x8a, 0x60, 0x18, 0xf0, 0x3b, 0x73, 0xf5, 0xed, 0xe4, 0xd4, 0xd0,
    0x71, 0xf9, 0xde, 0x03, 0xfd, 0x7a, 0xea, 0x10, 0x5d, 0x92, 0x99, 0xb8,
    0xaf, 0x99, 0xaa, 0x07, 0x5b, 0xdb, 0x4d, 0xb9, 0xaa, 0x28, 0xc1, 0x8d,
    0x17, 0x4b, 0x56, 0xee, 0x2a, 0x01, 0x4d, 0x09, 0x88, 0x96, 0xff, 0x22,
    0x82, 0xc9, 0x55, 0xa8, 0x19, 0x69, 0xe0, 0x69, 0xfa, 0x8c, 0xe0, 0x07,
    0xa1, 0x80, 0x18, 0x3a, 0x07, 0xdf, 0xae, 0x17
};

const FLASH_QUALIFIER byte seedB_data[] = {
    0xa6, 0x5a, 0xd0, 0xf3, 0x45, 0xdb, 0x4e, 0x0e, 0xff, 0xe8, 0x75, 0xc3,
    0xa2, 0xe7, 0x1f, 0x42, 0xc7, 0x12, 0x9d, 0x62, 0x0f, 0xf5, 0xc1, 0x19,
    0xa9, 0xef, 0x55, 0xf0, 0x51, 0x85, 0xe0, 0xfb, /* nonce next */
    0x85, 0x81, 0xf9, 0x31, 0x75, 0x17, 0x27, 0x6e, 0x06, 0xe9, 0x60, 0x7d,
    0xdb, 0xcb, 0xcc, 0x2e
};

const FLASH_QUALIFIER byte outputB_data[] = {
    0xd3, 0xe1, 0x60, 0xc3, 0x5b, 0x99, 0xf3, 0x40, 0xb2, 0x62, 0x82, 0x64,
    0xd1, 0x75, 0x10, 0x60, 0xe0, 0x04, 0x5d, 0xa3, 0x83, 0xff, 0x57, 0xa5,
    0x7d, 0x73, 0xa6, 0x73, 0xd2, 0xb8, 0xd8, 0x0d, 0xaa, 0xf6, 0xa6, 0xc3,
    0x5a, 0x91, 0xbb, 0x45, 0x79, 0xd7, 0x3f, 0xd0, 0xc8, 0xfe, 0xd1, 0x11,
    0xb0, 0x39, 0x13, 0x06, 0x82, 0x8a, 0xdf, 0xed, 0x52, 0x8f, 0x01, 0x81,
    0x21, 0xb3, 0xfe, 0xbd, 0xc3, 0x43, 0xe7, 0x97, 0xb8, 0x7d, 0xbb, 0x63,
    0xdb, 0x13, 0x33, 0xde, 0xd9, 0xd1, 0xec, 0xe1, 0x77, 0xcf, 0xa6, 0xb7,
    0x1f, 0xe8, 0xab, 0x1d, 0xa4, 0x66, 0x24, 0xed, 0x64, 0x15, 0xe5, 0x1c,
    0xcd, 0xe2, 0xc7, 0xca, 0x86, 0xe2, 0x83, 0x99, 0x0e, 0xea, 0xeb, 0x91,
    0x12, 0x04, 0x15, 0x52, 0x8b, 0x22, 0x95, 0x91, 0x02, 0x81, 0xb0, 0x2d,
    0xd4, 0x31, 0xf4, 0xc9, 0xf7, 0x04, 0x27, 0xdf
};


/* SHA-512 DRBG KAT vectors for local health test.
 * Source: NIST CAVP Hash_DRBG.rsp, [SHA-512], PredictionResistance=False,
 * EntropyInputLen=256, NonceLen=128, PersonalizationStringLen=0,
 * AdditionalInputLen=0, ReturnedBitsLen=2048. */
#ifdef WOLFSSL_DRBG_SHA512

/* Reseed test vectors (COUNT=0 from reseed section) */
static const byte sha512_seedA_data[] = {
    /* EntropyInput (32 bytes) || Nonce (16 bytes) */
    0x31, 0x44, 0xe1, 0x7a, 0x10, 0xc8, 0x56, 0x12,
    0x97, 0x64, 0xf5, 0x8f, 0xd8, 0xe4, 0x23, 0x10,
    0x20, 0x54, 0x69, 0x96, 0xc0, 0xbf, 0x6c, 0xff,
    0x8e, 0x91, 0xc2, 0x4e, 0xe0, 0x9b, 0xe3, 0x33,
    0xb1, 0x6f, 0xcb, 0x1c, 0xf0, 0xc0, 0x10, 0xf3,
    0x1f, 0xea, 0xb7, 0x33, 0x58, 0x8b, 0x8e, 0x04
};
static const byte sha512_reseedSeedA_data[] = {
    /* EntropyInputReseed (32 bytes) */
    0xa0, 0xb3, 0x58, 0x4c, 0x2c, 0x84, 0x12, 0xf6,
    0x18, 0x40, 0x68, 0x34, 0x40, 0x4d, 0x1e, 0xb0,
    0xce, 0x99, 0x9b, 0xa2, 0x89, 0x66, 0x05, 0x4d,
    0x7e, 0x49, 0x7e, 0x0d, 0xb6, 0x08, 0xb9, 0x67
};
static const byte sha512_outputA_data[] = {
    0xef, 0xa3, 0x5d, 0xd0, 0x36, 0x2a, 0xdb, 0x76,
    0x26, 0x45, 0x6b, 0x36, 0xfa, 0xc7, 0x4d, 0x3c,
    0x28, 0xd0, 0x1d, 0x92, 0x64, 0x20, 0x27, 0x5a,
    0x28, 0xbe, 0xa9, 0xc9, 0xdd, 0x75, 0x47, 0xc1,
    0x5e, 0x79, 0x31, 0x85, 0x2a, 0xc1, 0x27, 0x70,
    0x76, 0x56, 0x75, 0x35, 0x23, 0x9c, 0x1f, 0x42,
    0x9c, 0x7f, 0x75, 0xcf, 0x74, 0xc2, 0x26, 0x7d,
    0xeb, 0x6a, 0x3e, 0x59, 0x6c, 0xf3, 0x26, 0x15,
    0x6c, 0x79, 0x69, 0x41, 0x28, 0x3b, 0x8d, 0x58,
    0x3f, 0x17, 0x1c, 0x2f, 0x6e, 0x33, 0x23, 0xf7,
    0x55, 0x5e, 0x1b, 0x18, 0x1f, 0xfd, 0xa3, 0x05,
    0x07, 0x21, 0x0c, 0xb1, 0xf5, 0x89, 0xb2, 0x3c,
    0xd7, 0x18, 0x80, 0xfd, 0x44, 0x37, 0x0c, 0xac,
    0xf4, 0x33, 0x75, 0xb0, 0xdb, 0x7e, 0x33, 0x6f,
    0x12, 0xb3, 0x09, 0xbf, 0xd4, 0xf6, 0x10, 0xbb,
    0x8f, 0x20, 0xe1, 0xa1, 0x5e, 0x25, 0x3a, 0x4f,
    0xe5, 0x11, 0xa0, 0x27, 0x96, 0x8d, 0xf0, 0xb1,
    0x05, 0xa1, 0xd7, 0x3a, 0xff, 0x7c, 0x7a, 0x82,
    0x6d, 0x39, 0xf6, 0x40, 0xdf, 0xb8, 0xf5, 0x22,
    0x25, 0x9e, 0xd4, 0x02, 0x28, 0x2e, 0x2c, 0x2e,
    0x9d, 0x3a, 0x49, 0x8f, 0x51, 0x72, 0x5f, 0xe4,
    0x14, 0x1b, 0x06, 0xda, 0x55, 0x98, 0xa4, 0x2a,
    0xc1, 0xe0, 0x49, 0x4e, 0x99, 0x7d, 0x56, 0x6a,
    0x1a, 0x39, 0xb6, 0x76, 0xb9, 0x6a, 0x60, 0x03,
    0xa4, 0xc5, 0xdb, 0x84, 0xf2, 0x46, 0x58, 0x4e,
    0xe6, 0x5a, 0xf7, 0x0f, 0xf2, 0x16, 0x02, 0x78,
    0x16, 0x6d, 0xa1, 0x6d, 0x91, 0xc9, 0xb8, 0xf2,
    0xde, 0xb0, 0x27, 0x51, 0xa1, 0x08, 0x8a, 0xd6,
    0xbe, 0x4e, 0x80, 0xef, 0x96, 0x6e, 0xb7, 0x3e,
    0x66, 0xbc, 0x87, 0xca, 0xd8, 0x7c, 0x77, 0xc0,
    0xb3, 0x4a, 0x21, 0xba, 0x1d, 0xa0, 0xba, 0x6d,
    0x16, 0xca, 0x50, 0x46, 0xdc, 0x4a, 0xbd, 0xa0
};

/* No-reseed test vectors (COUNT=0 from no-reseed section) */
static const byte sha512_seedB_data[] = {
    /* EntropyInput (32 bytes) || Nonce (16 bytes) */
    0x6b, 0x50, 0xa7, 0xd8, 0xf8, 0xa5, 0x5d, 0x7a,
    0x3d, 0xf8, 0xbb, 0x40, 0xbc, 0xc3, 0xb7, 0x22,
    0xd8, 0x70, 0x8d, 0xe6, 0x7f, 0xda, 0x01, 0x0b,
    0x03, 0xc4, 0xc8, 0x4d, 0x72, 0x09, 0x6f, 0x8c,
    0x3e, 0xc6, 0x49, 0xcc, 0x62, 0x56, 0xd9, 0xfa,
    0x31, 0xdb, 0x7a, 0x29, 0x04, 0xaa, 0xf0, 0x25
};
static const byte sha512_outputB_data[] = {
    0x95, 0xb7, 0xf1, 0x7e, 0x98, 0x02, 0xd3, 0x57,
    0x73, 0x92, 0xc6, 0xa9, 0xc0, 0x80, 0x83, 0xb6,
    0x7d, 0xd1, 0x29, 0x22, 0x65, 0xb5, 0xf4, 0x2d,
    0x23, 0x7f, 0x1c, 0x55, 0xbb, 0x9b, 0x10, 0xbf,
    0xcf, 0xd8, 0x2c, 0x77, 0xa3, 0x78, 0xb8, 0x26,
    0x6a, 0x00, 0x99, 0x14, 0x3b, 0x3c, 0x2d, 0x64,
    0x61, 0x1e, 0xee, 0xb6, 0x9a, 0xcd, 0xc0, 0x55,
    0x95, 0x7c, 0x13, 0x9e, 0x8b, 0x19, 0x0c, 0x7a,
    0x06, 0x95, 0x5f, 0x2c, 0x79, 0x7c, 0x27, 0x78,
    0xde, 0x94, 0x03, 0x96, 0xa5, 0x01, 0xf4, 0x0e,
    0x91, 0x39, 0x6a, 0xcf, 0x8d, 0x7e, 0x45, 0xeb,
    0xdb, 0xb5, 0x3b, 0xbf, 0x8c, 0x97, 0x52, 0x30,
    0xd2, 0xf0, 0xff, 0x91, 0x06, 0xc7, 0x61, 0x19,
    0xae, 0x49, 0x8e, 0x7f, 0xbc, 0x03, 0xd9, 0x0f,
    0x8e, 0x4c, 0x51, 0x62, 0x7a, 0xed, 0x5c, 0x8d,
    0x42, 0x63, 0xd5, 0xd2, 0xb9, 0x78, 0x87, 0x3a,
    0x0d, 0xe5, 0x96, 0xee, 0x6d, 0xc7, 0xf7, 0xc2,
    0x9e, 0x37, 0xee, 0xe8, 0xb3, 0x4c, 0x90, 0xdd,
    0x1c, 0xf6, 0xa9, 0xdd, 0xb2, 0x2b, 0x4c, 0xbd,
    0x08, 0x6b, 0x14, 0xb3, 0x5d, 0xe9, 0x3d, 0xa2,
    0xd5, 0xcb, 0x18, 0x06, 0x69, 0x8c, 0xbd, 0x7b,
    0xbb, 0x67, 0xbf, 0xe3, 0xd3, 0x1f, 0xd2, 0xd1,
    0xdb, 0xd2, 0xa1, 0xe0, 0x58, 0xa3, 0xeb, 0x99,
    0xd7, 0xe5, 0x1f, 0x1a, 0x93, 0x8e, 0xed, 0x5e,
    0x1c, 0x1d, 0xe2, 0x3a, 0x6b, 0x43, 0x45, 0xd3,
    0x19, 0x14, 0x09, 0xf9, 0x2f, 0x39, 0xb3, 0x67,
    0x0d, 0x8d, 0xbf, 0xb6, 0x35, 0xd8, 0xe6, 0xa3,
    0x69, 0x32, 0xd8, 0x10, 0x33, 0xd1, 0x44, 0x8d,
    0x63, 0xb4, 0x03, 0xdd, 0xf8, 0x8e, 0x12, 0x1b,
    0x6e, 0x81, 0x9a, 0xc3, 0x81, 0x22, 0x6c, 0x13,
    0x21, 0xe4, 0xb0, 0x86, 0x44, 0xf6, 0x72, 0x7c,
    0x36, 0x8c, 0x5a, 0x9f, 0x7a, 0x4b, 0x3e, 0xe2
};
#endif /* WOLFSSL_DRBG_SHA512 */


static int wc_RNG_HealthTestLocal(WC_RNG* rng, int reseed, void* heap,
                                  int devId)
{
    int ret = 0;

#ifdef WOLFSSL_DRBG_SHA512
    /* SHA-512 DRBG health test path */
    if (rng->drbgType == WC_DRBG_SHA512) {
    #ifdef WOLFSSL_SMALL_STACK_CACHE
        byte *check512 = rng->health_check_scratch_512;
        DRBG_SHA512_internal* drbg512 = rng->drbg512_scratch;
    #else
        WC_DECLARE_VAR(check512, byte, RNG_HEALTH_TEST_CHECK_SIZE_SHA512, 0);
        WC_DECLARE_VAR(drbg512, DRBG_SHA512_internal, 1, 0);

        WC_ALLOC_VAR_EX(check512, byte, RNG_HEALTH_TEST_CHECK_SIZE_SHA512,
            heap, DYNAMIC_TYPE_TMP_BUFFER, return MEMORY_E);
        WC_ALLOC_VAR_EX(drbg512, DRBG_SHA512_internal, 1, heap,
            DYNAMIC_TYPE_TMP_BUFFER, WC_DO_NOTHING);
        #ifdef WC_DECLARE_VAR_IS_HEAP_ALLOC
        if (drbg512 == NULL) {
            WC_FREE_VAR_EX(check512, heap, DYNAMIC_TYPE_TMP_BUFFER);
            return MEMORY_E;
        }
        #endif
    #endif

        if (reseed) {
            /* Reseed test with NIST CAVP SHA-512 vectors */
            ret = wc_RNG_HealthTest_SHA512_ex_internal(
                        drbg512, 1, NULL, 0, NULL, 0,
                        sha512_seedA_data, sizeof(sha512_seedA_data),
                        sha512_reseedSeedA_data,
                        sizeof(sha512_reseedSeedA_data),
                        NULL, 0, NULL, 0,
                        check512, RNG_HEALTH_TEST_CHECK_SIZE_SHA512,
                        heap, devId);
            if (ret == 0) {
                if (ConstantCompare(check512, sha512_outputA_data,
                                    RNG_HEALTH_TEST_CHECK_SIZE_SHA512) != 0)
                    ret = DRBG_CONT_FAILURE;
            }
        }
        else {
            /* No-reseed test with NIST CAVP SHA-512 vectors */
            ret = wc_RNG_HealthTest_SHA512_ex_internal(
                        drbg512, 0, NULL, 0, NULL, 0,
                        sha512_seedB_data, sizeof(sha512_seedB_data),
                        NULL, 0,
                        NULL, 0, NULL, 0,
                        check512, RNG_HEALTH_TEST_CHECK_SIZE_SHA512,
                        heap, devId);
            if (ret == 0) {
                if (ConstantCompare(check512, sha512_outputB_data,
                                    RNG_HEALTH_TEST_CHECK_SIZE_SHA512) != 0)
                    ret = DRBG_CONT_FAILURE;
            }
        }

    #ifndef WOLFSSL_SMALL_STACK_CACHE
        WC_FREE_VAR_EX(check512, heap, DYNAMIC_TYPE_TMP_BUFFER);
        WC_FREE_VAR_EX(drbg512, heap, DYNAMIC_TYPE_TMP_BUFFER);
    #endif
        return ret;
    }
#endif /* WOLFSSL_DRBG_SHA512 */

    /* SHA-256 DRBG health test path (original) */
#ifndef NO_SHA256
    {
#ifdef WOLFSSL_SMALL_STACK_CACHE
    byte *check = rng->health_check_scratch;
    DRBG_internal* drbg = (DRBG_internal *)rng->drbg_scratch;
#else
    WC_DECLARE_VAR(check, byte, RNG_HEALTH_TEST_CHECK_SIZE, 0);
    WC_DECLARE_VAR(drbg, DRBG_internal, 1, 0);

    (void)rng;

    WC_ALLOC_VAR_EX(check, byte, RNG_HEALTH_TEST_CHECK_SIZE, heap,
        DYNAMIC_TYPE_TMP_BUFFER, return MEMORY_E);
    WC_ALLOC_VAR_EX(drbg, DRBG_internal, 1, heap,
        DYNAMIC_TYPE_TMP_BUFFER, WC_DO_NOTHING);
    #ifdef WC_DECLARE_VAR_IS_HEAP_ALLOC
    if (drbg == NULL) {
        WC_FREE_VAR_EX(check, heap, DYNAMIC_TYPE_TMP_BUFFER);
        return MEMORY_E;
    }
    #endif
#endif

    if (reseed) {
#ifdef WOLFSSL_USE_FLASHMEM
        byte* seedA = (byte*)XMALLOC(sizeof(seedA_data), heap,
                             DYNAMIC_TYPE_TMP_BUFFER);
        byte* reseedSeedA = (byte*)XMALLOC(sizeof(reseedSeedA_data), heap,
                             DYNAMIC_TYPE_TMP_BUFFER);
        byte* outputA = (byte*)XMALLOC(sizeof(outputA_data), heap,
                             DYNAMIC_TYPE_TMP_BUFFER);

        if (!seedA || !reseedSeedA || !outputA) {
            XFREE(seedA, heap, DYNAMIC_TYPE_TMP_BUFFER);
            XFREE(reseedSeedA, heap, DYNAMIC_TYPE_TMP_BUFFER);
            XFREE(outputA, heap, DYNAMIC_TYPE_TMP_BUFFER);
            ret = MEMORY_E;
        }
        else {
            XMEMCPY_P(seedA, seedA_data, sizeof(seedA_data));
            XMEMCPY_P(reseedSeedA, reseedSeedA_data, sizeof(reseedSeedA_data));
            XMEMCPY_P(outputA, outputA_data, sizeof(outputA_data));
#else
        const byte* seedA = seedA_data;
        const byte* reseedSeedA = reseedSeedA_data;
        const byte* outputA = outputA_data;
#endif
        ret = wc_RNG_HealthTest_ex_internal(drbg, 1, NULL, 0,
                                   seedA, sizeof(seedA_data),
                                   reseedSeedA, sizeof(reseedSeedA_data),
                                   check, RNG_HEALTH_TEST_CHECK_SIZE,
                                   heap, devId);
        if (ret == 0) {
            if (ConstantCompare(check, outputA,
                                RNG_HEALTH_TEST_CHECK_SIZE) != 0)
                ret = DRBG_CONT_FAILURE;
        }

#ifdef WOLFSSL_USE_FLASHMEM
            XFREE(seedA, NULL, DYNAMIC_TYPE_TMP_BUFFER);
            XFREE(reseedSeedA, NULL, DYNAMIC_TYPE_TMP_BUFFER);
            XFREE(outputA, NULL, DYNAMIC_TYPE_TMP_BUFFER);
        }
#endif
    }
    else {
#ifdef WOLFSSL_USE_FLASHMEM
        byte* seedB = (byte*)XMALLOC(sizeof(seedB_data), heap,
                             DYNAMIC_TYPE_TMP_BUFFER);
        byte* outputB = (byte*)XMALLOC(sizeof(outputB_data), heap,
                               DYNAMIC_TYPE_TMP_BUFFER);

        if (!seedB || !outputB) {
            XFREE(seedB, heap, DYNAMIC_TYPE_TMP_BUFFER);
            XFREE(outputB, heap, DYNAMIC_TYPE_TMP_BUFFER);
            ret = MEMORY_E;
        }
        else {
            XMEMCPY_P(seedB, seedB_data, sizeof(seedB_data));
            XMEMCPY_P(outputB, outputB_data, sizeof(outputB_data));
#else
        const byte* seedB = seedB_data;
        const byte* outputB = outputB_data;
#endif
#if defined(DEBUG_WOLFSSL)
        WOLFSSL_MSG_EX("RNG_HEALTH_TEST_CHECK_SIZE = %d",
                        RNG_HEALTH_TEST_CHECK_SIZE);
        WOLFSSL_MSG_EX("sizeof(seedB_data)         = %d",
                        (int)sizeof(outputB_data));
#endif
        ret = wc_RNG_HealthTest_ex_internal(drbg, 0, NULL, 0,
                                   seedB, sizeof(seedB_data),
                                   NULL, 0,
                                   check, RNG_HEALTH_TEST_CHECK_SIZE,
                                   heap, devId);
        if (ret != 0) {
            #if defined(DEBUG_WOLFSSL)
            WOLFSSL_MSG_EX("RNG_HealthTest failed: err = %d", ret);
            #endif
        }
        else {
            ret = ConstantCompare(check, outputB,
                                RNG_HEALTH_TEST_CHECK_SIZE);
            if (ret != 0) {
                #if defined(DEBUG_WOLFSSL)
                WOLFSSL_MSG_EX("Random ConstantCompare failed: err = %d", ret);
                #endif
                ret = DRBG_CONT_FAILURE;
            }
        }

        /* The previous test cases use a large seed instead of a seed and nonce.
         * seedB is actually from a test case with a seed and nonce, and
         * just concatenates them. The pivot point between seed and nonce is
         * byte 32, feed them into the health test separately. */
        if (ret == 0) {
            ret = wc_RNG_HealthTest_ex_internal(drbg, 0,
                                       seedB + 32, sizeof(seedB_data) - 32,
                                       seedB, 32,
                                       NULL, 0,
                                       check, RNG_HEALTH_TEST_CHECK_SIZE,
                                       heap, devId);
            if (ret == 0) {
                if (ConstantCompare(check, outputB, sizeof(outputB_data)) != 0)
                    ret = DRBG_CONT_FAILURE;
            }
        }

#ifdef WOLFSSL_USE_FLASHMEM
            XFREE(seedB, heap, DYNAMIC_TYPE_TMP_BUFFER);
            XFREE(outputB, heap, DYNAMIC_TYPE_TMP_BUFFER);
        }
#endif
    }

#ifndef WOLFSSL_SMALL_STACK_CACHE
    WC_FREE_VAR_EX(check, heap, DYNAMIC_TYPE_TMP_BUFFER);
    WC_FREE_VAR_EX(drbg, heap, DYNAMIC_TYPE_TMP_BUFFER);
#endif
    } /* SHA-256 path */
#endif /* !NO_SHA256 */

    return ret;
}

/* ====================================================================== */
/* SHA-512 Health Test API                                                 */
/* ====================================================================== */
#ifdef WOLFSSL_DRBG_SHA512

static int wc_RNG_HealthTest_SHA512_ex_internal(DRBG_SHA512_internal* drbg,
                                  int reseed, const byte* nonce, word32 nonceSz,
                                  const byte* perso, word32 persoSz,
                                  const byte* seedA, word32 seedASz,
                                  const byte* seedB, word32 seedBSz,
                                  const byte* additionalA, word32 additionalASz,
                                  const byte* additionalB, word32 additionalBSz,
                                  byte* output, word32 outputSz,
                                  void* heap, int devId)
{
    int ret = WC_NO_ERR_TRACE(DRBG_FAILURE);

    if (seedA == NULL || output == NULL) {
        return BAD_FUNC_ARG;
    }

    if (reseed != 0 && seedB == NULL) {
        return BAD_FUNC_ARG;
    }

    if (outputSz != RNG_HEALTH_TEST_CHECK_SIZE_SHA512) {
        return BAD_FUNC_ARG;
    }

#ifdef WOLFSSL_SMALL_STACK_CACHE
    (void)heap;
    (void)devId;

    if (Hash512_DRBG_Init(drbg, seedA, seedASz, nonce, nonceSz,
                          perso, persoSz) != 0) {
        goto exit_rng_ht512;
    }
#else
    if (Hash512_DRBG_Instantiate(drbg, seedA, seedASz, nonce, nonceSz,
                              perso, persoSz, heap, devId) != 0) {
        goto exit_rng_ht512;
    }
#endif

    if (reseed) {
        if (Hash512_DRBG_Reseed(drbg, seedB, seedBSz, NULL, 0) != 0)
        {
            goto exit_rng_ht512;
        }
    }

    /* First generate: output discarded per NIST DRBGVS procedure */
    if (Hash512_DRBG_Generate(drbg, output, outputSz,
                              additionalA, additionalASz) != 0) {
        goto exit_rng_ht512;
    }

    /* Second generate: this is the actual test output */
    if (Hash512_DRBG_Generate(drbg, output, outputSz,
                              additionalB, additionalBSz) != 0) {
        goto exit_rng_ht512;
    }

    ret = 0;

exit_rng_ht512:

#ifndef WOLFSSL_SMALL_STACK_CACHE
    if ((Hash512_DRBG_Uninstantiate(drbg) != 0) && (ret == 0)) {
        ret = DRBG_FAILURE;
    }
#endif

    return ret;
}


/* Extended API with personalization string and additional input
 * for ACVP testing */
int wc_RNG_HealthTest_SHA512_ex(int reseed,
                                const byte* nonce, word32 nonceSz,
                                const byte* persoString, word32 persoStringSz,
                                const byte* seedA, word32 seedASz,
                                const byte* seedB, word32 seedBSz,
                                const byte* additionalA, word32 additionalASz,
                                const byte* additionalB, word32 additionalBSz,
                                byte* output, word32 outputSz,
                                void* heap, int devId)
{
    int ret = WC_NO_ERR_TRACE(WC_FAILURE);
    DRBG_SHA512_internal* drbg;
#ifndef WOLFSSL_SMALL_STACK
    DRBG_SHA512_internal  drbg_var;
#endif

    if (seedA == NULL || output == NULL) {
        return BAD_FUNC_ARG;
    }

    if (outputSz != RNG_HEALTH_TEST_CHECK_SIZE_SHA512) {
        return BAD_FUNC_ARG;
    }

#ifdef WOLFSSL_SMALL_STACK
    drbg = (DRBG_SHA512_internal*)XMALLOC(sizeof(DRBG_SHA512_internal), heap,
        DYNAMIC_TYPE_RNG);
    if (drbg == NULL) {
        return MEMORY_E;
    }
#else
    drbg = &drbg_var;
#endif

    /* SP 800-90A Sec 10.1.1.2: personalization string is concatenated
     * with entropy during instantiation via Hash_df. */
    ret = Hash512_DRBG_Instantiate(drbg, seedA, seedASz, nonce, nonceSz,
                                   persoString, persoStringSz, heap, devId);
    if (ret != 0) {
        goto exit_sha512_ex;
    }

    if (reseed) {
        if (seedB != NULL && seedBSz > 0) {
            ret = Hash512_DRBG_Reseed(drbg, seedB, seedBSz, NULL, 0);
            if (ret != 0) goto exit_sha512_ex;
        }
    }

    /* First generate (output discarded per NIST procedure) */
    ret = Hash512_DRBG_Generate(drbg, output, outputSz,
                                additionalA, additionalASz);
    if (ret != 0) goto exit_sha512_ex;

    /* Second generate (this is the actual output) */
    ret = Hash512_DRBG_Generate(drbg, output, outputSz,
                                additionalB, additionalBSz);

exit_sha512_ex:
    (void)Hash512_DRBG_Uninstantiate(drbg);

#ifdef WOLFSSL_SMALL_STACK
    XFREE(drbg, heap, DYNAMIC_TYPE_RNG);
#endif

    return (ret == DRBG_SUCCESS) ? 0 : -1;
}


/* Simple API matching wc_RNG_HealthTest() pattern - entropy+nonce only */
int wc_RNG_HealthTest_SHA512(int reseed,
                             const byte* seedA, word32 seedASz,
                             const byte* seedB, word32 seedBSz,
                             byte* output, word32 outputSz)
{
    int ret = WC_NO_ERR_TRACE(WC_FAILURE);
    DRBG_SHA512_internal* drbg;
#ifndef WOLFSSL_SMALL_STACK
    DRBG_SHA512_internal  drbg_var;
#endif

#ifdef WOLFSSL_SMALL_STACK
    drbg = (DRBG_SHA512_internal*)XMALLOC(sizeof(DRBG_SHA512_internal), NULL,
        DYNAMIC_TYPE_RNG);
    if (drbg == NULL) {
        return MEMORY_E;
    }
#else
    drbg = &drbg_var;
#endif

#ifdef WOLFSSL_SMALL_STACK_CACHE
    ret = Hash512_DRBG_Instantiate(drbg,
                    NULL /* seed */, 0, NULL /* nonce */, 0,
                    NULL, 0, NULL, INVALID_DEVID);
    if (ret == 0)
#endif
    {
        ret = wc_RNG_HealthTest_SHA512_ex_internal(
                drbg, reseed, NULL, 0, NULL, 0,
                seedA, seedASz, seedB, seedBSz,
                NULL, 0, NULL, 0,
                output, outputSz, NULL, INVALID_DEVID);
#ifdef WOLFSSL_SMALL_STACK_CACHE
        Hash512_DRBG_Uninstantiate(drbg);
#endif
    }
    WC_FREE_VAR_EX(drbg, NULL, DYNAMIC_TYPE_RNG);

    if (ret > 0) {
        /* Translate protocol-domain codes at the public boundary; negative
         * codes (MEMORY_E, BAD_FUNC_ARG) pass verbatim. */
        ret = WC_FAILURE;
    }
    return ret;
}

#endif /* WOLFSSL_DRBG_SHA512 */

#if !defined(NO_SHA256) && !defined(HAVE_SELFTEST) && \
    (!defined(HAVE_FIPS) || FIPS_VERSION3_GE(7,0,0))
/* Extended SHA-256 Hash_DRBG health test per SP 800-90A.
 * Supports flexible output sizes, prediction resistance, personalization
 * strings, and additional input.
 *
 * predResistance=0: Instantiate(entropyA, nonce, perso) ->
 *                   Reseed(entropyB, additionalReseed) ->
 *                   Gen1(additionalA, discard) -> Gen2(additionalB, keep)
 * predResistance=1: Instantiate(entropyA, nonce, perso) ->
 *                   Reseed(entropyB, additionalA)+Gen1(NULL, discard) ->
 *                   Reseed(entropyC, additionalB)+Gen2(NULL, keep)
 */
int wc_RNG_HealthTest_SHA256_ex(
    int predResistance,
    const byte* nonce, word32 nonceSz,
    const byte* persoString, word32 persoStringSz,
    const byte* entropyA, word32 entropyASz,
    const byte* entropyB, word32 entropyBSz,
    const byte* entropyC, word32 entropyCsz,
    const byte* additionalA, word32 additionalASz,
    const byte* additionalB, word32 additionalBSz,
    const byte* additionalReseed, word32 additionalReseedSz,
    byte* output, word32 outputSz,
    void* heap, int devId)
{
    int ret;
    DRBG_internal* drbg;
#ifndef WOLFSSL_SMALL_STACK
    DRBG_internal  drbg_var;
#endif

    if (entropyA == NULL || output == NULL || outputSz == 0) {
        return BAD_FUNC_ARG;
    }

#ifdef WOLFSSL_SMALL_STACK
    drbg = (DRBG_internal*)XMALLOC(sizeof(DRBG_internal), heap,
        DYNAMIC_TYPE_RNG);
    if (drbg == NULL) {
        return MEMORY_E;
    }
#else
    drbg = &drbg_var;
#endif

    /* Instantiate with entropy, nonce, personalization string */
    ret = Hash_DRBG_Instantiate(drbg, entropyA, entropyASz, nonce, nonceSz,
                                persoString, persoStringSz, heap, devId);
    if (ret != 0) goto exit_sha256_ex;

    if (predResistance) {
        /* Prediction resistance mode per SP 800-90A 9.3.1:
         * additional_input is passed to Reseed, Generate gets NULL */

        /* Reseed 1 with additionalA, then Generate 1 with NULL (discard) */
        if (entropyB != NULL && entropyBSz > 0) {
            ret = Hash256_DRBG_Reseed(drbg, entropyB, entropyBSz,
                                      additionalA, additionalASz);
            if (ret != 0) goto exit_sha256_ex;
        }
        ret = Hash_DRBG_Generate(drbg, output, outputSz, NULL, 0);
        if (ret != 0) goto exit_sha256_ex;

        /* Reseed 2 with additionalB, then Generate 2 with NULL (keep) */
        if (entropyC != NULL && entropyCsz > 0) {
            ret = Hash256_DRBG_Reseed(drbg, entropyC, entropyCsz,
                                      additionalB, additionalBSz);
            if (ret != 0) goto exit_sha256_ex;
        }
        ret = Hash_DRBG_Generate(drbg, output, outputSz, NULL, 0);
    }
    else {
        /* Standard mode: explicit reseed, then two generates */
        if (entropyB != NULL && entropyBSz > 0) {
            ret = Hash256_DRBG_Reseed(drbg, entropyB, entropyBSz,
                                      additionalReseed, additionalReseedSz);
            if (ret != 0) goto exit_sha256_ex;
        }

        /* Generate 1 (output discarded per NIST DRBGVS procedure) */
        ret = Hash_DRBG_Generate(drbg, output, outputSz,
                                 additionalA, additionalASz);
        if (ret != 0) goto exit_sha256_ex;

        /* Generate 2 (this is the actual test output) */
        ret = Hash_DRBG_Generate(drbg, output, outputSz,
                                 additionalB, additionalBSz);
    }

exit_sha256_ex:
    (void)Hash_DRBG_Uninstantiate(drbg);

#ifdef WOLFSSL_SMALL_STACK
    XFREE(drbg, heap, DYNAMIC_TYPE_RNG);
#endif

    return ret;
}
#endif /* !NO_SHA256 && !HAVE_SELFTEST && (!HAVE_FIPS || FIPS v7+) */


#ifdef WOLFSSL_DRBG_SHA512
/* Extended SHA-512 Hash_DRBG health test per SP 800-90A.
 * Supports flexible output sizes and prediction resistance mode.
 *
 * Per SP 800-90A Section 9.3.1, when prediction resistance is requested,
 * the additional_input is consumed by the Reseed step and the subsequent
 * Generate uses NULL additional_input.
 *
 * predResistance=0: Instantiate ->
 *                   Reseed(entropyB, additionalReseed) ->
 *                   Gen1(additionalA, discard) -> Gen2(additionalB, keep)
 * predResistance=1: Instantiate ->
 *                   Reseed(entropyB, additionalA)+Gen1(NULL, discard) ->
 *                   Reseed(entropyC, additionalB)+Gen2(NULL, keep)
 */
int wc_RNG_HealthTest_SHA512_ex2(
    int predResistance,
    const byte* nonce, word32 nonceSz,
    const byte* persoString, word32 persoStringSz,
    const byte* entropyA, word32 entropyASz,
    const byte* entropyB, word32 entropyBSz,
    const byte* entropyC, word32 entropyCsz,
    const byte* additionalA, word32 additionalASz,
    const byte* additionalB, word32 additionalBSz,
    const byte* additionalReseed, word32 additionalReseedSz,
    byte* output, word32 outputSz,
    void* heap, int devId)
{
    int ret;
    DRBG_SHA512_internal* drbg;
#ifndef WOLFSSL_SMALL_STACK
    DRBG_SHA512_internal  drbg_var;
#endif

    if (entropyA == NULL || output == NULL || outputSz == 0) {
        return BAD_FUNC_ARG;
    }

#ifdef WOLFSSL_SMALL_STACK
    drbg = (DRBG_SHA512_internal*)XMALLOC(sizeof(DRBG_SHA512_internal), heap,
        DYNAMIC_TYPE_RNG);
    if (drbg == NULL) {
        return MEMORY_E;
    }
#else
    drbg = &drbg_var;
#endif

    /* Instantiate with entropy, nonce, personalization string */
    ret = Hash512_DRBG_Instantiate(drbg, entropyA, entropyASz, nonce, nonceSz,
                                   persoString, persoStringSz, heap, devId);
    if (ret != 0) goto exit_sha512_ex2;

    if (predResistance) {
        /* Prediction resistance mode per SP 800-90A 9.3.1:
         * additional_input is passed to Reseed, Generate gets NULL */

        /* Reseed 1 with additionalA, then Generate 1 with NULL (discard) */
        if (entropyB != NULL && entropyBSz > 0) {
            ret = Hash512_DRBG_Reseed(drbg, entropyB, entropyBSz,
                                      additionalA, additionalASz);
            if (ret != 0) goto exit_sha512_ex2;
        }
        ret = Hash512_DRBG_Generate(drbg, output, outputSz, NULL, 0);
        if (ret != 0) goto exit_sha512_ex2;

        /* Reseed 2 with additionalB, then Generate 2 with NULL (keep) */
        if (entropyC != NULL && entropyCsz > 0) {
            ret = Hash512_DRBG_Reseed(drbg, entropyC, entropyCsz,
                                      additionalB, additionalBSz);
            if (ret != 0) goto exit_sha512_ex2;
        }
        ret = Hash512_DRBG_Generate(drbg, output, outputSz, NULL, 0);
    }
    else {
        /* Standard mode: explicit reseed, then two generates */
        if (entropyB != NULL && entropyBSz > 0) {
            ret = Hash512_DRBG_Reseed(drbg, entropyB, entropyBSz,
                                      additionalReseed, additionalReseedSz);
            if (ret != 0) goto exit_sha512_ex2;
        }

        /* Generate 1 (output discarded per NIST DRBGVS procedure) */
        ret = Hash512_DRBG_Generate(drbg, output, outputSz,
                                    additionalA, additionalASz);
        if (ret != 0) goto exit_sha512_ex2;

        /* Generate 2 (this is the actual test output) */
        ret = Hash512_DRBG_Generate(drbg, output, outputSz,
                                    additionalB, additionalBSz);
    }

exit_sha512_ex2:
    (void)Hash512_DRBG_Uninstantiate(drbg);

#ifdef WOLFSSL_SMALL_STACK
    XFREE(drbg, heap, DYNAMIC_TYPE_RNG);
#endif

    return (ret == DRBG_SUCCESS) ? 0 : -1;
}

#endif /* WOLFSSL_DRBG_SHA512 */

#endif /* HAVE_HASHDRBG */


#ifdef HAVE_WNR

/*
 * Init global Whitewood netRandom context
 * Returns 0 on success, negative on error
 */
int wc_InitNetRandom(const char* configFile, wnr_hmac_key hmac_cb, int timeout)
{
    int ret = 0;

    if (configFile == NULL || timeout < 0)
        return BAD_FUNC_ARG;

#ifndef WOLFSSL_MUTEX_INITIALIZER
    ret = wc_local_InitMutexOnce(&wnr_mutex, &wnr_mutex_inited);
    if (ret != 0) {
        WOLFSSL_MSG("Bad Init Mutex wnr_mutex");
        return ret;
    }
#endif

    if (wnr_inited > 0) {
        WOLFSSL_MSG("netRandom context already created, skipping");
        return 0;
    }

    if (wc_LockMutex(&wnr_mutex) != 0) {
        WOLFSSL_MSG("Bad Lock Mutex wnr_mutex");
        return BAD_MUTEX_E;
    }

    /* store entropy timeout */
    wnr_timeout = timeout;

    /* create global wnr_context struct */
    if (wnr_create(&wnr_ctx) != WNR_ERROR_NONE) {
        WOLFSSL_MSG("Error creating global netRandom context");
        ret = RNG_FAILURE_E;
        goto out;
    }

    /* load config file */
    if (wnr_config_loadf(wnr_ctx, (char*)configFile) != WNR_ERROR_NONE) {
        WOLFSSL_MSG("Error loading config file into netRandom context");
        wnr_destroy(wnr_ctx);
        wnr_ctx = NULL;
        ret = RNG_FAILURE_E;
        goto out;
    }

    /* create/init polling mechanism */
    if (wnr_poll_create() != WNR_ERROR_NONE) {
        WOLFSSL_MSG("Error initializing netRandom polling mechanism");
        wnr_destroy(wnr_ctx);
        wnr_ctx = NULL;
        ret = RNG_FAILURE_E;
        goto out;
    }

    /* validate config, set HMAC callback (optional) */
    if (wnr_setup(wnr_ctx, hmac_cb) != WNR_ERROR_NONE) {
        WOLFSSL_MSG("Error setting up netRandom context");
        wnr_destroy(wnr_ctx);
        wnr_ctx = NULL;
        wnr_poll_destroy();
        ret = RNG_FAILURE_E;
        goto out;
    }

    wnr_inited = 1;

out:

    wc_UnLockMutex(&wnr_mutex);

    return ret;
}

/*
 * Free global Whitewood netRandom context
 * Returns 0 on success, negative on error
 */
int wc_FreeNetRandom(void)
{
    if (wnr_inited > 0) {

        if (wc_LockMutex(&wnr_mutex) != 0) {
            WOLFSSL_MSG("Bad Lock Mutex wnr_mutex");
            return BAD_MUTEX_E;
        }

        if (wnr_ctx != NULL) {
            wnr_destroy(wnr_ctx);
            wnr_ctx = NULL;
        }
        wnr_poll_destroy();

        wc_UnLockMutex(&wnr_mutex);

#ifndef WOLFSSL_MUTEX_INITIALIZER
        wc_FreeMutex(&wnr_mutex);
        WOLFSSL_ATOMIC_STORE(wnr_mutex_inited, 0);
#endif

        wnr_inited = 0;
    }

    return 0;
}

#endif /* HAVE_WNR */


#if defined(HAVE_INTEL_RDRAND) || defined(HAVE_INTEL_RDSEED) || \
    defined(HAVE_AMD_RDSEED)

#ifdef WOLFSSL_ASYNC_CRYPT
    /* need more retries if multiple cores */
    #define INTELRD_RETRY (32 * 8)
#else
    #define INTELRD_RETRY 32
#endif

#if defined(HAVE_INTEL_RDSEED) || defined(HAVE_AMD_RDSEED)

#ifndef USE_INTEL_INTRINSICS

    /* return 0 on success */
    static WC_INLINE int IntelRDseed64(word64* seed)
    {
        unsigned char ok;

        __asm__ volatile("rdseed %0; setc %1":"=r"(*seed), "=qm"(ok));
        return (ok) ? 0 : -1;
    }

#else /* USE_INTEL_INTRINSICS */
    /* The compiler Visual Studio uses does not allow inline assembly.
     * It does allow for Intel intrinsic functions. */

    /* return 0 on success */
# ifdef __GNUC__
    __attribute__((target("rdseed")))
# endif
    static WC_INLINE int IntelRDseed64(word64* seed)
    {
        int ok;

        ok = _rdseed64_step((unsigned long long*) seed);
        return (ok) ? 0 : -1;
    }

#endif /* USE_INTEL_INTRINSICS */

/* return 0 on success */
static WC_INLINE int IntelRDseed64_r(word64* rnd)
{
    int i;
    for (i = 0; i < INTELRD_RETRY; i++) {
        if (IntelRDseed64(rnd) == 0)
            return 0;
    }
    return NOT_READY_E;
}

/* return 0 on success */
static int wc_GenerateSeed_IntelRD(OS_Seed* os, byte* output, word32 sz)
{
    int ret = 0;
    word64 rndTmp;
    static int rdseed_sanity_status = 0;
    word64 rndTmpLocal = 0;

    (void)os;

    if (!IS_INTEL_RDSEED(intel_flags))
        return WC_HW_E;

    /* Note, access to rdseed_sanity_status is benignly racey on multithreaded
     * targets.
     */
    if (rdseed_sanity_status == 0) {
        word64 sanity_word1 = 0, sanity_word2 = 0;

        ret = IntelRDseed64_r(&sanity_word1);
        if (ret != 0)
            return ret;

        ret = IntelRDseed64_r(&sanity_word2);
        if (ret != 0)
            return ret;

        if (sanity_word1 == sanity_word2) {
            ret = IntelRDseed64_r(&sanity_word1);
            if (ret != 0)
                return ret;

            if (sanity_word1 == sanity_word2) {
#ifdef WC_VERBOSE_RNG
                WOLFSSL_DEBUG_PRINTF(
                    "WARNING: disabling RDSEED due to repeating word 0x%lx -- "
                    "check CPU microcode version.", sanity_word2);
#endif
                rdseed_sanity_status = -1;
                return WC_HW_E;
            }
        }

        rdseed_sanity_status = 1;
    }
    else if (rdseed_sanity_status < 0) {
        return WC_HW_E;
    }

    for (; (sz / sizeof(word64)) > 0; sz -= sizeof(word64),
                                                output += sizeof(word64)) {
        ret = IntelRDseed64_r(&rndTmpLocal);
        if (ret != 0) {
            break;
        }
        writeUnalignedWord64(output, rndTmpLocal);
    }

    ForceZero(&rndTmpLocal, sizeof(rndTmpLocal));
    if (ret != 0) {
        return ret;
    }

    if (sz == 0)
        return 0;

    /* handle unaligned remainder */
    ret = IntelRDseed64_r(&rndTmp);
    if (ret != 0)
        return ret;

#ifdef WOLFSSL_CHECK_MEM_ZERO
    wc_MemZero_Add("wc_GenerateSeed rndTmp", &rndTmp, sizeof(rndTmp));
#endif
    XMEMCPY(output, &rndTmp, sz);
    ForceZero(&rndTmp, sizeof(rndTmp));
#ifdef WOLFSSL_CHECK_MEM_ZERO
    wc_MemZero_Check(&rndTmp, sizeof(rndTmp));
#endif

    return 0;
}

#endif /* HAVE_INTEL_RDSEED || HAVE_AMD_RDSEED */

#ifdef HAVE_INTEL_RDRAND

#ifndef USE_INTEL_INTRINSICS

/* return 0 on success */
static WC_INLINE int IntelRDrand64(word64 *rnd)
{
    unsigned char ok;

    __asm__ volatile("rdrand %0; setc %1":"=r"(*rnd), "=qm"(ok));

    return (ok) ? 0 : -1;
}

#else /* USE_INTEL_INTRINSICS */
    /* The compiler Visual Studio uses does not allow inline assembly.
     * It does allow for Intel intrinsic functions. */

/* return 0 on success */
# ifdef __GNUC__
__attribute__((target("rdrnd")))
# endif
static WC_INLINE int IntelRDrand64(word64 *rnd)
{
    int ok;

    ok = _rdrand64_step((unsigned long long*) rnd);

    return (ok) ? 0 : -1;
}

#endif /* USE_INTEL_INTRINSICS */

/* return 0 on success */
static WC_INLINE int IntelRDrand64_r(word64 *rnd)
{
    int i;
    for (i = 0; i < INTELRD_RETRY; i++) {
        if (IntelRDrand64(rnd) == 0)
            return 0;
    }
    return -1;
}

/* return 0 on success */
static int wc_GenerateRand_IntelRD(OS_Seed* os, byte* output, word32 sz)
{
    word64 rndTmp;
    int ret = 0;
    word64 rndTmpLocal = 0;

    (void)os;

    if (!IS_INTEL_RDRAND(intel_flags))
        return -1;

    for (; (sz / sizeof(word64)) > 0; sz -= sizeof(word64),
                                                output += sizeof(word64)) {
        ret = IntelRDrand64_r(&rndTmpLocal);
        if (ret != 0) {
            break;
        }
        writeUnalignedWord64(output, rndTmpLocal);
    }

    ForceZero(&rndTmpLocal, sizeof(rndTmpLocal));
    if (ret != 0) {
        return ret;
    }

    if (sz == 0)
        return 0;

    /* handle unaligned remainder */
    ret = IntelRDrand64_r(&rndTmp);
    if (ret != 0)
        return ret;

    XMEMCPY(output, &rndTmp, sz);
    ForceZero(&rndTmp, sizeof(rndTmp));

    return 0;
}

#endif /* HAVE_INTEL_RDRAND */
#endif /* HAVE_INTEL_RDRAND || HAVE_INTEL_RDSEED || HAVE_AMD_RDSEED */


#ifdef WOLFSSL_NOISE_SRC

/* Generic SP800-90B noise source.  Configuration struct and API:
 * wolfssl/wolfcrypt/random.h.
 *
 * Entropy model.  A port supplies raw, unconditioned octets through one
 * callback.  Each raw bit is credited hmin/100 bits of min-entropy, so a
 * full-entropy output octet needs 8 / (hmin/100) raw bits, and margin
 * oversamples on top of that; WC_NOISE_RAW_PER_SRC() turns the two into the
 * raw octets gathered per conditioner chunk.  Only source 0 is budgeted - any
 * further source is hashed in as defence in depth, and extra hash input can
 * never subtract entropy.
 *
 * Every gathered octet passes the 4.4.1 Repetition Count Test and the 4.4.2
 * Adaptive Proportion Test before reaching the conditioner, and _Init() runs
 * the 4.3 startup test over startupOctets per source first.  A failure is
 * latched: 4.3/4.4 want a persistent failure state, not a transparent retry,
 * because a source that trips and then passes is exactly what continuous
 * testing exists to catch.  Only _Free() clears it.
 *
 * Only test verdicts latch - the health tests and the _SelfTest() liveness
 * checks.  An error from the sample callback propagates unlatched and stays
 * retryable: it says the hardware did not answer, not that the noise is bad.
 * Either way no output is produced.
 *
 * Latching is also limited to the credited source.  Source 0 carries the whole
 * budget, so its failure fails closed.  Sources 1.. are unaccounted extra hash
 * input, and the cutoffs are derived for source 0's assumed min-entropy rather
 * than theirs, so one of them tripping is not evidence the seed is weak - it is
 * dropped for the life of the instance (recorded in src->degraded) and stops
 * contributing.  Output stays fully seeded because the budget never counted
 * it, and a source the budget ignores cannot deny service.
 *
 * Cutoffs belong to the caller and must match the assumed hmin, or they either
 * never trip or trip constantly.  For H bits of min-entropy per octet at
 * alpha = 2^-30: RCT C = 1 + ceil(30/H), APT C = 1 + CRITBINOM(W, 2^-H,
 * 1-alpha).
 *
 * No locking.  The instance is caller-owned state, so a port sharing one
 * across threads provides its own mutual exclusion. */

#ifdef NO_SHA256
    #error "WOLFSSL_NOISE_SRC conditions with SHA-256; do not set NO_SHA256"
#endif
#if WC_NOISE_CHUNK_SZ != WC_SHA256_DIGEST_SIZE
    #error "WC_NOISE_CHUNK_SZ must match WC_SHA256_DIGEST_SIZE"
#endif

/* len raw octets from one source.  No health testing - callers that keep the
 * data run NoiseSrc_HealthTest() over it. */
static int NoiseSrc_Gather(wc_NoiseSrc* src, byte* out, word32 len, int srcIdx)
{
    word32 i;
    int ret;

    for (i = 0; i < len; i++) {
        ret = src->sampleCb(src->ctx, srcIdx, &out[i]);
        if (ret != 0) {
            return ret;
        }
        /* The contract is raw octets, but where CHAR_BIT != 8 a callback can
         * legally leave bits above 0xFF in the cell.  Mask here so the
         * conditioner sees exactly what the health tests scored - they mask
         * already - and no high bits leak into the hash. */
        out[i] = WC_OCTET(out[i]);
    }

    return 0;
}

/* SP800-90B 4.4.1 RCT and 4.4.2 APT over every octet drawn from a source.
 * Returns at the offending sample so the rest of the buffer cannot scrub the
 * state that detected it, and latches the failure. */
static int NoiseSrc_HealthTest(wc_NoiseSrc* src, const byte* buf, word32 len,
                               int srcIdx)
{
    wc_NoiseHealth* st;
    word32 i;
    word16 s;

    if (srcIdx < 0 || srcIdx >= (int)src->numSrc) {
        return BAD_FUNC_ARG;
    }
    st = &src->health[srcIdx];

    for (i = 0; i < len; i++) {
        s = (word16)WC_OCTET(buf[i]);

        if (!st->started) {
            st->started  = 1;
            st->rctLast  = s;
            st->rctCount = 1;
            st->aptRef   = s;
            st->aptCount = 1;
            st->aptPos   = 1;
            continue;
        }

        if (s == st->rctLast) {
            st->rctCount++;
            if (st->rctCount >= src->rctCutoff) {
                if (srcIdx == 0) {
                    src->failed = ENTROPY_RT_E;
                }
                return ENTROPY_RT_E;
            }
        }
        else {
            st->rctLast  = s;
            st->rctCount = 1;
        }

        if (st->aptPos >= src->aptWindow) {
            st->aptRef   = s;
            st->aptCount = 1;
            st->aptPos   = 1;
        }
        else {
            if (s == st->aptRef) {
                st->aptCount++;
                if (st->aptCount >= src->aptCutoff) {
                    if (srcIdx == 0) {
                        src->failed = ENTROPY_APT_E;
                    }
                    return ENTROPY_APT_E;
                }
            }
            st->aptPos++;
        }
    }

    return 0;
}

int wc_NoiseSrc_Init(wc_NoiseSrc* src)
{
    word32 done;
    word32 take;
    word32 need;
    int i;
    int ret;

    if (src == NULL) {
        return BAD_FUNC_ARG;
    }
    if (src->failed != 0) {
        return src->failed;
    }
    if (src->inited) {
        return 0;
    }

    if (src->sampleCb == NULL || src->tag == NULL || src->work == NULL) {
        return BAD_FUNC_ARG;
    }
    if (src->numSrc < 1 || src->numSrc > WC_NOISE_SRC_MAX) {
        return BAD_FUNC_ARG;
    }
    if (src->hmin < 1 || src->hmin > 100 || src->margin < 1) {
        return BAD_FUNC_ARG;
    }
    if (src->rctCutoff < 2 || src->aptCutoff < 2 || src->aptWindow < 2) {
        return BAD_FUNC_ARG;
    }
    /* Below one APT window the startup pass never exercises that test. */
    if (src->startupOctets < (word32)src->aptWindow) {
        return BAD_FUNC_ARG;
    }

    src->rawPerSrc = WC_NOISE_RAW_PER_SRC(src->hmin, src->margin);
    need = src->rawPerSrc * (word32)src->numSrc;
    if (src->rawPerSrc == 0 || src->workSz < need) {
        return BUFFER_E;
    }

    XMEMSET(src->health, 0, sizeof(src->health));
    src->chunkCtr = 0;
    src->degraded = 0;

    /* SP800-90B 4.3: push startupOctets per source through the continuous
     * tests - more than one APT window - before releasing anything. */
    for (i = 0; i < (int)src->numSrc; i++) {
        for (done = 0; done < src->startupOctets; done += take) {
            take = src->startupOctets - done;
            if (take > src->rawPerSrc) {
                take = src->rawPerSrc;
            }
            /* Sampler errors and test verdicts are handled differently, so
             * keep them apart: a callback error means the hardware did not
             * answer and stays retryable for every source, while only a test
             * verdict drops or latches. */
            ret = NoiseSrc_Gather(src, src->work, take, i);
            if (ret != 0) {
                ForceZero(src->work, src->workSz);
                return ret;
            }
            ret = NoiseSrc_HealthTest(src, src->work, take, i);
            if (ret != 0) {
                if (i == 0) {
                    ForceZero(src->work, src->workSz);
                    return ret;   /* credited source: fail closed */
                }
                /* Uncredited: drop it and keep going - see the latch policy
                 * note at the top of this module. */
                src->degraded |= (word16)(1U << i);
                ret = 0;
                break;
            }
        }
    }

    ForceZero(src->work, src->workSz);
    src->inited = 1;
    return 0;
}

void wc_NoiseSrc_Free(wc_NoiseSrc* src)
{
    if (src == NULL) {
        return;
    }

    if (src->work != NULL && src->workSz > 0) {
        ForceZero(src->work, src->workSz);
    }
    XMEMSET(src->health, 0, sizeof(src->health));
    src->chunkCtr = 0;
    src->failed   = 0;
    src->degraded = 0;
    src->inited   = 0;
}

int wc_NoiseSrc_GetRaw(wc_NoiseSrc* src, byte* output, word32 len, int srcIdx)
{
    int ret;

    if (src == NULL || output == NULL) {
        return BAD_FUNC_ARG;
    }
    /* Before _Init(): numSrc is caller configuration, so a bad index need not
     * pay for the startup test or burn hardware entropy first. */
    if (srcIdx < 0 || srcIdx >= (int)src->numSrc) {
        return BAD_FUNC_ARG;
    }
    if (src->failed != 0) {
        return src->failed;
    }

    ret = wc_NoiseSrc_Init(src);
    if (ret != 0) {
        return ret;
    }

    ret = NoiseSrc_Gather(src, output, len, srcIdx);
    if (ret != 0) {
        ForceZero(output, len);
    }
    return ret;
}

int wc_NoiseSrc_GenerateSeed(wc_NoiseSrc* src, byte* output, word32 sz)
{
#ifdef WOLFSSL_SMALL_STACK
    wc_Sha256* sha = NULL;
#else
    wc_Sha256 sha[1];
#endif
    byte digest[WC_NOISE_CHUNK_SZ];
    byte ctrBuf[4];
    byte* raw;
    byte* outStart;
    word32 outLen;
    word32 take;
    word16 contributed;
    int i;
    int ret;

    if (src == NULL || output == NULL) {
        return BAD_FUNC_ARG;
    }
    if (sz == 0) {
        return 0;
    }
    if (src->failed != 0) {
        return src->failed;
    }

    /* Kept so a mid-way failure can wipe what already landed: no caller
     * should ever see a partially-filled seed buffer. */
    outStart = output;
    outLen   = sz;

    XMEMSET(digest, 0, sizeof(digest));

    ret = wc_NoiseSrc_Init(src);
    if (ret != 0) {
        return ret;
    }

#ifdef WOLFSSL_SMALL_STACK
    sha = (wc_Sha256*)XMALLOC(sizeof(wc_Sha256), NULL, DYNAMIC_TYPE_TMP_BUFFER);
    if (sha == NULL) {
        return MEMORY_E;
    }
#endif

    while (sz > 0) {
        contributed = 0;
        for (i = 0; i < (int)src->numSrc; i++) {
            if ((src->degraded & (word16)(1U << i)) != 0) {
                continue;   /* uncredited source already dropped */
            }
            raw = src->work + ((word32)i * src->rawPerSrc);

            /* A sampler error propagates for any source and is retryable;
             * only a health-test verdict drops or latches. */
            ret = NoiseSrc_Gather(src, raw, src->rawPerSrc, i);
            if (ret != 0) {
                goto out;
            }
            ret = NoiseSrc_HealthTest(src, raw, src->rawPerSrc, i);
            if (ret != 0) {
                if (i == 0) {
                    goto out;  /* fail closed; HealthTest latched src->failed */
                }
                src->degraded |= (word16)(1U << i);
                ret = 0;
                continue;
            }
            contributed |= (word16)(1U << i);
        }

        ret = wc_InitSha256(sha);
        if (ret != 0) {
            ForceZero(sha, sizeof(*sha));
            goto out;
        }

        src->chunkCtr++;
        ctrBuf[0] = WC_OCTET(src->chunkCtr >> 24);
        ctrBuf[1] = WC_OCTET(src->chunkCtr >> 16);
        ctrBuf[2] = WC_OCTET(src->chunkCtr >> 8);
        ctrBuf[3] = WC_OCTET(src->chunkCtr);

        ret = wc_Sha256Update(sha, (const byte*)src->tag,
                              (word32)XSTRLEN(src->tag));
        if (ret == 0) {
            ret = wc_Sha256Update(sha, ctrBuf, (word32)sizeof(ctrBuf));
        }
        for (i = 0; (ret == 0) && (i < (int)src->numSrc); i++) {
            if ((contributed & (word16)(1U << i)) == 0) {
                continue;   /* not gathered this chunk - never hash stale data */
            }
            raw = src->work + ((word32)i * src->rawPerSrc);
            ret = wc_Sha256Update(sha, raw, src->rawPerSrc);
        }
        if (ret == 0) {
            ret = wc_Sha256Final(sha, digest);
        }
        wc_Sha256Free(sha);
        ForceZero(sha, sizeof(*sha));
        if (ret != 0) {
            goto out;
        }

        take = (sz < (word32)WC_NOISE_CHUNK_SZ) ? sz
                                                : (word32)WC_NOISE_CHUNK_SZ;
        XMEMCPY(output, digest, take);
        output += take;
        sz -= take;
    }

out:
    if (ret != 0) {
        ForceZero(outStart, outLen);
    }
    ForceZero(digest, sizeof(digest));
    ForceZero(src->work, src->workSz);
#ifdef WOLFSSL_SMALL_STACK
    XFREE(sha, NULL, DYNAMIC_TYPE_TMP_BUFFER);
#endif
    return ret;
}

int wc_NoiseSrc_SelfTest(wc_NoiseSrc* src)
{
    /* Tests RAW noise, not conditioned seeds: the hashed chunk counter makes
     * two GenerateSeed() outputs differ even with every source dead. */
    byte* a;
    byte* b;
    word32 len;
    word32 i;
    byte diff;
    int s;
    int ret;

    if (src == NULL) {
        return BAD_FUNC_ARG;
    }

    ret = wc_NoiseSrc_Init(src);
    if (ret != 0) {
        return ret;
    }

    /* Two gathers side by side in the work buffer. */
    len = src->workSz / 2U;
    if (len > 64U) {
        len = 64U;
    }
    if (len == 0U) {
        return BUFFER_E;
    }
    a = src->work;
    b = src->work + len;

    for (s = 0; s < (int)src->numSrc; s++) {
        if ((src->degraded & (word16)(1U << s)) != 0) {
            continue;   /* already dropped - no point re-testing it */
        }
        ret = NoiseSrc_Gather(src, a, len, s);
        if (ret == 0) {
            ret = NoiseSrc_Gather(src, b, len, s);
        }
        if (ret != 0) {
            break;
        }

        /* A source stuck at any constant - including one whose clock was
         * never enabled - produces identical gathers. */
        /* ConstantCompare, not XMEMCMP: raw pre-conditioning samples. */
        if (ConstantCompare(a, b, (int)len) == 0) {
            ret = ENTROPY_RT_E;
            if (s == 0) {
                src->failed = ret;
                break;
            }
            src->degraded |= (word16)(1U << s);
            ret = 0;
            continue;
        }

        /* Constant-octet check, accumulated rather than early-exit. */
        diff = 0;
        for (i = 1; i < len; i++) {
            diff |= (byte)(a[i] ^ a[0]);
        }
        if (diff == 0) {
            ret = ENTROPY_RT_E;
            if (s == 0) {
                src->failed = ret;
                break;
            }
            src->degraded |= (word16)(1U << s);
            ret = 0;
            continue;
        }
    }

    /* A gather error above is deliberately not latched - see the policy note
     * at the top of this module. */
    ForceZero(src->work, src->workSz);

    return ret;
}

#endif /* WOLFSSL_NOISE_SRC */


/* Begin wc_GenerateSeed Implementations */
#if defined(CUSTOM_RAND_GENERATE_SEED)

    /* Implement your own random generation function
     * Return 0 to indicate success
     * int rand_gen_seed(byte* output, word32 sz);
     * #define CUSTOM_RAND_GENERATE_SEED  rand_gen_seed */

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        (void)os; /* Suppress unused arg warning */
        return CUSTOM_RAND_GENERATE_SEED(output, sz);
    }

#elif defined(CUSTOM_RAND_GENERATE_SEED_OS)

    /* Implement your own random generation function,
     *  which includes OS_Seed.
     * Return 0 to indicate success
     * int rand_gen_seed(OS_Seed* os, byte* output, word32 sz);
     * #define CUSTOM_RAND_GENERATE_SEED_OS  rand_gen_seed */

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        return CUSTOM_RAND_GENERATE_SEED_OS(os, output, sz);
    }

#elif defined(CUSTOM_RAND_GENERATE)

   /* Implement your own random generation function
    * word32 rand_gen(void);
    * #define CUSTOM_RAND_GENERATE  rand_gen  */

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        word32 i = 0;

        (void)os;

        while (i < sz)
        {
            /* If not aligned or there is odd/remainder */
            if( (i + sizeof(CUSTOM_RAND_TYPE)) > sz ||
                ((wc_ptr_t)&output[i] % sizeof(CUSTOM_RAND_TYPE)) != 0
            ) {
                /* Single byte at a time */
                output[i++] = (byte)CUSTOM_RAND_GENERATE();
            }
            else {
                /* Use native 8, 16, 32 or 64 copy instruction */
                *((CUSTOM_RAND_TYPE*)&output[i]) = CUSTOM_RAND_GENERATE();
                i += sizeof(CUSTOM_RAND_TYPE);
            }
        }

        return 0;
    }

#elif defined(WOLFSSL_SGX)

int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
{
    int ret = !SGX_SUCCESS;
    int i, read_max = 10;

    for (i = 0; i < read_max && ret != SGX_SUCCESS; i++) {
        ret = sgx_read_rand(output, sz);
    }

    (void)os;
    return (ret == SGX_SUCCESS) ? 0 : 1;
}

#elif defined(USE_WINDOWS_API)

#ifdef WIN_REUSE_CRYPT_HANDLE
/* shared crypt handle for RNG use */
static ProviderHandle gHandle = 0;

int wc_WinCryptHandleInit(void)
{
    int ret = 0;
    if (gHandle == 0) {
        if(!CryptAcquireContext(&gHandle, 0, 0, PROV_RSA_FULL,
                                        CRYPT_VERIFYCONTEXT)) {
            DWORD dw = GetLastError();
            WOLFSSL_MSG("CryptAcquireContext failed!");
            WOLFSSL_ERROR((int)dw);
            ret = WINCRYPT_E;
        }
    }
    return ret;
}

void wc_WinCryptHandleCleanup(void)
{
    if (gHandle != 0) {
        CryptReleaseContext(gHandle, 0);
        gHandle = 0;
    }
}
#endif /* WIN_REUSE_CRYPT_HANDLE */

int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
{
#ifdef WOLF_CRYPTO_CB
    int ret;

    if (os != NULL
    #ifndef WOLF_CRYPTO_CB_FIND
        && os->devId != INVALID_DEVID)
    #endif
    {
        ret = wc_CryptoCb_RandomSeed(os, output, sz);
        if (ret != WC_NO_ERR_TRACE(CRYPTOCB_UNAVAILABLE))
            return ret;
        /* fall-through when unavailable */
    }
#endif

    #if defined(HAVE_INTEL_RDSEED) || defined(HAVE_AMD_RDSEED)
        if (IS_INTEL_RDSEED(intel_flags)) {
             if (!wc_GenerateSeed_IntelRD(NULL, output, sz)) {
                 /* success, we're done */
                 return 0;
             }
        #ifdef FORCE_FAILURE_RDSEED
             /* don't fall back to CryptoAPI */
             return READ_RAN_E;
        #endif
        }
    #ifdef FORCE_FAILURE_RDSEED
        else {
            /* Don't fall back to system randomness */
            return MISSING_RNG_E;
        }
    #endif
    #endif /* HAVE_INTEL_RDSEED || HAVE_AMD_RDSEED */

#ifdef WIN_REUSE_CRYPT_HANDLE
    /* Check that handle was initialized.
     * Note: initialization should be done through:
     * wolfSSL_Init -> wolfCrypt_Init -> wc_WinCryptHandleInit
     */
    if (wc_WinCryptHandleInit() != 0) {
        return WINCRYPT_E;
    }
    if (!CryptGenRandom(gHandle, sz, output))
        return CRYPTGEN_E;
#else
    if (!CryptAcquireContext(&os->handle, 0, 0, PROV_RSA_FULL,
                            CRYPT_VERIFYCONTEXT)) {
        return WINCRYPT_E;
    }
    if (!CryptGenRandom(os->handle, sz, output)) {
        return CRYPTGEN_E;
    }
    CryptReleaseContext(os->handle, 0);
    os->handle = 0;
#endif

    return 0;
}


#elif defined(HAVE_RTP_SYS) || defined(EBSNET)

#include "rtprand.h"   /* rtp_rand () */

#if (defined(HAVE_RTP_SYS) || (defined(RTPLATFORM) && (RTPLATFORM != 0)))
#include "rtptime.h"   /* rtp_get_system_msec() */

int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
{
    word32 i;

    rtp_srand(rtp_get_system_msec());
    for (i = 0; i < sz; i++ ) {
        output[i] = rtp_rand() % 256;
    }

    return 0;
}
#else
int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
{
    word32 i;
    KS_SEED(ks_get_ticks());

    for (i = 0; i < sz; i++ ) {
        output[i] = KS_RANDOM() % 256;
    }

    return 0;
}
#endif /* defined(HAVE_RTP_SYS) || (defined(RTPLATFORM) && (RTPLATFORM != 0)) */

#elif (defined(WOLFSSL_ATMEL) || defined(WOLFSSL_ATECC_RNG)) && \
      !defined(WOLFSSL_PIC32MZ_RNG)
    /* enable ATECC RNG unless using PIC32MZ one instead */
    #include <wolfssl/wolfcrypt/port/atmel/atmel.h>

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        int ret = 0;

        (void)os;
        if (output == NULL) {
            return BUFFER_E;
        }

        ret = atmel_get_random_number(sz, output);

        return ret;
    }

#elif defined(MICROCHIP_PIC32) || defined(MICROCHIP_MPLAB_HARMONY)

    #ifdef MICROCHIP_MPLAB_HARMONY
        #ifdef MICROCHIP_MPLAB_HARMONY_3
            #include "system/time/sys_time.h"
            #define PIC32_SEED_COUNT SYS_TIME_CounterGet
        #else
            #define PIC32_SEED_COUNT _CP0_GET_COUNT
        #endif
    #else
        #if !defined(WOLFSSL_MICROCHIP_PIC32MZ)
            #include <peripheral/timer.h>
        #endif
        extern word32 ReadCoreTimer(void);
        #define PIC32_SEED_COUNT ReadCoreTimer
    #endif

    #ifdef WOLFSSL_PIC32MZ_RNG
        #include "xc.h"
        int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
        {
            int i;
            byte rnd[8];
            word32 *rnd32 = (word32 *)rnd;
            word32 size = sz;
            byte* op = output;

#if ((__PIC32_FEATURE_SET0 == 'E') && (__PIC32_FEATURE_SET1 == 'C'))
            RNGNUMGEN1 = _CP0_GET_COUNT();
            RNGPOLY1 = _CP0_GET_COUNT();
            RNGPOLY2 = _CP0_GET_COUNT();
            RNGNUMGEN2 = _CP0_GET_COUNT();
#else
            /* All others can be seeded from the TRNG */
            RNGCONbits.TRNGMODE = 1;
            RNGCONbits.TRNGEN = 1;
            while (RNGCNT < 64);
            RNGCONbits.LOAD = 1;
            while (RNGCONbits.LOAD == 1);
            while (RNGCNT < 64);
            RNGPOLY2 = RNGSEED2;
            RNGPOLY1 = RNGSEED1;
#endif

            RNGCONbits.PLEN = 0x40;
            RNGCONbits.PRNGEN = 1;
            for (i=0; i<5; i++) { /* wait for RNGNUMGEN ready */
                volatile int x, y;
                x = RNGNUMGEN1;
                y = RNGNUMGEN2;
                (void)x;
                (void)y;
            }
            do {
                rnd32[0] = RNGNUMGEN1;
                rnd32[1] = RNGNUMGEN2;

                for(i=0; i<8; i++, op++) {
                    *op = rnd[i];
                    size --;
                    if(size==0)break;
                }
            } while(size);
            return 0;
        }
    #else  /* WOLFSSL_PIC32MZ_RNG */
        /* uses the core timer, in nanoseconds to seed srand */
        int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
        {
            int i;
            srand(PIC32_SEED_COUNT() * 25);

            for (i = 0; i < sz; i++ ) {
                output[i] = rand() % 256;
                if ( (i % 8) == 7)
                    srand(PIC32_SEED_COUNT() * 25);
            }
            return 0;
        }
    #endif /* WOLFSSL_PIC32MZ_RNG */

#elif defined(FREESCALE_K70_RNGA) || defined(FREESCALE_RNGA)
    /*
     * wc_Generates a RNG seed using the Random Number Generator Accelerator
     * on the Kinetis K70. Documentation located in Chapter 37 of
     * K70 Sub-Family Reference Manual (see Note 3 in the README for link).
     */
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        word32 i;

        /* turn on RNGA module */
        #if defined(SIM_SCGC3_RNGA_MASK)
            SIM_SCGC3 |= SIM_SCGC3_RNGA_MASK;
        #endif
        #if defined(SIM_SCGC6_RNGA_MASK)
            /* additionally needed for at least K64F */
            SIM_SCGC6 |= SIM_SCGC6_RNGA_MASK;
        #endif

        /* set SLP bit to 0 - "RNGA is not in sleep mode" */
        RNG_CR &= ~RNG_CR_SLP_MASK;

        /* set HA bit to 1 - "security violations masked" */
        RNG_CR |= RNG_CR_HA_MASK;

        /* set GO bit to 1 - "output register loaded with data" */
        RNG_CR |= RNG_CR_GO_MASK;

        for (i = 0; i < sz; i++) {

            /* wait for RNG FIFO to be full */
            while((RNG_SR & RNG_SR_OREG_LVL(0xF)) == 0) {}

            /* get value */
            output[i] = RNG_OR;
        }

        return 0;
    }

#elif defined(FREESCALE_K53_RNGB) || defined(FREESCALE_RNGB)
    /*
     * wc_Generates a RNG seed using the Random Number Generator (RNGB)
     * on the Kinetis K53. Documentation located in Chapter 33 of
     * K53 Sub-Family Reference Manual (see note in the README for link).
     */
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        int i;

        /* turn on RNGB module */
        SIM_SCGC3 |= SIM_SCGC3_RNGB_MASK;

        /* reset RNGB */
        RNG_CMD |= RNG_CMD_SR_MASK;

        /* FIFO generate interrupt, return all zeros on underflow,
         * set auto reseed */
        RNG_CR |= (RNG_CR_FUFMOD_MASK | RNG_CR_AR_MASK);

        /* gen seed, clear interrupts, clear errors */
        RNG_CMD |= (RNG_CMD_GS_MASK | RNG_CMD_CI_MASK | RNG_CMD_CE_MASK);

        /* wait for seeding to complete */
        while ((RNG_SR & RNG_SR_SDN_MASK) == 0) {}

        for (i = 0; i < sz; i++) {

            /* wait for a word to be available from FIFO */
            while((RNG_SR & RNG_SR_FIFO_LVL_MASK) == 0) {}

            /* get value */
            output[i] = RNG_OUT;
        }

        return 0;
    }

#elif defined(FREESCALE_KSDK_2_0_TRNG)
    #ifndef TRNG0
    #define TRNG0 TRNG
    #endif

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        status_t status;
        status = TRNG_GetRandomData(TRNG0, output, sz);
        (void)os;
        if (status == kStatus_Success)
        {
            return(0);
        }
        return RAN_BLOCK_E;
    }

#elif defined(FREESCALE_KSDK_2_0_RNGA)

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        status_t status;
        status = RNGA_GetRandomData(RNG, output, sz);
        (void)os;
        if (status == kStatus_Success)
        {
            return(0);
        }
        return RAN_BLOCK_E;
    }


#elif defined(FREESCALE_RNGA)

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        status_t status;
        status = RNGA_GetRandomData(RNG, output, sz);
        (void)os;
        if (status == kStatus_Success)
        {
            return(0);
        }
        return RAN_BLOCK_E;
    }
#elif !defined(WOLFSSL_CAAM) && \
    (defined(FREESCALE_MQX) || defined(FREESCALE_KSDK_MQX) || \
     defined(FREESCALE_KSDK_BM) || defined(FREESCALE_FREE_RTOS))
    /*
     * Fallback to USE_TEST_GENSEED if a FREESCALE platform did not match any
     * of the TRNG/RNGA/RNGB support
     */
    #define USE_TEST_GENSEED

#elif defined(WOLFSSL_SILABS_SE_ACCEL)
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        (void)os;
        return silabs_GenerateRand(output, sz);
    }

#elif defined(STM32_RNG)
     /* Generate a RNG seed using the hardware random number generator
      * on the STM32F2/F4/F7/L4. */
    #include <wolfssl/wolfcrypt/port/st/stm32.h>
        /* Pulls in WC_STM32_RNG_CLK_ENABLE for WOLFSSL_STM32_BARE builds */
    #ifdef WC_STM32_RNG_DIAG
        /* The WC_STM32_RNG_DIAG paths below use printf(); pull in stdio.h so the
         * file compiles on strict C99+ toolchains when diagnostics are enabled. */
        #include <stdio.h>
    #endif


    #ifdef WOLFSSL_STM32_CUBEMX
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        int ret;
        RNG_HandleTypeDef hrng;
        word32 i = 0;
        (void)os;

        ret = wolfSSL_CryptHwMutexLock();
        if (ret != 0) {
            return ret;
        }

        /* enable RNG clock source */
        __HAL_RCC_RNG_CLK_ENABLE();

        /* enable RNG peripheral */
        XMEMSET(&hrng, 0, sizeof(hrng));
        hrng.Instance = RNG;
        HAL_RNG_Init(&hrng);

        while (i < sz) {
            /* If not aligned or there is odd/remainder */
            if( (i + sizeof(word32)) > sz ||
                ((wc_ptr_t)&output[i] % sizeof(word32)) != 0
            ) {
                /* Single byte at a time */
                uint32_t tmpRng = 0;
                if (HAL_RNG_GenerateRandomNumber(&hrng, &tmpRng) != HAL_OK) {
                    wolfSSL_CryptHwMutexUnLock();
                    return RAN_BLOCK_E;
                }
                output[i++] = (byte)tmpRng;
            }
            else {
                /* Use native 32 instruction */
                if (HAL_RNG_GenerateRandomNumber(&hrng, (uint32_t*)&output[i]) != HAL_OK) {
                    wolfSSL_CryptHwMutexUnLock();
                    return RAN_BLOCK_E;
                }
                i += sizeof(word32);
            }
        }

        HAL_RNG_DeInit(&hrng);

        wolfSSL_CryptHwMutexUnLock();

        return 0;
    }
    #elif defined(WOLFSSL_STM32F427_RNG) || defined(WOLFSSL_STM32_RNG_NOLIB) \
        || defined(STM32_NUTTX_RNG)

    #ifdef STM32_NUTTX_RNG
        #include "hardware/stm32_rng.h"
        /* Set CONFIG_STM32U5_RNG in NuttX to enable the RCC */
        #define WC_RNG_CR *((volatile uint32_t*)(STM32_RNG_CR))
        #define WC_RNG_SR *((volatile uint32_t*)(STM32_RNG_SR))
        #define WC_RNG_DR *((volatile uint32_t*)(STM32_RNG_DR))
    #else
        /* Comes from "stm32xxxx_hal.h" */
        #define WC_RNG_CR RNG->CR
        #define WC_RNG_SR RNG->SR
        #define WC_RNG_DR RNG->DR
    #endif


    /* Bounded poll for DRDY, plus recovery from SECS / CECS. The
     * unbounded `while (DRDY == 0)` loop in the original code spins
     * forever on chips where the RNG kernel clock is unstable
     * (e.g. WL55 with RNGSEL = MSI under sustained ECDSA-key-gen
     * load), because once the IP latches a Seed-error or Clock-
     * error condition it stops asserting DRDY. Per the STM32 RM
     * recovery sequence: clear SEIS/CEIS, toggle RNGEN, discard the
     * stale words sitting in the RNG output, then retry. */
    #ifndef STM32_BARE_RNG_BYTE_TIMEOUT
        #define STM32_BARE_RNG_BYTE_TIMEOUT 0x40000
    #endif
    #ifndef STM32_BARE_RNG_MAX_RETRIES
        #define STM32_BARE_RNG_MAX_RETRIES 8
    #endif

    /* Bring the direct-register RNG to a producing state: clock enable, the
     * new-gen (C5) NIST conditioning under CONDRST on the first call, and
     * RNGEN. Mutex-free -- the caller must already hold the crypto HW mutex.
     * Shared by wc_GenerateSeed (below) and the SAES self-init path
     * (Stm32SaesEnsureRng), so a cold DHUK/SAES operation no longer requires a
     * prior wc_InitRng. Returns 0, or RNG_FAILURE_E if the conditioning
     * soft-reset never clears. */
    WOLFSSL_LOCAL int wc_stm32_rng_ensure_ready(void)
    {
        word32 t = 0;
        (void)t;

    #ifndef STM32_NUTTX_RNG
        /* enable RNG peripheral clock */
        #ifdef WC_STM32_RNG_CLK_ENABLE
            WC_STM32_RNG_CLK_ENABLE();
        #else
            /* Default for F4/F7/L4/L5/U5/H5/H7 -- RNG on AHB2 */
            RCC->AHB2ENR |= RCC_AHB2ENR_RNGEN;
        #endif
    #endif

        /* On the new-gen STM32C5 RNG IP the CR register is locked at
         * reset (CONFIGLOCK clear, but the IP refuses to produce data
         * until a NIST-compliant CONFIG1/2/3 + NSCR + HTCR sequence
         * has been written under CONDRST). The HAL ships canonical
         * candidate values in the device header (RNG_CAND_NIST_*).
         * Detect the family by presence of that symbol -- on chips
         * without it (F4/F7/L4/U5/H7/H5/WL/etc.) skip. Do this only
         * on the first call (RNGEN clear) so subsequent calls don't
         * disturb a running peripheral. */
    #if defined(RNG_CAND_NIST_CR_VALUE) && defined(RNG_CR_CONDRST) && \
        !defined(WC_STM32_RNG_NO_NIST_INIT)
        if ((WC_RNG_CR & RNG_CR_RNGEN) == 0U) {
        #ifdef RNG_SR_BUSY
            /* HAL flow: drain BUSY before writing CR. */
            t = 0;
            while ((WC_RNG_SR & RNG_SR_BUSY) != 0U) {
                if (++t >= STM32_BARE_RNG_BYTE_TIMEOUT) {
                    break;
                }
            }
        #endif
            WC_RNG_CR = (uint32_t)RNG_CAND_NIST_CR_VALUE |
                        (uint32_t)RNG_CR_CONDRST;
        #ifdef RNG_CAND_NIST_NSCR_VALUE
            RNG->NSCR = (uint32_t)RNG_CAND_NIST_NSCR_VALUE;
        #endif
        #ifdef RNG_CAND_NIST_HTCR_VALUE
            RNG->HTCR[0] = (uint32_t)RNG_CAND_NIST_HTCR_VALUE;
        #endif
            /* Clear CONDRST and wait for the IP to mirror it back. The
             * STM32 HAL polls RNG_CR.CONDRST (not SR.BUSY) for completion
             * of the conditioning soft-reset; SR.BUSY drops earlier in
             * the seed-pull pipeline on at least the C5 IP and reading
             * it as "conditioning done" trips a SECS=1 a few microseconds
             * later when RNGEN goes high. Bounded so a misconfigured
             * kernel clock returns a clean error instead of hanging. */
            WC_RNG_CR &= ~(uint32_t)RNG_CR_CONDRST;
            t = 0;
            while ((WC_RNG_CR & RNG_CR_CONDRST) != 0U) {
                if (++t >= STM32_BARE_RNG_BYTE_TIMEOUT) {
#ifdef WC_STM32_RNG_DIAG
                    printf("[RNG] CONDRST stuck CR=%08lx SR=%08lx\n",
                           (unsigned long)WC_RNG_CR,
                           (unsigned long)WC_RNG_SR);
#endif
                    return RNG_FAILURE_E;
                }
            }
#ifdef WC_STM32_RNG_DIAG
            printf("[RNG] post-NIST CR=%08lx SR=%08lx t=%lu\n",
                   (unsigned long)WC_RNG_CR,
                   (unsigned long)WC_RNG_SR,
                   (unsigned long)t);
#endif
        }
    #endif

        /* enable RNG interrupt, set IE bit in RNG->CR register */
        WC_RNG_CR |= RNG_CR_IE;

        /* enable RNG, set RNGEN bit in RNG->CR. Activates RNG,
         * RNG_LFSR, and error detector. WC_STM32_RNG_CED_DISABLE
         * additionally sets CR.CED=1 to suppress the clock-error
         * detection -- the Linux STM32 RNG driver does this and on
         * the C5 silicon the CED detector trips on a (perfectly fine)
         * 48 MHz kernel clock for reasons unclear in the RM. */
#ifdef WC_STM32_RNG_CED_DISABLE
        WC_RNG_CR |= RNG_CR_RNGEN | RNG_CR_CED;
#else
        WC_RNG_CR |= RNG_CR_RNGEN;
#endif

        return 0;
    }

    /* Generate a RNG seed using the hardware RNG on the STM32F427
     * directly, following steps outlined in STM32F4 Reference
     * Manual (Chapter 24) for STM32F4xx family. */
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        int ret;
        word32 i;
        word32 t;
        word32 guard;
        word32 retries;
        word32 sr;
        (void)os;

        ret = wolfSSL_CryptHwMutexLock();
        if (ret != 0) {
            return ret;
        }

        /* Clock enable + (C5) NIST conditioning + RNGEN, shared with the SAES
         * self-init path. Mutex-free helper; we hold the mutex. */
        ret = wc_stm32_rng_ensure_ready();
        if (ret != 0) {
            wolfSSL_CryptHwMutexUnLock();
            return ret;
        }

        /* (No early SECS/CECS bail here.) The HAL doesn't check error
         * status immediately after RNGEN -- the IP needs a few cycles
         * after enable for the first seed pull, and a transient SEIS/SECS
         * can latch and resolve itself through the auto-reset that the
         * retry loop below already handles. Bailing here returned
         * RNG_FAILURE_E (-199) on first-init on the STM32C5 silicon.
         * NOTE: this branch serves all direct-register STM32 RNG users
         * (WOLFSSL_STM32F427_RNG / WOLFSSL_STM32_RNG_NOLIB / STM32_NUTTX_RNG),
         * not only the BARE/C5 port, so this bounded-retry + recovery applies
         * to every NOLIB family. It is strictly more robust than the old early
         * fast-fail: it still returns RNG_FAILURE_E after the retry budget. */

        for (i = 0; i < sz; i++) {
            retries = 0;
            for (;;) {
                t = 0;
                /* Sample SR once before the loop so the post-loop
                 * happy-path / error checks have a defined value even
                 * if STM32_BARE_RNG_BYTE_TIMEOUT is configured to 0. */
                sr = WC_RNG_SR;
                /* Bounded DRDY poll -- breaks on either DRDY or any
                 * error indication (SECS/CECS). */
                while (t < STM32_BARE_RNG_BYTE_TIMEOUT) {
                    sr = WC_RNG_SR;
                    if ((sr & (RNG_SR_DRDY | RNG_SR_SECS |
                               RNG_SR_CECS)) != 0U) {
                        break;
                    }
                    t++;
                }

                /* Happy path: data ready and no error. */
                if ((sr & RNG_SR_DRDY) != 0U &&
                    (sr & (RNG_SR_SECS | RNG_SR_CECS)) == 0U) {
                    output[i] = WC_RNG_DR;
                    break;
                }

                /* Either timed out or an error latched. Recover. */
                if (++retries > STM32_BARE_RNG_MAX_RETRIES) {
#ifdef WC_STM32_RNG_DIAG
                    printf("[RNG] retry max byte=%lu sr=%08lx CR=%08lx\n",
                           (unsigned long)i,
                           (unsigned long)sr,
                           (unsigned long)WC_RNG_CR);
#endif
                    wolfSSL_CryptHwMutexUnLock();
                    return RNG_FAILURE_E;
                }
#ifdef WC_STM32_RNG_DIAG
                printf("[RNG] retry byte=%lu retries=%lu sr=%08lx\n",
                       (unsigned long)i,
                       (unsigned long)retries,
                       (unsigned long)sr);
#endif

                /* Recovery sequence (per STM32 RM RNG chapter):
                 *   1. Clear SEIS / CEIS interrupt status by writing 0
                 *      to those bits. All other SR bits are read-only
                 *      status indicators (DRDY / BUSY / SECS / CECS);
                 *      writing 0 to them has no effect per the RM, so
                 *      a plain 0 write is safe and avoids the
                 *      read-modify-write hitting any reserved bits the
                 *      IP revision may add later.
                 *   2. Toggle RNGEN off then on to drop any stale
                 *      LFSR state that may be tainted by the error.
                 *   3. Discard four DR reads to flush the pipeline
                 *      (only meaningful when DRDY is set; otherwise
                 *      the reads are harmless and bounded). The 'guard'
                 *      counter bounds the loop independently of 't' so a
                 *      marginal kernel clock (DRDY stays 0, no error
                 *      latched) cannot spin forever -- it falls through
                 *      to the outer retry/backoff instead of hanging. */
                WC_RNG_SR = 0;
                WC_RNG_CR &= ~RNG_CR_RNGEN;
                WC_RNG_CR |= RNG_CR_RNGEN;
                t = 0;
                guard = 0;
                while (t < 4U && guard < STM32_BARE_RNG_BYTE_TIMEOUT) {
                    guard++;
                    if ((WC_RNG_SR & RNG_SR_DRDY) != 0U) {
                        (void)WC_RNG_DR;
                        t++;
                    }
                    else if ((WC_RNG_SR &
                              (RNG_SR_SECS | RNG_SR_CECS)) != 0U) {
                        /* Clock-error during recovery -- bail and
                         * let the outer retry handle it. */
                        break;
                    }
                }
            }
        }

        wolfSSL_CryptHwMutexUnLock();

        return 0;
    }

    #else

    /* Generate a RNG seed using the STM32 Standard Peripheral Library */
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        int ret;
        word32 i;
        (void)os;

        ret = wolfSSL_CryptHwMutexLock();
        if (ret != 0) {
            return ret;
        }

        /* enable RNG clock source */
        RCC_AHB2PeriphClockCmd(RCC_AHB2Periph_RNG, ENABLE);

        /* reset RNG */
        RNG_DeInit();

        /* enable RNG peripheral */
        RNG_Cmd(ENABLE);

        /* verify no errors with RNG_CLK or Seed */
        if (RNG_GetFlagStatus(RNG_FLAG_SECS | RNG_FLAG_CECS) != RESET) {
            wolfSSL_CryptHwMutexUnLock();
            return RNG_FAILURE_E;
        }

        for (i = 0; i < sz; i++) {
            /* wait until RNG number is ready */
            while (RNG_GetFlagStatus(RNG_FLAG_DRDY) == RESET) { }

            /* get value */
            output[i] = RNG_GetRandomNumber();
        }

        wolfSSL_CryptHwMutexUnLock();

        return 0;
    }
    #endif /* WOLFSSL_STM32_CUBEMX */

#elif defined(WOLFSSL_TIRTOS)
    #warning "potential for not enough entropy, currently being used for testing"
    #include <xdc/runtime/Timestamp.h>
    #include <stdlib.h>
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        int i;
        srand(xdc_runtime_Timestamp_get32());

        for (i = 0; i < sz; i++ ) {
            output[i] = rand() % 256;
            if ((i % 8) == 7) {
                srand(xdc_runtime_Timestamp_get32());
            }
        }

        return 0;
    }

#elif defined(WOLFSSL_PB)

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        word32 i;
        for (i = 0; i < sz; i++)
            output[i] = UTL_Rand();

        (void)os;

        return 0;
    }

#elif defined(WOLFSSL_NUCLEUS)
#include "nucleus.h"
#include "kernel/plus_common.h"

#warning "potential for not enough entropy, currently being used for testing"
int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
{
    int i;
    srand(NU_Get_Time_Stamp());

    for (i = 0; i < sz; i++ ) {
        output[i] = rand() % 256;
        if ((i % 8) == 7) {
            srand(NU_Get_Time_Stamp());
        }
    }

    return 0;
}
#elif defined(WOLFSSL_DEOS) && !defined(CUSTOM_RAND_GENERATE)
    #include "stdlib.h"

    #warning "potential for not enough entropy, currently being used for testing Deos"
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        int i;
        int seed = XTIME(0);
        (void)os;

        for (i = 0; i < sz; i++ ) {
            output[i] = rand_r(&seed) % 256;
            if ((i % 8) == 7) {
                seed = XTIME(0);
                rand_r(&seed);
            }
        }

        return 0;
    }
#elif defined(WOLFSSL_VXWORKS)
    #ifdef WOLFSSL_VXWORKS_6_x
        #include "stdlib.h"
        #warning "potential for not enough entropy, currently being used for testing"
        int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
        {
            int i;
            unsigned int seed = (unsigned int)XTIME(0);
            (void)os;

            for (i = 0; i < sz; i++ ) {
                output[i] = rand_r(&seed) % 256;
                if ((i % 8) == 7) {
                    seed = (unsigned int)XTIME(0);
                    rand_r(&seed);
                }
            }

            return 0;
        }
    #else
        #include <randomNumGen.h>
        #include <tickLib.h>

        int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz) {
            STATUS                status   = ERROR;
            RANDOM_NUM_GEN_STATUS r_status = RANDOM_NUM_GEN_ERROR;
            _Vx_ticks_t           seed = 0;

            #ifdef VXWORKS_SIM
                /* cannot generate true entropy with VxWorks simulator */
                #warning "not enough entropy, simulator for testing only"
                int i = 0;

                for (i = 0; i < 1000; i++) {
                    randomAddTimeStamp();
                }
            #endif

            /*
              wolfSSL can request 52 Bytes of random bytes. We need to add
              buffer to the entropy pool to ensure we can get more than 32 Bytes.
              Because VxWorks has entropy limits (ENTROPY_MIN and ENTROPY_MAX)
              defined as 256 and 1024 bits, see randomSWNumGenLib.c.

              randStatus() can return the following status:
              RANDOM_NUM_GEN_NO_ENTROPY when entropy is 0
              RANDOM_NUM_GEN_ERROR, entropy is not initialized
              RANDOM_NUM_GEN_NOT_ENOUGH_ENTROPY if entropy < 32 Bytes
              RANDOM_NUM_GEN_ENOUGH_ENTROPY if entropy is between 32 and 128 Bytes
              RANDOM_NUM_GEN_MAX_ENTROPY if entropy is greater than 128 Bytes
            */

            do {
                seed = tickGet();
                status = randAdd(&seed, sizeof(_Vx_ticks_t), 2);
                if (status == OK)
                    r_status = randStatus();

            } while (r_status != RANDOM_NUM_GEN_MAX_ENTROPY &&
                     r_status != RANDOM_NUM_GEN_ERROR && status == OK);

            if (r_status == RANDOM_NUM_GEN_ERROR)
                return RNG_FAILURE_E;

            status = randBytes (output, sz);

            if (status == ERROR) {
                return RNG_FAILURE_E;
            }

            return 0;
        }
    #endif
#elif defined(WOLFSSL_NRF51) || defined(WOLFSSL_NRF5x)
    #include "app_error.h"
    #include "nrf_drv_rng.h"
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        int remaining = sz, pos = 0;
        word32 err_code;
        byte available;
        static byte initialized = 0;

        (void)os;

        /* Make sure RNG is running */
        if (!initialized) {
            err_code = nrf_drv_rng_init(NULL);
            if (err_code != NRF_SUCCESS && err_code != NRF_ERROR_INVALID_STATE
            #ifdef NRF_ERROR_MODULE_ALREADY_INITIALIZED
                && err_code != NRF_ERROR_MODULE_ALREADY_INITIALIZED
            #endif
            ) {
                return -1;
            }
            initialized = 1;
        }

        while (remaining > 0) {
            int length;
            available = 0;
            nrf_drv_rng_bytes_available(&available); /* void func */
            length = (remaining < available) ? remaining : available;
            if (length > 0) {
                err_code = nrf_drv_rng_rand(&output[pos], length);
                if (err_code != NRF_SUCCESS) {
                    break;
                }
                remaining -= length;
                pos += length;
            }
        }

        return (err_code == NRF_SUCCESS) ? 0 : -1;
    }

#elif defined(HAVE_WNR)

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        if (os == NULL || output == NULL || wnr_ctx == NULL ||
                wnr_timeout < 0) {
            return BAD_FUNC_ARG;
        }

    #ifndef WOLFSSL_MUTEX_INITIALIZER
        if (WOLFSSL_ATOMIC_LOAD(wnr_mutex_inited) != 2) {
            WOLFSSL_MSG("netRandom context must be created before use");
            return RNG_FAILURE_E;
        }
    #endif

        if (wc_LockMutex(&wnr_mutex) != 0) {
            WOLFSSL_MSG("Bad Lock Mutex wnr_mutex");
            return BAD_MUTEX_E;
        }

        if (wnr_get_entropy(wnr_ctx, wnr_timeout, output, sz, sz) !=
                WNR_ERROR_NONE)
            return RNG_FAILURE_E;

        wc_UnLockMutex(&wnr_mutex);

        return 0;
    }

#elif defined(INTIME_RTOS)
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        uint32_t randval;
        word32 len;

        if (output == NULL) {
            return BUFFER_E;
        }

    #ifdef INTIMEVER
        /* If INTIMEVER exists then it is INTIME RTOS v6 or later */
        #define INTIME_RAND_FUNC arc4random
        len = 4;
    #else
        /* v5 and older */
        #define INTIME_RAND_FUNC rand
        srand(time(0));
        len = 2; /* don't use all 31 returned bits */
    #endif

        while (sz > 0) {
            if (sz < len)
                len = sz;
            randval = INTIME_RAND_FUNC();
            XMEMCPY(output, &randval, len);
            output += len;
            sz -= len;
        }
        (void)os;

        return 0;
    }

#elif defined(WOLFSSL_WICED)
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        int ret;
        (void)os;

        if (output == NULL || UINT16_MAX < sz) {
            return BUFFER_E;
        }

        if ((ret = wiced_crypto_get_random((void*) output, sz) )
                         != WICED_SUCCESS) {
            return ret;
        }

        return ret;
    }

#elif defined(WOLFSSL_NETBURNER)
    #warning using NetBurner pseudo random GetRandomByte for seed
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        word32 i;
        (void)os;

        if (output == NULL) {
            return BUFFER_E;
        }

        for (i = 0; i < sz; i++) {
            output[i] = GetRandomByte();

            /* check if was a valid random number */
            if (!RandomValid())
                return RNG_FAILURE_E;
        }

        return 0;
    }
#elif defined(IDIRECT_DEV_RANDOM)

    extern int getRandom( int sz, unsigned char *output );

    int GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        int num_bytes_returned = 0;

        num_bytes_returned = getRandom( (int) sz, (unsigned char *) output );

        return 0;
    }

#elif defined(WOLFSSL_CAAM)

    #include <wolfssl/wolfcrypt/port/caam/wolfcaam.h>

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        unsigned int args[4] = {0};
        CAAM_BUFFER buf[1];
        int ret    = 0;
        int times  = 1000, i; /* 1000 is an arbitrary number chosen */
        word32 idx = 0;

        (void)os;

        if (output == NULL) {
            return BUFFER_E;
        }

        /* Check Waiting to make sure entropy is ready */
        for (i = 0; i < times; i++) {
            buf[0].BufferType = DataBuffer | LastBuffer;
            buf[0].TheAddress = (CAAM_ADDRESS)(output + idx);
            buf[0].Length     = ((sz - idx) < WC_CAAM_MAX_ENTROPY)?
                                sz - idx : WC_CAAM_MAX_ENTROPY;

            args[0] = buf[0].Length;
            ret = wc_caamAddAndWait(buf, 1, args, CAAM_ENTROPY);
            if (ret == 0) {
                idx += buf[0].Length;
                if (idx == sz)
                    break;
            }

            /* driver could be waiting for entropy */
            if (ret != WC_NO_ERR_TRACE(RAN_BLOCK_E) && ret != 0) {
                return ret;
            }
#ifndef WOLFSSL_IMXRT1170_CAAM
            usleep(100);
#endif
        }

        if (i == times && ret != 0) {
             return RNG_FAILURE_E;
        }
        else { /* Success case */
            ret = 0;
        }

        return ret;
    }

#elif defined(WOLFSSL_APACHE_MYNEWT)

    #include <stdlib.h>
    #include "os/os_time.h"
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        int i;
        srand(os_time_get());

        for (i = 0; i < sz; i++ ) {
            output[i] = rand() % 256;
            if ((i % 8) == 7) {
                srand(os_time_get());
            }
        }

        return 0;
    }

#elif defined(ARDUINO)

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        int ret = 0;
        word32 rand;
        while (sz > 0) {
            word32 len = sizeof(rand);
            if (sz < len)
                len = sz;
        /* Get an Arduino framework random number */
        #if defined(ARDUINO_SAMD_NANO_33_IOT) || \
            defined(ARDUINO_ARCH_RP2040)
            /* Known, tested boards working with random() */
            rand = random();
        #elif defined(ARDUINO_SAM_DUE)
            /* See: https://github.com/avrxml/asf/tree/master/sam/utils/cmsis/sam3x/include */
            #if defined(__SAM3A4C__)
                #ifndef TRNG
                    #define TRNG (0x400BC000U)
                #endif
            #elif defined(__SAM3A8C__)
                #ifndef TRNG
                    #define TRNG (0x400BC000U)
                #endif
            #elif defined(__SAM3X4C__)
                #ifndef TRNG
                    #define TRNG (0x400BC000U)
                #endif
            #elif defined(__SAM3X4E__)
                #ifndef TRNG
                    #define TRNG (0x400BC000U)
                #endif
            #elif defined(__SAM3X8C__)
                #ifndef TRNG
                    #define TRNG (0x400BC000U)
                #endif
            #elif defined(__SAM3X8E__)
                /* This is the Arduino Due */
                #ifndef TRNG
                    #define TRNG (0x400BC000U)
                #endif
            #elif  defined(__SAM3A8H__)
                #ifndef TRNG
                    #define TRNG (0x400BC000U)
                #endif
            #else
                #ifndef TRNG
                    #error "Unknown TRNG for this device"
                #endif
            #endif

            srand(analogRead(0));
            rand = trng_read_output_data(TRNG);
        #elif defined(__STM32__)
            /* TODO: confirm this is proper random number on Arduino STM32 */
            #warning "Not yet tested on STM32 targets"
            rand = random();
        #else
            /* TODO: Pull requests appreciated for new targets.
             * Do *all* other Arduino boards support random()?
             * Probably not 100%, but most will likely work: */
            rand = random();
        #endif

            XMEMCPY(output, &rand, len);
            output += len;
            sz -= len;
        }

        return ret;
    }

#elif defined(WOLFSSL_ESPIDF)

    /* Espressif */
    #if defined(WOLFSSL_ESP32) || defined(WOLFSSL_ESPWROOM32SE)

        /* Espressif ESP32 */
        #include <esp_system.h>
        #if defined(CONFIG_IDF_TARGET_ESP32S2) || \
            defined(CONFIG_IDF_TARGET_ESP32S3)
            #include <esp_random.h>
        #endif

        int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
        {
            word32 rand;
            while (sz > 0) {
                word32 len = sizeof(rand);
                if (sz < len)
                    len = sz;
                /* Get one random 32-bit word from hw RNG */
                rand = esp_random( );
                XMEMCPY(output, &rand, len);
                output += len;
                sz -= len;
            }

            return 0;
        }

    #elif defined(WOLFSSL_ESP8266)

        /* Espressif ESP8266 */
        #include <esp_system.h>

        int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
        {
    #if defined(DEBUG_WOLFSSL)
            WOLFSSL_ENTER("ESP8266 Random");
    #endif
            word32 rand;
            while (sz > 0) {
                word32 len = sizeof(rand);
                if (sz < len)
                    len = sz;
                /* Get one random 32-bit word from hw RNG */
                rand = esp_random( );
                XMEMCPY(output, &rand, len);
                output += len;
                sz -= len;
            }

            return 0;
        }
    #endif /* end WOLFSSL_ESPIDF */

#elif defined(WOLFSSL_LINUXKM)

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        (void)os;
        int ret = WC_NO_ERR_TRACE(RNG_FAILURE_E);

    #ifdef HAVE_ENTROPY_MEMUSE
        ret = wc_Entropy_Get(MAX_ENTROPY_BITS, output, sz);
        if (ret == 0)
            return 0;
        #ifdef ENTROPY_MEMUSE_FORCE_FAILURE
        return ret;
        #endif
    #endif

    #if defined(HAVE_INTEL_RDSEED) || defined(HAVE_AMD_RDSEED)
        if (IS_INTEL_RDSEED(intel_flags)) {
            ret = wc_GenerateSeed_IntelRD(NULL, output, sz);
            if (ret == 0)
                return 0;
            #ifdef FORCE_FAILURE_RDSEED
            return ret;
            #endif
        }
    #ifdef FORCE_FAILURE_RDSEED
        else {
            /* Don't fall back to get_random_bytes() */
            return MISSING_RNG_E;
        }
    #endif
    #endif /* HAVE_INTEL_RDSEED || HAVE_AMD_RDSEED */

    #ifdef LINUXKM_LKCAPI_REGISTER_HASH_DRBG_DEFAULT
        #if !defined(HAVE_ENTROPY_MEMUSE) && \
            !defined(HAVE_INTEL_RDSEED) && \
            !defined(HAVE_AMD_RDSEED)
            #error LINUXKM_LKCAPI_REGISTER_HASH_DRBG_DEFAULT requires an intrinsic entropy source.
        #else
            return ret;
        #endif
    #else
        (void)ret;

        get_random_bytes(output, sz);
        return 0;
    #endif
    }

#elif defined(WOLFSSL_BSDKM)
    #include <sys/random.h>
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        (void)os;
        int ret = WC_NO_ERR_TRACE(RNG_FAILURE_E);

    #ifdef HAVE_ENTROPY_MEMUSE
        ret = wc_Entropy_Get(MAX_ENTROPY_BITS, output, sz);
        if (ret == 0) {
            return 0;
        }
        #ifdef ENTROPY_MEMUSE_FORCE_FAILURE
        /* Don't fallback to /dev/urandom. */
        return ret;
        #endif
    #endif

    #if defined(HAVE_INTEL_RDSEED) || defined(HAVE_AMD_RDSEED)
        if (IS_INTEL_RDSEED(intel_flags)) {
            ret = wc_GenerateSeed_IntelRD(NULL, output, sz);
        #ifndef FORCE_FAILURE_RDSEED
            if (ret == 0)
        #endif
            {
                return ret;
            }
        }
    #ifdef FORCE_FAILURE_RDSEED
        else {
            /* Don't fall back to arc4random_buf() */
            return MISSING_RNG_E;
        }
    #endif
    #endif /* HAVE_INTEL_RDSEED || HAVE_AMD_RDSEED */

        (void)ret;

        arc4random_buf(output, sz);
        return 0;
    }
#elif defined(WOLFSSL_RENESAS_TSIP)

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        (void)os;
        return wc_tsip_GenerateRandBlock(output, sz);
    }


#elif defined(WOLFSSL_SCE) && !defined(WOLFSSL_SCE_NO_TRNG)
    #include "hal_data.h"

    #ifndef WOLFSSL_SCE_TRNG_HANDLE
        #define WOLFSSL_SCE_TRNG_HANDLE g_sce_trng
    #endif

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        word32 ret;
        word32 blocks;
        word32 len = sz;

        ret = WOLFSSL_SCE_TRNG_HANDLE.p_api->open(WOLFSSL_SCE_TRNG_HANDLE.p_ctrl,
                                                  WOLFSSL_SCE_TRNG_HANDLE.p_cfg);
        if (ret != SSP_SUCCESS && ret != SSP_ERR_CRYPTO_ALREADY_OPEN) {
            /* error opening TRNG driver */
            return -1;
        }

        blocks = sz / sizeof(word32);
        if (blocks > 0) {
            ret = WOLFSSL_SCE_TRNG_HANDLE.p_api->read(WOLFSSL_SCE_TRNG_HANDLE.p_ctrl,
                                                       (word32*)output, blocks);
            if (ret != SSP_SUCCESS) {
                return -1;
            }
        }

        len = len - (blocks * sizeof(word32));
        if (len > 0) {
            word32 tmp;

            if (len > sizeof(word32)) {
                return -1;
            }
            ret = WOLFSSL_SCE_TRNG_HANDLE.p_api->read(WOLFSSL_SCE_TRNG_HANDLE.p_ctrl,
                                                      (word32*)&tmp, 1);
            if (ret != SSP_SUCCESS) {
                return -1;
            }
            XMEMCPY(output + (blocks * sizeof(word32)), (byte*)&tmp, len);
        }

        ret = WOLFSSL_SCE_TRNG_HANDLE.p_api->close(WOLFSSL_SCE_TRNG_HANDLE.p_ctrl);
        if (ret != SSP_SUCCESS) {
            /* error opening TRNG driver */
            return -1;
        }
        return 0;
    }
#elif defined(CUSTOM_RAND_GENERATE_BLOCK)
    /* #define CUSTOM_RAND_GENERATE_BLOCK myRngFunc
     * extern int myRngFunc(byte* output, word32 sz);
     */

#elif defined(__MICROBLAZE__)
    #warning weak source of entropy
    #define LPD_SCNTR_BASE_ADDRESS 0xFF250000

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        word32* cnt;
        word32 i;

        /* using current time with srand */
        cnt = (word32*)LPD_SCNTR_BASE_ADDRESS;
        srand(*cnt | *(cnt+1));

        for (i = 0; i < sz; i++)
            output[i] = rand();

        (void)os;
        return 0;
    }

#elif defined(WOLFSSL_ZEPHYR)

    #ifdef __has_include
        #if __has_include(<zephyr/version.h>)
            #include <zephyr/version.h>
        #else
            #include <version.h>
        #endif
    #else
        #include <version.h>
    #endif

    #include <sys/types.h>

    #if KERNEL_VERSION_NUMBER >= 0x30500
        #include <zephyr/random/random.h>
    #else
        #if KERNEL_VERSION_NUMBER >= 0x30100
            #include <zephyr/random/rand32.h>
        #else
            #include <random/rand32.h>
        #endif
    #endif

    #if KERNEL_VERSION_NUMBER >= 0x40300
        #include <time.h>
    #elif KERNEL_VERSION_NUMBER >= 0x30100
        #include <zephyr/posix/time.h>
    #else
        #include <posix/time.h>
    #endif

    #if KERNEL_VERSION_NUMBER >= 0x30100
        #include <zephyr/devicetree.h>
    #else
        #include <devicetree.h>
    #endif

    #if defined(CONFIG_ENTROPY_HAS_DRIVER) && DT_HAS_CHOSEN(zephyr_entropy)
        #if KERNEL_VERSION_NUMBER >= 0x30100
            #include <zephyr/device.h>
            #include <zephyr/drivers/entropy.h>
        #else
            #include <device.h>
            #include <drivers/entropy.h>
        #endif
    #endif

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
    /* Seed the DRBG straight from the hardware entropy driver when the platform
     * exposes one (a zephyr,entropy chosen node), so wolfCrypt gets
     * cryptographic-quality seed material instead of the general-purpose
     * sys_rand_get(). A dead source returns an error, which makes wc_InitRng()
     * fail (RNG_FAILURE_E) rather than yield weak output. Boards that set
     * CONFIG_ENTROPY_HAS_DRIVER without a chosen entropy node fall back to
     * sys_rand_get() rather than failing the build. */
    #if defined(CONFIG_ENTROPY_HAS_DRIVER) && DT_HAS_CHOSEN(zephyr_entropy)
        const struct device *dev = DEVICE_DT_GET(DT_CHOSEN(zephyr_entropy));
        word32 off = 0;
        word32 rem;
        uint16_t chunk;

        (void)os;
        if (!device_is_ready(dev)) {
            return RNG_FAILURE_E;
        }
        /* entropy_get_entropy() takes a uint16_t length; chunk the request so
         * any word32 seed size is honored without silent truncation. */
        while (off < sz) {
            rem = sz - off;
            chunk = (rem > 0xFFFFU) ? (uint16_t)0xFFFFU : (uint16_t)rem;
            if (entropy_get_entropy(dev, (uint8_t *)output + off, chunk) != 0) {
                return RNG_FAILURE_E;
            }
            off += chunk;
        }
        return 0;
    #else
        (void)os;
        sys_rand_get(output, sz);
        return 0;
    #endif
    }

#elif defined(WOLFSSL_TELIT_M2MB)

        #include "stdlib.h"
        static long get_timestamp(void) {
            long myTime = 0;
            INT32 fd = m2mb_rtc_open("/dev/rtc0", 0);
            if (fd >= 0) {
                M2MB_RTC_TIMEVAL_T timeval;
                m2mb_rtc_ioctl(fd, M2MB_RTC_IOCTL_GET_TIMEVAL, &timeval);
                myTime = timeval.msec;
                m2mb_rtc_close(fd);
            }
            return myTime;
        }
        int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
        {
            int i;
            srand(get_timestamp());
            for (i = 0; i < sz; i++ ) {
                output[i] = rand() % 256;
                if ((i % 8) == 7) {
                    srand(get_timestamp());
                }
            }
            return 0;
        }
#elif defined(WOLFSSL_SE050) && !defined(WOLFSSL_SE050_NO_TRNG)
     #include <wolfssl/wolfcrypt/port/nxp/se050_port.h>

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz){
        (void)os;

        if (output == NULL) {
            return BUFFER_E;
        }
        return se050_get_random_number(sz, output);
    }

#elif defined(WOLFSSL_NXP_RNG_1)
    #include "fsl_rng.h"

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz) {
        (void)os;

        if (output == NULL) {
            return BUFFER_E;
        }

        if (RNG_GetRandomData(RNG, output, sz) != kStatus_Success)
            return RNG_FAILURE_E;

        return 0;
    }

#elif defined(WOLFSSL_VA416X0_TRNG)
    /* Vorago VA416x0 hardware TRNG (an Arm CryptoCell-style entropy block).
     * Used to seed the SP800-90A Hash-DRBG (keep HAVE_HASHDRBG enabled); the
     * TRNG yields only ~1.25 kb/s of entropy, so the DRBG expands it.
     *
     * Build: define WOLFSSL_VA416X0_TRNG, and have the VA416xx SDK header
     * "va416xx.h" on the include path (provides VOR_SYSCONFIG / VOR_TRNG and
     * the register field macros). There is no SDK HAL driver for the TRNG, so
     * it is accessed at the register level below. The tuning macros
     * WOLFSSL_VA416X0_TRNG_SAMPLE_CNT, WOLFSSL_VA416X0_TRNG_MAX_RETRY and
     * WOLFSSL_VA416X0_TRNG_TIMEOUT have overridable defaults defined below.
     *
     * Note: the TRNG PERIPHERAL_RESET bit is active low and must be released
     * or every TRNG register write is silently ignored. */
    #include "va416xx.h"

    /* Ring-oscillator sample count (must be non-zero). May need tuning on
     * hardware: too low results in repeated autocorrelation/CRNGT errors. */
    #ifndef WOLFSSL_VA416X0_TRNG_SAMPLE_CNT
        #define WOLFSSL_VA416X0_TRNG_SAMPLE_CNT 1000
    #endif
    #ifndef WOLFSSL_VA416X0_TRNG_MAX_RETRY
        #define WOLFSSL_VA416X0_TRNG_MAX_RETRY 10
    #endif
    /* Max poll iterations waiting for one 192-bit entropy block before
     * giving up (guards against a non-responsive TRNG). */
    #ifndef WOLFSSL_VA416X0_TRNG_TIMEOUT
        #define WOLFSSL_VA416X0_TRNG_TIMEOUT 1000000
    #endif
    #if WOLFSSL_VA416X0_TRNG_SAMPLE_CNT == 0
        #error "WOLFSSL_VA416X0_TRNG_SAMPLE_CNT must be non-zero"
    #endif
    #if WOLFSSL_VA416X0_TRNG_TIMEOUT == 0
        #error "WOLFSSL_VA416X0_TRNG_TIMEOUT must be non-zero"
    #endif

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        word32 i;
        word32 reg;
        word32 chunk;
        word32 timeout;
        word32 entropy[6]; /* 192-bit entropy holding register */
        int retry;
        int ret;

        (void)os;

        if (output == NULL) {
            return BUFFER_E;
        }

        /* serialize access to the shared TRNG hardware */
        ret = wolfSSL_CryptHwMutexLock();
        if (ret != 0) {
            return ret;
        }

        /* enable the TRNG peripheral clock and release it from reset (the
         * reset bit is active low: 0 = held in reset, 1 = released) */
        VOR_SYSCONFIG->PERIPHERAL_CLK_ENABLE |=
            SYSCONFIG_PERIPHERAL_CLK_ENABLE_TRNG_Msk;
        VOR_SYSCONFIG->PERIPHERAL_RESET |=
            SYSCONFIG_PERIPHERAL_RESET_TRNG_Msk;

        /* mask all interrupts (poll instead) and clear any stale status */
        VOR_TRNG->IMR = TRNG_IMR_EHR_VALID_INT_MASK_Msk |
                        TRNG_IMR_AUTOCORR_ERR_INT_MASK_Msk |
                        TRNG_IMR_CRNGT_ERR_INT_MASK_Msk |
                        TRNG_IMR_VN_ERR_INT_MASK_Msk;
        VOR_TRNG->ICR = TRNG_ICR_EHR_VALID_Msk | TRNG_ICR_AUTOCORR_ERR_Msk |
                        TRNG_ICR_CRNGT_ERR_Msk | TRNG_ICR_VN_ERR_Msk;

        /* CONFIG = 0 sets RND_SRC_SEL = 0, which selects the ring-oscillator
         * entropy source (per the VA416x0 reference manual) and clears the
         * rest of the register; set the sample rate and keep the health tests
         * enabled (no DEBUG_CONTROL bypass) */
        VOR_TRNG->CONFIG = 0;
        VOR_TRNG->SAMPLE_CNT1 = WOLFSSL_VA416X0_TRNG_SAMPLE_CNT;
        VOR_TRNG->DEBUG_CONTROL = 0;

        for (i = 0; i < sz; ) {
            retry = 0;
            timeout = WOLFSSL_VA416X0_TRNG_TIMEOUT;

            /* start entropy collection */
            VOR_TRNG->RND_SOURCE_ENABLE =
                TRNG_RND_SOURCE_ENABLE_RND_SRC_EN_Msk;

            for (;;) {
                reg = VOR_TRNG->ISR;
                if ((reg & (TRNG_ISR_AUTOCORR_ERR_Msk |
                            TRNG_ISR_CRNGT_ERR_Msk |
                            TRNG_ISR_VN_ERR_Msk)) != 0) {
                    /* health-test failure: stop, then clear the error flags
                     * and any latched EHR_VALID so a stale/invalid block is
                     * not consumed on the next iteration, then re-collect */
                    VOR_TRNG->RND_SOURCE_ENABLE = 0;
                    VOR_TRNG->ICR = TRNG_ICR_EHR_VALID_Msk |
                                    TRNG_ICR_AUTOCORR_ERR_Msk |
                                    TRNG_ICR_CRNGT_ERR_Msk |
                                    TRNG_ICR_VN_ERR_Msk;
                    if (++retry > WOLFSSL_VA416X0_TRNG_MAX_RETRY) {
                        ForceZero(entropy, sizeof(entropy));
                        wolfSSL_CryptHwMutexUnLock();
                        return RNG_FAILURE_E;
                    }
                    timeout = WOLFSSL_VA416X0_TRNG_TIMEOUT;
                    VOR_TRNG->RND_SOURCE_ENABLE =
                        TRNG_RND_SOURCE_ENABLE_RND_SRC_EN_Msk;
                    continue;
                }
                if ((VOR_TRNG->VALID & TRNG_VALID_EHR_VALID_Msk) != 0) {
                    break;
                }
                if (--timeout == 0) {
                    VOR_TRNG->RND_SOURCE_ENABLE = 0;
                    ForceZero(entropy, sizeof(entropy));
                    wolfSSL_CryptHwMutexUnLock();
                    return RNG_FAILURE_E;
                }
            }

            /* read 192 bits of entropy (6 x 32-bit words) */
            entropy[0] = VOR_TRNG->EHR_DATA0;
            entropy[1] = VOR_TRNG->EHR_DATA1;
            entropy[2] = VOR_TRNG->EHR_DATA2;
            entropy[3] = VOR_TRNG->EHR_DATA3;
            entropy[4] = VOR_TRNG->EHR_DATA4;
            entropy[5] = VOR_TRNG->EHR_DATA5;

            /* reading EHR_DATA clears EHR_VALID; stop the source and ack */
            VOR_TRNG->RND_SOURCE_ENABLE = 0;
            VOR_TRNG->ICR = TRNG_ICR_EHR_VALID_Msk;

            chunk = sz - i;
            if (chunk > sizeof(entropy)) {
                chunk = sizeof(entropy);
            }
            XMEMCPY(&output[i], (byte*)entropy, chunk);
            i += chunk;
        }

        ForceZero(entropy, sizeof(entropy)); /* scrub seed material from stack */
        wolfSSL_CryptHwMutexUnLock();
        return 0;
    }

#elif defined(WOLFSSL_C2000_ENTROPY)
    /* TI C2000 (C28x) oscillator-jitter entropy source.  The part has no
     * TRNG; the noise bit is the LSB of a Dual-Clock Comparator measurement,
     * oversampled past its measured min-entropy, health-tested per SP800-90B
     * 4.4 and SHA-256 conditioned before feeding the Hash-DRBG.
     *
     * Build: define WOLFSSL_C2000_ENTROPY and add
     * wolfcrypt/src/port/ti/ti-c2000-entropy.c with the C2000Ware driverlib
     * headers on the include path.  Tuning macros, hardware overrides and the
     * characterization: wolfssl/wolfcrypt/port/ti/ti-c2000-entropy.h and
     * IDE/C2000/README.md.
     *
     * Blocking by design: ~26 ms per 32-octet chunk per source at the default
     * window, ~100 ms for a typical seed, ~420 ms for the one-time startup
     * test.  Fine at boot, not for a control loop. */
    #if !defined(HAVE_HASHDRBG)
        #error "WOLFSSL_C2000_ENTROPY expects HAVE_HASHDRBG to expand the seed"
    #endif

    #include <wolfssl/wolfcrypt/port/ti/ti-c2000-entropy.h>

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        (void)os;

        if (output == NULL) {
            return BUFFER_E;
        }

        return wc_c2000_GenerateSeed(output, sz);
    }

#elif defined(DOLPHIN_EMULATOR) || defined (WOLFSSL_NDS)

        int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
        {
            word32 i;
            (void)os;
            srand(time(NULL));
            for (i = 0; i < sz; i++)
                output[i] = (byte)rand();
            return 0;
        }
#elif defined(WOLFSSL_MAXQ108X) || defined(WOLFSSL_MAXQ1065)

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        (void)os;

        return maxq10xx_random(output, sz);
    }
#elif defined(MAX3266X_RNG)
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        int status;
        static int initDone = 0;
        (void)os;
        if (initDone == 0) {
            status = wolfSSL_HwRngMutexLock();
            if (status != 0) {
                return status;
            }
            if(MXC_TRNG_HealthTest() != 0) {
                #ifdef DEBUG_WOLFSSL
                WOLFSSL_MSG("TRNG HW Health Test Failed");
                #endif /* DEBUG_WOLFSSL */
                wolfSSL_HwRngMutexUnLock();
                return WC_HW_E;
            }
            wolfSSL_HwRngMutexUnLock();
            initDone = 1;
        }
        return wc_MXC_TRNG_Random(output, sz);
    }

#elif defined(CY_USING_HAL) && defined(COMPONENT_WOLFSSL)

    /* Infineon/Cypress HAL RNG implementation */
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        cyhal_trng_t obj;
        cy_rslt_t result;
        uint32_t val;
        word32 i = 0;

        (void)os;

        result = cyhal_trng_init(&obj);
        if (result == CY_RSLT_SUCCESS) {
            while (i < sz) {
                /* If not aligned or there is odd/remainder add single byte */
                if( (i + sizeof(word32)) > sz ||
                    ((wc_ptr_t)&output[i] % sizeof(word32)) != 0
                ) {
                    val = cyhal_trng_generate(&obj);
                    output[i++] = (byte)val;
                }
                else {
                    /* Use native 32 instruction */
                    val = cyhal_trng_generate(&obj);
                    *((uint32_t*)&output[i]) = val;
                    i += sizeof(word32);
                }
            }
            cyhal_trng_free(&obj);
        }
        return 0;
    }

#elif defined(WOLFSSL_SAFERTOS) || defined(WOLFSSL_LEANPSK) || \
      defined(WOLFSSL_IAR_ARM)  || defined(WOLFSSL_MDK_ARM) || \
      defined(WOLFSSL_uITRON4)  || defined(WOLFSSL_uTKERNEL2) || \
      defined(WOLFSSL_LPC43xx)  || defined(NO_STM32_RNG) || \
      defined(MBED)             || defined(WOLFSSL_EMBOS) || \
      defined(WOLFSSL_GENSEED_FORTEST) || defined(WOLFSSL_CHIBIOS) || \
      defined(WOLFSSL_CONTIKI)  || defined(WOLFSSL_AZSPHERE)

    /* these platforms do not have a default random seed and
       you'll need to implement your own wc_GenerateSeed or define via
       CUSTOM_RAND_GENERATE_BLOCK */

    #define USE_TEST_GENSEED

#elif defined(NO_DEV_RANDOM)

    /* Allow bare-metal targets to use cryptoCb as seed provider */
    #if defined(WOLF_CRYPTO_CB)

    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        int ret = WC_NO_ERR_TRACE(WC_HW_E);

        #ifndef WOLF_CRYPTO_CB_FIND
        if (os->devId != INVALID_DEVID)
        #endif
        {
            ret = wc_CryptoCb_RandomSeed(os, output, sz);
            if (ret == WC_NO_ERR_TRACE(CRYPTOCB_UNAVAILABLE)) {
                ret = WC_HW_E;
            }
        }

        return ret;
    }

    #else /* defined(WOLF_CRYPTO_CB)*/

    #error "you need to write an os specific wc_GenerateSeed() here"

    /*
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        return 0;
    }
    */

   #endif  /* !defined(WOLF_CRYPTO_CB) */

#else

    /* may block */
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        int ret = 0;
    /* Same condition as the seed-device block below: with
     * ENTROPY_MEMUSE_FORCE_FAILURE the code that uses these is compiled out,
     * and declaring them anyway is an unused-variable error under -Werror. */
    #if defined(WC_RNG_SEED_DEVICE) && (!defined(HAVE_ENTROPY_MEMUSE) || \
        !defined(ENTROPY_MEMUSE_FORCE_FAILURE))
        byte*  devOut;
        word32 devSz;
        int    devFd;
        int    devLen;
    #endif

        /* Validate output before any entropy backend dereferences it: some
         * (e.g. glibc's vDSO getrandom()) fault on a NULL buffer rather than
         * returning an error. Mirrors wc_RNG_GenerateBlock's NULL check. */
        if (os == NULL || output == NULL) {
            return BAD_FUNC_ARG;
        }

    #ifdef WOLF_CRYPTO_CB
        #ifndef WOLF_CRYPTO_CB_FIND
        if (os->devId != INVALID_DEVID)
        #endif
        {
            ret = wc_CryptoCb_RandomSeed(os, output, sz);
            if (ret != WC_NO_ERR_TRACE(CRYPTOCB_UNAVAILABLE))
                return ret;
            /* fall-through when unavailable */
            ret = 0; /* reset error code */
        }
    #endif

    #ifdef HAVE_ENTROPY_MEMUSE
        ret = wc_Entropy_Get(MAX_ENTROPY_BITS, output, sz);
        if (ret == 0) {
            /* success, we're done */
            return ret;
        }
    #ifdef ENTROPY_MEMUSE_FORCE_FAILURE
        /* Don't fall back to /dev/urandom. */
        return ret;
    #else
        /* Reset error and fall back to using /dev/urandom. */
        ret = 0;
    #endif
    #endif

    #if !defined(HAVE_ENTROPY_MEMUSE) || !defined(ENTROPY_MEMUSE_FORCE_FAILURE)

    #ifdef WC_RNG_SEED_DEVICE
        /* Nominated entropy source, usually a hardware RNG. Best effort: on
         * any failure fall through to the default sources below. Those refill
         * the whole request from the start, so bytes a partial read left in
         * output are overwritten rather than mixed in. */
        devOut = output;
        devSz  = sz;
        devFd  = wc_open_cloexec(WC_RNG_SEED_DEVICE, O_RDONLY);
        if (devFd != XBADFD) {
            while (devSz > 0) {
                errno = 0;
                devLen = (int)read(devFd, devOut, devSz);
                if (devLen < 0) {
                    if (errno == EINTR)
                        continue; /* interrupted, read again */
                    break;
                }
                if (devLen == 0)
                    break;        /* at EOF, will never fill the request */

                devSz  -= (word32)devLen;
                devOut += devLen;
            }
            close(devFd);
        }
        #if defined(DEBUG_WOLFSSL)
            if (devSz == 0)
                WOLFSSL_MSG("seeded from WC_RNG_SEED_DEVICE.");
            else
                WOLFSSL_MSG("WC_RNG_SEED_DEVICE unusable, using default.");
        #endif /* DEBUG_WOLFSSL */
        if (devSz == 0) {
            /* success, we're done */
            return 0;
        }
    #endif /* WC_RNG_SEED_DEVICE */

    #if defined(HAVE_INTEL_RDSEED) || defined(HAVE_AMD_RDSEED)
        if (IS_INTEL_RDSEED(intel_flags)) {
             ret = wc_GenerateSeed_IntelRD(NULL, output, sz);
             if (ret == 0) {
                 /* success, we're done */
                 return ret;
             }
        #ifdef FORCE_FAILURE_RDSEED
             /* Don't fall back to /dev/urandom. */
             return ret;
        #else
             /* Reset error and fall back to using /dev/urandom. */
             ret = 0;
        #endif
        }
    #ifdef FORCE_FAILURE_RDSEED
        else {
            /* Don't fall back to /dev/urandom */
            return MISSING_RNG_E;
        }
    #endif
    #endif /* HAVE_INTEL_RDSEED || HAVE_AMD_RDSEED */

    #if (!defined(HAVE_INTEL_RDSEED) && !defined(HAVE_AMD_RDSEED)) || \
        !defined(FORCE_FAILURE_RDSEED)

    #if defined(WOLFSSL_GETRANDOM) || defined(HAVE_GETRANDOM)
        {
            word32 grSz = sz;
            byte* grOutput = output;

            while (grSz) {
                ssize_t len;

                errno = 0;
                len = getrandom(grOutput, grSz, 0);
                if (len == -1) {
                    if (errno == EINTR) {
                        /* interrupted, call getrandom again */
                        continue;
                    }
                    else {
                        ret = READ_RAN_E;
                    }
                    break;
                }

                grSz     -= (word32)len;
                grOutput += len;
            }
            if (ret == 0)
                return ret;
        #ifdef FORCE_FAILURE_GETRANDOM
            /* don't fall back to /dev/urandom */
            return ret;
        #elif !defined(NO_FILESYSTEM)
            /* reset error and fall back to using /dev/urandom if filesystem
             * support is compiled in */
            ret = 0;
        #endif
        }
    #endif

#ifndef NO_FILESYSTEM
    #ifdef WOLFSSL_KEEP_RNG_SEED_FD_OPEN
        if (!os->seedFdOpen)
        {
            os->fd = XBADFD;
        #ifndef NO_DEV_URANDOM /* way to disable use of /dev/urandom */
            if (os->fd == XBADFD) {
                os->fd = wc_open_cloexec("/dev/urandom", O_RDONLY);
            #if defined(DEBUG_WOLFSSL)
                if (os->fd != XBADFD)
                    WOLFSSL_MSG("opened /dev/urandom.");
            #endif /* DEBUG_WOLFSSL */
            }
        #endif /* NO_DEV_URANDOM */
            if (os->fd == XBADFD) {
                /* may still have /dev/random */
                os->fd = wc_open_cloexec("/dev/random", O_RDONLY);
            #if defined(DEBUG_WOLFSSL)
                if (os->fd != XBADFD)
                    WOLFSSL_MSG("opened /dev/random.");
            #endif /* DEBUG_WOLFSSL */
                if (os->fd == XBADFD)
                    return OPEN_RAN_E;
                os->keepSeedFdOpen = 0;
                os->seedFdOpen = 1;
            }
            else {
                os->keepSeedFdOpen = 1;
                os->seedFdOpen = 1;
            }
        }
    #else /* WOLFSSL_KEEP_RNG_SEED_FD_OPEN */
        os->fd = XBADFD;
    #ifndef NO_DEV_URANDOM /* way to disable use of /dev/urandom */
        if (os->fd == XBADFD) {
            os->fd = wc_open_cloexec("/dev/urandom", O_RDONLY);
        #if defined(DEBUG_WOLFSSL)
            if (os->fd != XBADFD)
                WOLFSSL_MSG("opened /dev/urandom.");
        #endif /* DEBUG_WOLFSSL */
        }
    #endif /* !NO_DEV_URANDOM */
        if (os->fd == XBADFD) {
            /* may still have /dev/random */
            os->fd = wc_open_cloexec("/dev/random", O_RDONLY);
        #if defined(DEBUG_WOLFSSL)
            if (os->fd != XBADFD)
                WOLFSSL_MSG("opened /dev/random.");
        #endif /* DEBUG_WOLFSSL */
            if (os->fd == XBADFD)
                return OPEN_RAN_E;
        }
    #endif /* WOLFSSL_KEEP_RNG_SEED_FD_OPEN */
    #if defined(DEBUG_WOLFSSL)
        WOLFSSL_MSG("rnd read...");
    #endif /* DEBUG_WOLFSSL */
        while (sz) {
            int len = (int)read(os->fd, output, sz);
            /* EOF never fills the request, don't retry forever */
            if (len <= 0) {
                ret = READ_RAN_E;
                break;
            }

            sz     -= (word32)len;
            output += len;

            if (sz) {
    #if defined(BLOCKING) || defined(WC_RNG_BLOCKING)
                sleep(0);             /* context switch */
    #else
                ret = RAN_BLOCK_E;
                break;
    #endif /* BLOCKING || WC_RNG_BLOCKING */
            }
        }
    #ifdef WOLFSSL_KEEP_RNG_SEED_FD_OPEN
        if (!os->keepSeedFdOpen && os->seedFdOpen)
        {
            close(os->fd);
            os->fd = -1;
            os->seedFdOpen = 0;
        }
    #else
        close(os->fd);
    #endif /* WOLFSSL_KEEP_RNG_SEED_FD_OPEN */
#else /* NO_FILESYSTEM */
        (void)output;
        (void)sz;
        ret = NOT_COMPILED_IN;
#endif /* NO_FILESYSTEM */

        return ret;

    #endif /* (!HAVE_INTEL_RDSEED && !HAVE_AMD_RDSEED) || !FORCE_FAILURE_RDSEED */

    #endif /*!HAVE_ENTROPY_MEMUSE || !ENTROPY_MEMUSE_FORCE_FAILURE */

    }

#endif

#ifdef USE_TEST_GENSEED
    #if !defined(_MSC_VER) && !defined(__TASKING__)
        #warning "write a real random seed!!!!, just for testing now"
    #else
        #pragma message("Warning: write a real random seed!!!!, just for testing now")
    #endif
    int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
    {
        word32 i;
        /* WC_OCTET, not (byte): the cast does not truncate where
         * CHAR_BIT != 8, so sz > 256 would emit values above 0xFF. */
        for (i = 0; i < sz; i++ )
            output[i] = WC_OCTET(i);

        (void)os;

        return 0;
    }
#endif
/* End wc_GenerateSeed */

#if defined(CUSTOM_RAND_GENERATE_BLOCK) && defined(WOLFSSL_KCAPI)
#include <fcntl.h>
int wc_hwrng_generate_block(byte *output, word32 sz)
{
    int fd;
    int ret = 0;
    fd = wc_open_cloexec("/dev/hwrng", O_RDONLY);
    if (fd == -1)
        return OPEN_RAN_E;
    while(sz)
    {
        int len = (int)read(fd, output, sz);
        if (len == -1)
        {
            ret = READ_RAN_E;
            break;
        }
        sz -= len;
        output += len;
    }
    close(fd);
    return ret;
}
#endif

#ifdef WC_RNG_DEBUG_STATS

/* Note on WC_RNG_DEBUG_STATS collection points:
 *
 * Placement doctrine: each counter is maintained at the single funnel that
 * owns the distinction it records --
 *
 *   - reseed counts in Hash_DRBG_Reseed() (every reseed flavor routes
 *     through it: interval backstop, Reseed_Now, RBGC, banked redemption);
 *   - request/byte counts in the DRBG arm of wc_RNG_GenerateBlock()
 *     (hardware-offload arms -- RDRAND, Silabs, async, cryptocb, custom --
 *     are deliberately uncounted: these are DRBG-facility statistics);
 *   - banked-seed redemption provenance in wc_RNG_DRBG_NextSeedNow_Nonce();
 *   - seed health failures at the two sites that observe them per-instance
 *     (PollAndReSeed(), NextSeedGenerate);
 *   - chain-provenance bytes (RBGC_bytes_produced: output generated while
 *     the instance's own RBGCStratum > 0) in the same generate funnel;
 *   - pool byte accounting in wc_RNG_Pool_Extract(), under the consumer's
 *     instance lock: bytes produced by reading from the pool, and bytes
 *     requested but not fulfilled (empty-pool and partial-serve shortfall),
 *     so requested == produced + missed on the capacity paths.  The
 *     failed-DRBG burn path deliberately counts nothing: it is a failure
 *     event (visible via rng->status), not a capacity signal.
 *
 * Counters are plain (non-atomic) adds/increments, and update under the owner's
 * exclusive access (the lock contract shared by all WC_RNG operations) except
 * where labeled racy: those are unreliable under concurrency, by design.  Every
 * site carries its own #ifdef WC_RNG_DEBUG_STATS gate so the facility is
 * removable outright with unifdef.
 */

WOLFSSL_API int wc_rng_debug_stats_snap(struct wc_rng_debug_stats_snapshot *s,
                                        const WC_RNG *rng)
{
    if ((s == NULL) || (rng == NULL))
        return BAD_FUNC_ARG;

    s->_stats_total_bytes_requested = rng->_stats_total_bytes_requested;
    s->_stats_total_bytes_produced  = rng->_stats_total_bytes_produced;
    s->_stats_total_requests        = rng->_stats_total_requests;
    s->_stats_reseeds               = rng->_stats_reseeds;
    s->_stats_stirs                 = rng->_stats_stirs;
    s->_stats_seed_failures         = rng->_stats_seed_failures;
    s->_stats_locks_taken           = rng->_stats_locks_taken;
    s->_stats_locks_released        = rng->_stats_locks_released;
    s->_stats_locks_refused         = rng->_stats_locks_refused;
#ifdef WC_RNG_HAVE_RBGC
    s->_stats_RBGC_bytes_produced   = rng->_stats_RBGC_bytes_produced;
    s->_stats_RBGC_reseeds          = rng->_stats_RBGC_reseeds;
#endif
#ifdef WC_RNG_HAVE_POOL
    s->_stats_pool_bytes_produced   = rng->_stats_pool_bytes_produced;
    s->_stats_pool_bytes_missed     = rng->_stats_pool_bytes_missed;
#endif
#ifdef WC_RNG_HAVE_NEXT_SEED
    s->_stats_nextseedsprimary_redeemed = rng->_stats_nextseedsprimary_redeemed;
    s->_stats_nextseedsRBGC_redeemed = rng->_stats_nextseedsRBGC_redeemed;
    s->_stats_nextstirs_redeemed    = rng->_stats_nextstirs_redeemed;
    s->_stats_nextseedsbanked       = rng->_stats_nextseedsbanked;
    s->_stats_nextstirs_banked      = rng->_stats_nextstirs_banked;
#endif

    return 0;
}

WOLFSSL_API int wc_rng_debug_stats_restore(
    const struct wc_rng_debug_stats_snapshot *s,
    WC_RNG *rng)
{
    if ((s == NULL) || (rng == NULL))
        return BAD_FUNC_ARG;

    rng->_stats_total_bytes_requested = s->_stats_total_bytes_requested;
    rng->_stats_total_bytes_produced  = s->_stats_total_bytes_produced;
    rng->_stats_total_requests        = s->_stats_total_requests;
    rng->_stats_reseeds               = s->_stats_reseeds;
    rng->_stats_stirs                 = s->_stats_stirs;
    rng->_stats_seed_failures         = s->_stats_seed_failures;
    rng->_stats_locks_taken           = s->_stats_locks_taken;
    rng->_stats_locks_released        = s->_stats_locks_released;
    rng->_stats_locks_refused         = s->_stats_locks_refused;
#ifdef WC_RNG_HAVE_RBGC
    rng->_stats_RBGC_bytes_produced   = s->_stats_RBGC_bytes_produced;
    rng->_stats_RBGC_reseeds          = s->_stats_RBGC_reseeds;
#endif
#ifdef WC_RNG_HAVE_POOL
    rng->_stats_pool_bytes_produced   = s->_stats_pool_bytes_produced;
    rng->_stats_pool_bytes_missed     = s->_stats_pool_bytes_missed;
#endif
#ifdef WC_RNG_HAVE_NEXT_SEED
    rng->_stats_nextseedsprimary_redeemed = s->_stats_nextseedsprimary_redeemed;
    rng->_stats_nextseedsRBGC_redeemed = s->_stats_nextseedsRBGC_redeemed;
    rng->_stats_nextstirs_redeemed    = s->_stats_nextstirs_redeemed;
    rng->_stats_nextseedsbanked       = s->_stats_nextseedsbanked;
    rng->_stats_nextstirs_banked      = s->_stats_nextstirs_banked;
#endif

    return 0;
}

WOLFSSL_API int wc_rng_debug_stats_sum(struct wc_rng_debug_stats_snapshot *s,
                                        const WC_RNG *rng)
{
    if ((s == NULL) || (rng == NULL))
        return BAD_FUNC_ARG;

    s->_stats_total_bytes_requested += rng->_stats_total_bytes_requested;
    s->_stats_total_bytes_produced  += rng->_stats_total_bytes_produced;
    s->_stats_total_requests        += rng->_stats_total_requests;
    s->_stats_reseeds               += rng->_stats_reseeds;
    s->_stats_stirs                 += rng->_stats_stirs;
    s->_stats_seed_failures         += rng->_stats_seed_failures;
    s->_stats_locks_taken           += rng->_stats_locks_taken;
    s->_stats_locks_released        += rng->_stats_locks_released;
    s->_stats_locks_refused         += rng->_stats_locks_refused;
#ifdef WC_RNG_HAVE_RBGC
    s->_stats_RBGC_bytes_produced   += rng->_stats_RBGC_bytes_produced;
    s->_stats_RBGC_reseeds          += rng->_stats_RBGC_reseeds;
#endif
#ifdef WC_RNG_HAVE_POOL
    s->_stats_pool_bytes_produced   += rng->_stats_pool_bytes_produced;
    s->_stats_pool_bytes_missed     += rng->_stats_pool_bytes_missed;
#endif
#ifdef WC_RNG_HAVE_NEXT_SEED
    s->_stats_nextseedsprimary_redeemed += rng->_stats_nextseedsprimary_redeemed;
    s->_stats_nextseedsRBGC_redeemed += rng->_stats_nextseedsRBGC_redeemed;
    s->_stats_nextstirs_redeemed    += rng->_stats_nextstirs_redeemed;
    s->_stats_nextseedsbanked       += rng->_stats_nextseedsbanked;
    s->_stats_nextstirs_banked      += rng->_stats_nextstirs_banked;
#endif

    return 0;
}

#endif /* WC_RNG_DEBUG_STATS */


#endif /* WC_NO_RNG */

Coverage Report

Created: 2026-09-28 07:09