/*

 * Copyright 2020-2023 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the Apache License 2.0 (the "License").  You may not use

 * this file except in compliance with the License.  You can obtain a copy

 * in the file LICENSE in the source distribution or at

 * https://www.openssl.org/source/license.html

 */

#include <stdio.h>

#include <stdlib.h>

#include <openssl/evp.h>

#include <openssl/rand.h>

#include <openssl/core.h>

#include <openssl/core_names.h>

#include <openssl/crypto.h>

#include "internal/cryptlib.h"

#include "internal/numbers.h"

#include "internal/provider.h"

#include "internal/core.h"

#include "crypto/evp.h"

#include "evp_local.h"

struct evp_rand_st {

    OSSL_PROVIDER *prov;

    int name_id;

    char *type_name;

    const char *description;

    CRYPTO_REF_COUNT refcnt;

    const OSSL_DISPATCH *dispatch;

    OSSL_FUNC_rand_newctx_fn *newctx;

    OSSL_FUNC_rand_freectx_fn *freectx;

    OSSL_FUNC_rand_instantiate_fn *instantiate;

    OSSL_FUNC_rand_uninstantiate_fn *uninstantiate;

    OSSL_FUNC_rand_generate_fn *generate;

    OSSL_FUNC_rand_reseed_fn *reseed;

    OSSL_FUNC_rand_nonce_fn *nonce;

    OSSL_FUNC_rand_enable_locking_fn *enable_locking;

    OSSL_FUNC_rand_lock_fn *lock;

    OSSL_FUNC_rand_unlock_fn *unlock;

    OSSL_FUNC_rand_gettable_params_fn *gettable_params;

    OSSL_FUNC_rand_gettable_ctx_params_fn *gettable_ctx_params;

    OSSL_FUNC_rand_settable_ctx_params_fn *settable_ctx_params;

    OSSL_FUNC_rand_get_params_fn *get_params;

    OSSL_FUNC_rand_get_ctx_params_fn *get_ctx_params;

    OSSL_FUNC_rand_set_ctx_params_fn *set_ctx_params;

    OSSL_FUNC_rand_verify_zeroization_fn *verify_zeroization;

    OSSL_FUNC_rand_get_seed_fn *get_seed;

    OSSL_FUNC_rand_clear_seed_fn *clear_seed;

} /* EVP_RAND */ ;

static int evp_rand_up_ref(void *vrand)

{

    EVP_RAND *rand = (EVP_RAND *)vrand;

    int ref = 0;

    if (rand != NULL)

        return CRYPTO_UP_REF(&rand->refcnt, &ref);

    return 1;

}

static void evp_rand_free(void *vrand)

{

    EVP_RAND *rand = (EVP_RAND *)vrand;

    int ref = 0;

    if (rand == NULL)

        return;

    CRYPTO_DOWN_REF(&rand->refcnt, &ref);

    if (ref > 0)

        return;

    OPENSSL_free(rand->type_name);

    ossl_provider_free(rand->prov);

    CRYPTO_FREE_REF(&rand->refcnt);

    OPENSSL_free(rand);

}

static void *evp_rand_new(void)

{

    EVP_RAND *rand = OPENSSL_zalloc(sizeof(*rand));

    if (rand == NULL)

        return NULL;

    if (!CRYPTO_NEW_REF(&rand->refcnt, 1)) {

        OPENSSL_free(rand);

        return NULL;

    }

    return rand;

}

/* Enable locking of the underlying DRBG/RAND if available */

int EVP_RAND_enable_locking(EVP_RAND_CTX *rand)

{

    if (rand->meth->enable_locking != NULL)

        return rand->meth->enable_locking(rand->algctx);

    ERR_raise(ERR_LIB_EVP, EVP_R_LOCKING_NOT_SUPPORTED);

    return 0;

}

/* Lock the underlying DRBG/RAND if available */

static int evp_rand_lock(EVP_RAND_CTX *rand)

{

    if (rand->meth->lock != NULL)

        return rand->meth->lock(rand->algctx);

    return 1;

}

/* Unlock the underlying DRBG/RAND if available */

static void evp_rand_unlock(EVP_RAND_CTX *rand)

{

    if (rand->meth->unlock != NULL)

        rand->meth->unlock(rand->algctx);

}

static void *evp_rand_from_algorithm(int name_id,

                                     const OSSL_ALGORITHM *algodef,

                                     OSSL_PROVIDER *prov)

{

    const OSSL_DISPATCH *fns = algodef->implementation;

    EVP_RAND *rand = NULL;

    int fnrandcnt = 0, fnctxcnt = 0, fnlockcnt = 0, fnenablelockcnt = 0;

#ifdef FIPS_MODULE

    int fnzeroizecnt = 0;

#endif

    if ((rand = evp_rand_new()) == NULL) {

        ERR_raise(ERR_LIB_EVP, ERR_R_EVP_LIB);

        return NULL;

    }

    rand->name_id = name_id;

    if ((rand->type_name = ossl_algorithm_get1_first_name(algodef)) == NULL) {

        evp_rand_free(rand);

        return NULL;

    }

    rand->description = algodef->algorithm_description;

    rand->dispatch = fns;

    for (; fns->function_id != 0; fns++) {

        switch (fns->function_id) {

        case OSSL_FUNC_RAND_NEWCTX:

            if (rand->newctx != NULL)

                break;

            rand->newctx = OSSL_FUNC_rand_newctx(fns);

            fnctxcnt++;

            break;

        case OSSL_FUNC_RAND_FREECTX:

            if (rand->freectx != NULL)

                break;

            rand->freectx = OSSL_FUNC_rand_freectx(fns);

            fnctxcnt++;

            break;

        case OSSL_FUNC_RAND_INSTANTIATE:

            if (rand->instantiate != NULL)

                break;

            rand->instantiate = OSSL_FUNC_rand_instantiate(fns);

            fnrandcnt++;

            break;

        case OSSL_FUNC_RAND_UNINSTANTIATE:

             if (rand->uninstantiate != NULL)

                break;

            rand->uninstantiate = OSSL_FUNC_rand_uninstantiate(fns);

            fnrandcnt++;

            break;

        case OSSL_FUNC_RAND_GENERATE:

            if (rand->generate != NULL)

                break;

            rand->generate = OSSL_FUNC_rand_generate(fns);

            fnrandcnt++;

            break;

        case OSSL_FUNC_RAND_RESEED:

            if (rand->reseed != NULL)

                break;

            rand->reseed = OSSL_FUNC_rand_reseed(fns);

            break;

        case OSSL_FUNC_RAND_NONCE:

            if (rand->nonce != NULL)

                break;

            rand->nonce = OSSL_FUNC_rand_nonce(fns);

            break;

        case OSSL_FUNC_RAND_ENABLE_LOCKING:

            if (rand->enable_locking != NULL)

                break;

            rand->enable_locking = OSSL_FUNC_rand_enable_locking(fns);

            fnenablelockcnt++;

            break;

        case OSSL_FUNC_RAND_LOCK:

            if (rand->lock != NULL)

                break;

            rand->lock = OSSL_FUNC_rand_lock(fns);

            fnlockcnt++;

            break;

        case OSSL_FUNC_RAND_UNLOCK:

            if (rand->unlock != NULL)

                break;

            rand->unlock = OSSL_FUNC_rand_unlock(fns);

            fnlockcnt++;

            break;

        case OSSL_FUNC_RAND_GETTABLE_PARAMS:

            if (rand->gettable_params != NULL)

                break;

            rand->gettable_params =

                OSSL_FUNC_rand_gettable_params(fns);

            break;

        case OSSL_FUNC_RAND_GETTABLE_CTX_PARAMS:

            if (rand->gettable_ctx_params != NULL)

                break;

            rand->gettable_ctx_params =

                OSSL_FUNC_rand_gettable_ctx_params(fns);

            break;

        case OSSL_FUNC_RAND_SETTABLE_CTX_PARAMS:

            if (rand->settable_ctx_params != NULL)

                break;

            rand->settable_ctx_params =

                OSSL_FUNC_rand_settable_ctx_params(fns);

            break;

        case OSSL_FUNC_RAND_GET_PARAMS:

            if (rand->get_params != NULL)

                break;

            rand->get_params = OSSL_FUNC_rand_get_params(fns);

            break;

        case OSSL_FUNC_RAND_GET_CTX_PARAMS:

            if (rand->get_ctx_params != NULL)

                break;

            rand->get_ctx_params = OSSL_FUNC_rand_get_ctx_params(fns);

            fnctxcnt++;

            break;

        case OSSL_FUNC_RAND_SET_CTX_PARAMS:

            if (rand->set_ctx_params != NULL)

                break;

            rand->set_ctx_params = OSSL_FUNC_rand_set_ctx_params(fns);

            break;

        case OSSL_FUNC_RAND_VERIFY_ZEROIZATION:

            if (rand->verify_zeroization != NULL)

                break;

            rand->verify_zeroization = OSSL_FUNC_rand_verify_zeroization(fns);

#ifdef FIPS_MODULE

            fnzeroizecnt++;

#endif

            break;

        case OSSL_FUNC_RAND_GET_SEED:

            if (rand->get_seed != NULL)

                break;

            rand->get_seed = OSSL_FUNC_rand_get_seed(fns);

            break;

        case OSSL_FUNC_RAND_CLEAR_SEED:

            if (rand->clear_seed != NULL)

                break;

            rand->clear_seed = OSSL_FUNC_rand_clear_seed(fns);

            break;

        }

    }

    /*

     * In order to be a consistent set of functions we must have at least

     * a complete set of "rand" functions and a complete set of context

     * management functions.  In FIPS mode, we also require the zeroization

     * verification function.

     *

     * In addition, if locking can be enabled, we need a complete set of

     * locking functions.

     */

    if (fnrandcnt != 3

            || fnctxcnt != 3

            || (fnenablelockcnt != 0 && fnenablelockcnt != 1)

            || (fnlockcnt != 0 && fnlockcnt != 2)

#ifdef FIPS_MODULE

            || fnzeroizecnt != 1

#endif

       ) {

        evp_rand_free(rand);

        ERR_raise(ERR_LIB_EVP, EVP_R_INVALID_PROVIDER_FUNCTIONS);

        return NULL;

    }

    if (prov != NULL && !ossl_provider_up_ref(prov)) {

        evp_rand_free(rand);

        ERR_raise(ERR_LIB_EVP, ERR_R_INTERNAL_ERROR);

        return NULL;

    }

    rand->prov = prov;

    return rand;

}

EVP_RAND *EVP_RAND_fetch(OSSL_LIB_CTX *libctx, const char *algorithm,

                         const char *properties)

{

    return evp_generic_fetch(libctx, OSSL_OP_RAND, algorithm, properties,

                             evp_rand_from_algorithm, evp_rand_up_ref,

                             evp_rand_free);

}

int EVP_RAND_up_ref(EVP_RAND *rand)

{

    return evp_rand_up_ref(rand);

}

void EVP_RAND_free(EVP_RAND *rand)

{

    evp_rand_free(rand);

}

int evp_rand_get_number(const EVP_RAND *rand)

{

    return rand->name_id;

}

const char *EVP_RAND_get0_name(const EVP_RAND *rand)

{

    return rand->type_name;

}

const char *EVP_RAND_get0_description(const EVP_RAND *rand)

{

    return rand->description;

}

int EVP_RAND_is_a(const EVP_RAND *rand, const char *name)

{

    return rand != NULL && evp_is_a(rand->prov, rand->name_id, NULL, name);

}

const OSSL_PROVIDER *EVP_RAND_get0_provider(const EVP_RAND *rand)

{

    return rand->prov;

}

int EVP_RAND_get_params(EVP_RAND *rand, OSSL_PARAM params[])

{

    if (rand->get_params != NULL)

        return rand->get_params(params);

    return 1;

}

int EVP_RAND_CTX_up_ref(EVP_RAND_CTX *ctx)

{

    int ref = 0;

    return CRYPTO_UP_REF(&ctx->refcnt, &ref);

}

EVP_RAND_CTX *EVP_RAND_CTX_new(EVP_RAND *rand, EVP_RAND_CTX *parent)

{

    EVP_RAND_CTX *ctx;

    void *parent_ctx = NULL;

    const OSSL_DISPATCH *parent_dispatch = NULL;

    if (rand == NULL) {

        ERR_raise(ERR_LIB_EVP, EVP_R_INVALID_NULL_ALGORITHM);

        return NULL;

    }

    ctx = OPENSSL_zalloc(sizeof(*ctx));

    if (ctx == NULL)

        return NULL;

    if (!CRYPTO_NEW_REF(&ctx->refcnt, 1)) {

        OPENSSL_free(ctx);

        return NULL;

    }

    if (parent != NULL) {

        if (!EVP_RAND_CTX_up_ref(parent)) {

            ERR_raise(ERR_LIB_EVP, ERR_R_INTERNAL_ERROR);

            CRYPTO_FREE_REF(&ctx->refcnt);

            OPENSSL_free(ctx);

            return NULL;

        }

        parent_ctx = parent->algctx;

        parent_dispatch = parent->meth->dispatch;

    }

    if ((ctx->algctx = rand->newctx(ossl_provider_ctx(rand->prov), parent_ctx,

                                    parent_dispatch)) == NULL

            || !EVP_RAND_up_ref(rand)) {

        ERR_raise(ERR_LIB_EVP, ERR_R_EVP_LIB);

        rand->freectx(ctx->algctx);

        CRYPTO_FREE_REF(&ctx->refcnt);

        OPENSSL_free(ctx);

        EVP_RAND_CTX_free(parent);

        return NULL;

    }

    ctx->meth = rand;

    ctx->parent = parent;

    return ctx;

}

void EVP_RAND_CTX_free(EVP_RAND_CTX *ctx)

{

    int ref = 0;

    EVP_RAND_CTX *parent;

    if (ctx == NULL)

        return;

    CRYPTO_DOWN_REF(&ctx->refcnt, &ref);

    if (ref > 0)

        return;

    parent = ctx->parent;

    ctx->meth->freectx(ctx->algctx);

    ctx->algctx = NULL;

    EVP_RAND_free(ctx->meth);

    CRYPTO_FREE_REF(&ctx->refcnt);

    OPENSSL_free(ctx);

    EVP_RAND_CTX_free(parent);

}

EVP_RAND *EVP_RAND_CTX_get0_rand(EVP_RAND_CTX *ctx)

{

    return ctx->meth;

}

static int evp_rand_get_ctx_params_locked(EVP_RAND_CTX *ctx,

                                          OSSL_PARAM params[])

{

    return ctx->meth->get_ctx_params(ctx->algctx, params);

}

int EVP_RAND_CTX_get_params(EVP_RAND_CTX *ctx, OSSL_PARAM params[])

{

    int res;

    if (!evp_rand_lock(ctx))

        return 0;

    res = evp_rand_get_ctx_params_locked(ctx, params);

    evp_rand_unlock(ctx);

    return res;

}

static int evp_rand_set_ctx_params_locked(EVP_RAND_CTX *ctx,

                                          const OSSL_PARAM params[])

{

    if (ctx->meth->set_ctx_params != NULL)

        return ctx->meth->set_ctx_params(ctx->algctx, params);

    return 1;

}

int EVP_RAND_CTX_set_params(EVP_RAND_CTX *ctx, const OSSL_PARAM params[])

{

    int res;

    if (!evp_rand_lock(ctx))

        return 0;

    res = evp_rand_set_ctx_params_locked(ctx, params);

    evp_rand_unlock(ctx);

    return res;

}

const OSSL_PARAM *EVP_RAND_gettable_params(const EVP_RAND *rand)

{

    if (rand->gettable_params == NULL)

        return NULL;

    return rand->gettable_params(ossl_provider_ctx(EVP_RAND_get0_provider(rand)));

}

const OSSL_PARAM *EVP_RAND_gettable_ctx_params(const EVP_RAND *rand)

{

    void *provctx;

    if (rand->gettable_ctx_params == NULL)

        return NULL;

    provctx = ossl_provider_ctx(EVP_RAND_get0_provider(rand));

    return rand->gettable_ctx_params(NULL, provctx);

}

const OSSL_PARAM *EVP_RAND_settable_ctx_params(const EVP_RAND *rand)

{

    void *provctx;

    if (rand->settable_ctx_params == NULL)

        return NULL;

    provctx = ossl_provider_ctx(EVP_RAND_get0_provider(rand));

    return rand->settable_ctx_params(NULL, provctx);

}

const OSSL_PARAM *EVP_RAND_CTX_gettable_params(EVP_RAND_CTX *ctx)

{

    void *provctx;

    if (ctx->meth->gettable_ctx_params == NULL)

        return NULL;

    provctx = ossl_provider_ctx(EVP_RAND_get0_provider(ctx->meth));

    return ctx->meth->gettable_ctx_params(ctx->algctx, provctx);

}

const OSSL_PARAM *EVP_RAND_CTX_settable_params(EVP_RAND_CTX *ctx)

{

    void *provctx;

    if (ctx->meth->settable_ctx_params == NULL)

        return NULL;

    provctx = ossl_provider_ctx(EVP_RAND_get0_provider(ctx->meth));

    return ctx->meth->settable_ctx_params(ctx->algctx, provctx);

}

void EVP_RAND_do_all_provided(OSSL_LIB_CTX *libctx,

                              void (*fn)(EVP_RAND *rand, void *arg),

                              void *arg)

{

    evp_generic_do_all(libctx, OSSL_OP_RAND,

                       (void (*)(void *, void *))fn, arg,

                       evp_rand_from_algorithm, evp_rand_up_ref,

                       evp_rand_free);

}

int EVP_RAND_names_do_all(const EVP_RAND *rand,

                          void (*fn)(const char *name, void *data),

                          void *data)

{

    if (rand->prov != NULL)

        return evp_names_do_all(rand->prov, rand->name_id, fn, data);

    return 1;

}

static int evp_rand_instantiate_locked

    (EVP_RAND_CTX *ctx, unsigned int strength, int prediction_resistance,

     const unsigned char *pstr, size_t pstr_len, const OSSL_PARAM params[])

{

    return ctx->meth->instantiate(ctx->algctx, strength, prediction_resistance,

                                  pstr, pstr_len, params);

}

int EVP_RAND_instantiate(EVP_RAND_CTX *ctx, unsigned int strength,

                         int prediction_resistance,

                         const unsigned char *pstr, size_t pstr_len,

                         const OSSL_PARAM params[])

{

    int res;

    if (!evp_rand_lock(ctx))

        return 0;

    res = evp_rand_instantiate_locked(ctx, strength, prediction_resistance,

                                      pstr, pstr_len, params);

    evp_rand_unlock(ctx);

    return res;

}

static int evp_rand_uninstantiate_locked(EVP_RAND_CTX *ctx)

{

    return ctx->meth->uninstantiate(ctx->algctx);

}

int EVP_RAND_uninstantiate(EVP_RAND_CTX *ctx)

{

    int res;

    if (!evp_rand_lock(ctx))

        return 0;

    res = evp_rand_uninstantiate_locked(ctx);

    evp_rand_unlock(ctx);

    return res;

}

static int evp_rand_generate_locked(EVP_RAND_CTX *ctx, unsigned char *out,

                                    size_t outlen, unsigned int strength,

                                    int prediction_resistance,

                                    const unsigned char *addin,

                                    size_t addin_len)

{

    size_t chunk, max_request = 0;

    OSSL_PARAM params[2] = { OSSL_PARAM_END, OSSL_PARAM_END };

    params[0] = OSSL_PARAM_construct_size_t(OSSL_RAND_PARAM_MAX_REQUEST,

                                            &max_request);

    if (!evp_rand_get_ctx_params_locked(ctx, params)

            || max_request == 0) {

        ERR_raise(ERR_LIB_EVP, EVP_R_UNABLE_TO_GET_MAXIMUM_REQUEST_SIZE);

        return 0;

    }

    for (; outlen > 0; outlen -= chunk, out += chunk) {

        chunk = outlen > max_request ? max_request : outlen;

        if (!ctx->meth->generate(ctx->algctx, out, chunk, strength,

                                 prediction_resistance, addin, addin_len)) {

            ERR_raise(ERR_LIB_EVP, EVP_R_GENERATE_ERROR);

            return 0;

        }

        /*

         * Prediction resistance is only relevant the first time around,

         * subsequently, the DRBG has already been properly reseeded.

         */

        prediction_resistance = 0;

    }

    return 1;

}

int EVP_RAND_generate(EVP_RAND_CTX *ctx, unsigned char *out, size_t outlen,

                      unsigned int strength, int prediction_resistance,

                      const unsigned char *addin, size_t addin_len)

{

    int res;

    if (!evp_rand_lock(ctx))

        return 0;

    res = evp_rand_generate_locked(ctx, out, outlen, strength,

                                   prediction_resistance, addin, addin_len);

    evp_rand_unlock(ctx);

    return res;

}

static int evp_rand_reseed_locked(EVP_RAND_CTX *ctx, int prediction_resistance,

                                  const unsigned char *ent, size_t ent_len,

                                  const unsigned char *addin, size_t addin_len)

{

    if (ctx->meth->reseed != NULL)

        return ctx->meth->reseed(ctx->algctx, prediction_resistance,

                                 ent, ent_len, addin, addin_len);

    return 1;

}

int EVP_RAND_reseed(EVP_RAND_CTX *ctx, int prediction_resistance,

                    const unsigned char *ent, size_t ent_len,

                    const unsigned char *addin, size_t addin_len)

{

    int res;

    if (!evp_rand_lock(ctx))

        return 0;

    res = evp_rand_reseed_locked(ctx, prediction_resistance,

                                 ent, ent_len, addin, addin_len);

    evp_rand_unlock(ctx);

    return res;

}

static unsigned int evp_rand_strength_locked(EVP_RAND_CTX *ctx)

{

    OSSL_PARAM params[2] = { OSSL_PARAM_END, OSSL_PARAM_END };

    unsigned int strength = 0;

    params[0] = OSSL_PARAM_construct_uint(OSSL_RAND_PARAM_STRENGTH, &strength);

    if (!evp_rand_get_ctx_params_locked(ctx, params))

        return 0;

    return strength;

}

unsigned int EVP_RAND_get_strength(EVP_RAND_CTX *ctx)

{

    unsigned int res;

    if (!evp_rand_lock(ctx))

        return 0;

    res = evp_rand_strength_locked(ctx);

    evp_rand_unlock(ctx);

    return res;

}

static int evp_rand_nonce_locked(EVP_RAND_CTX *ctx, unsigned char *out,

                                 size_t outlen)

{

    unsigned int str = evp_rand_strength_locked(ctx);

    if (ctx->meth->nonce != NULL)

        return ctx->meth->nonce(ctx->algctx, out, str, outlen, outlen) > 0;

    return evp_rand_generate_locked(ctx, out, outlen, str, 0, NULL, 0);

}

int EVP_RAND_nonce(EVP_RAND_CTX *ctx, unsigned char *out, size_t outlen)

{

    int res;

    if (ctx == NULL || out == NULL || outlen == 0) {

        ERR_raise(ERR_LIB_EVP, ERR_R_PASSED_NULL_PARAMETER);

        return 0;

    }

    if (!evp_rand_lock(ctx))

        return 0;

    res = evp_rand_nonce_locked(ctx, out, outlen);

    evp_rand_unlock(ctx);

    return res;

}

int EVP_RAND_get_state(EVP_RAND_CTX *ctx)

{

    OSSL_PARAM params[2] = { OSSL_PARAM_END, OSSL_PARAM_END };

    int state;

    params[0] = OSSL_PARAM_construct_int(OSSL_RAND_PARAM_STATE, &state);

    if (!EVP_RAND_CTX_get_params(ctx, params))

        state = EVP_RAND_STATE_ERROR;

    return state;

}

static int evp_rand_verify_zeroization_locked(EVP_RAND_CTX *ctx)

{

    if (ctx->meth->verify_zeroization != NULL)

        return ctx->meth->verify_zeroization(ctx->algctx);

    return 0;

}

int EVP_RAND_verify_zeroization(EVP_RAND_CTX *ctx)

{

    int res;

    if (!evp_rand_lock(ctx))

        return 0;

    res = evp_rand_verify_zeroization_locked(ctx);

    evp_rand_unlock(ctx);

    return res;

}

int evp_rand_can_seed(EVP_RAND_CTX *ctx)

{

    return ctx->meth->get_seed != NULL;

}

static size_t evp_rand_get_seed_locked(EVP_RAND_CTX *ctx,

                                       unsigned char **buffer,

                                       int entropy,

                                       size_t min_len, size_t max_len,

                                       int prediction_resistance,

                                       const unsigned char *adin,

                                       size_t adin_len)

{

    if (ctx->meth->get_seed != NULL)

        return ctx->meth->get_seed(ctx->algctx, buffer,

                                   entropy, min_len, max_len,

                                   prediction_resistance,

                                   adin, adin_len);

    return 0;

}

size_t evp_rand_get_seed(EVP_RAND_CTX *ctx,

                         unsigned char **buffer,

                         int entropy, size_t min_len, size_t max_len,

                         int prediction_resistance,

                         const unsigned char *adin, size_t adin_len)

{

    int res;

    if (!evp_rand_lock(ctx))

        return 0;

    res = evp_rand_get_seed_locked(ctx,

                                   buffer,

                                   entropy, min_len, max_len,

                                   prediction_resistance,

                                   adin, adin_len);

    evp_rand_unlock(ctx);

    return res;

}

static void evp_rand_clear_seed_locked(EVP_RAND_CTX *ctx,

                                       unsigned char *buffer, size_t b_len)

{

    if (ctx->meth->clear_seed != NULL)

        ctx->meth->clear_seed(ctx->algctx, buffer, b_len);

}

void evp_rand_clear_seed(EVP_RAND_CTX *ctx,

                         unsigned char *buffer, size_t b_len)

{

    if (!evp_rand_lock(ctx))

        return;

    evp_rand_clear_seed_locked(ctx, buffer, b_len);

    evp_rand_unlock(ctx);

}