/***************************************************************************

 *                                  _   _ ____  _

 *  Project                     ___| | | |  _ \| |

 *                             / __| | | | |_) | |

 *                            | (__| |_| |  _ <| |___

 *                             \___|\___/|_| \_\_____|

 *

 * Copyright (C) Evgeny Grin (Karlson2k), <k2k@narod.ru>.

 *

 * This software is licensed as described in the file COPYING, which

 * you should have received as part of this distribution. The terms

 * are also available at https://curl.se/docs/copyright.html.

 *

 * You may opt to use, copy, modify, merge, publish, distribute and/or sell

 * copies of the Software, and permit persons to whom the Software is

 * furnished to do so, under the terms of the COPYING file.

 *

 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY

 * KIND, either express or implied.

 *

 * SPDX-License-Identifier: curl

 *

 ***************************************************************************/

#include "curl_setup.h"

#if !defined(CURL_DISABLE_DIGEST_AUTH) && !defined(CURL_DISABLE_SHA512_256)

#include "curl_sha512_256.h"

#include "warnless.h"

/* ** This implementation of SHA-512/256 hash calculation was originally ** *

 * ** written by Evgeny Grin (Karlson2k) for GNU libmicrohttpd.          ** *

 * ** The author ported the code to libcurl. The ported code is provided ** *

 * ** under curl license.                                                ** *

 * ** This is a minimal version with minimal optimisations. Performance  ** *

 * ** can be significantly improved. Big-endian store and load macros    ** *

 * ** are obvious targets for optimisation.                              ** */

#ifdef __GNUC__

#  if defined(__has_attribute) && defined(__STDC_VERSION__)

#    if __has_attribute(always_inline) && __STDC_VERSION__ >= 199901

#      define MHDX_INLINE inline __attribute__((always_inline))

#    endif

#  endif

#endif

#if !defined(MHDX_INLINE) && \

  defined(_MSC_VER) && !defined(__GNUC__) && !defined(__clang__)

#  if _MSC_VER >= 1400

#    define MHDX_INLINE __forceinline

#  else

#    define MHDX_INLINE /* empty */

#  endif

#endif

#if !defined(MHDX_INLINE)

#  if defined(inline)

     /* Assume that 'inline' macro was already defined correctly by

      * the build system. */

#    define MHDX_INLINE inline

#  elif defined(__cplusplus)

     /* The code is compiled with C++ compiler.

      * C++ always supports 'inline'. */

#    define MHDX_INLINE inline

#  elif defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901

     /* C99 (and later) supports 'inline' keyword */

#    define MHDX_INLINE inline

#  elif defined(__GNUC__) && __GNUC__ >= 3

     /* GCC supports '__inline__' as an extension */

#    define MHDX_INLINE __inline__

#  else

#    define MHDX_INLINE /* empty */

#  endif

#endif

/* Bits manipulation macros and functions.

   Can be moved to other headers to reuse. */

#define MHDX_GET_64BIT_BE(ptr)                                  \

  ( ((curl_uint64_t)(((const unsigned char*)(ptr))[0]) << 56) | \

    ((curl_uint64_t)(((const unsigned char*)(ptr))[1]) << 48) | \

    ((curl_uint64_t)(((const unsigned char*)(ptr))[2]) << 40) | \

    ((curl_uint64_t)(((const unsigned char*)(ptr))[3]) << 32) | \

    ((curl_uint64_t)(((const unsigned char*)(ptr))[4]) << 24) | \

    ((curl_uint64_t)(((const unsigned char*)(ptr))[5]) << 16) | \

    ((curl_uint64_t)(((const unsigned char*)(ptr))[6]) << 8)  | \

    (curl_uint64_t)(((const unsigned char*)(ptr))[7]) )

#define MHDX_PUT_64BIT_BE(ptr,val) do {                                 \

    ((unsigned char*)(ptr))[7]=(unsigned char)((curl_uint64_t)(val));   \

    ((unsigned char*)(ptr))[6]=(unsigned char)(((curl_uint64_t)(val)) >> 8); \

    ((unsigned char*)(ptr))[5]=(unsigned char)(((curl_uint64_t)(val)) >> 16); \

    ((unsigned char*)(ptr))[4]=(unsigned char)(((curl_uint64_t)(val)) >> 24); \

    ((unsigned char*)(ptr))[3]=(unsigned char)(((curl_uint64_t)(val)) >> 32); \

    ((unsigned char*)(ptr))[2]=(unsigned char)(((curl_uint64_t)(val)) >> 40); \

    ((unsigned char*)(ptr))[1]=(unsigned char)(((curl_uint64_t)(val)) >> 48); \

    ((unsigned char*)(ptr))[0]=(unsigned char)(((curl_uint64_t)(val)) >> 56); \

  } while(0)

/* Defined as a function. The macro version may duplicate the binary code

 * size as each argument is used twice, so if any calculation is used

 * as an argument, the calculation could be done twice. */

static MHDX_INLINE curl_uint64_t

MHDx_rotr64(curl_uint64_t value, unsigned int bits)

{

  bits %= 64;

  if(0 == bits)

    return value;

  /* Defined in a form which modern compiler could optimise. */

  return (value >> bits) | (value << (64 - bits));

}

/* SHA-512/256 specific data */

/**

 * Number of bits in a single SHA-512/256 word.

 */

#define SHA512_256_WORD_SIZE_BITS 64

/**

 * Number of bytes in a single SHA-512/256 word.

 */

#define SHA512_256_BYTES_IN_WORD (SHA512_256_WORD_SIZE_BITS / 8)

/**

 * Hash is kept internally as 8 64-bit words.

 * This is the intermediate hash size, used during computing the final digest.

 */

#define SHA512_256_HASH_SIZE_WORDS 8

/**

 * Size of the SHA-512/256 resulting digest in bytes.

 * This is the final digest size, not intermediate hash.

 */

#define SHA512_256_DIGEST_SIZE_WORDS (SHA512_256_HASH_SIZE_WORDS  / 2)

/**

 * Size of the SHA-512/256 resulting digest in bytes

 * This is the final digest size, not intermediate hash.

 */

#define SHA512_256_DIGEST_SIZE \

  (SHA512_256_DIGEST_SIZE_WORDS * SHA512_256_BYTES_IN_WORD)

/**

 * Size of the SHA-512/256 single processing block in bits.

 */

#define SHA512_256_BLOCK_SIZE_BITS 1024

/**

 * Size of the SHA-512/256 single processing block in bytes.

 */

#define SHA512_256_BLOCK_SIZE (SHA512_256_BLOCK_SIZE_BITS / 8)

/**

 * Size of the SHA-512/256 single processing block in words.

 */

#define SHA512_256_BLOCK_SIZE_WORDS \

  (SHA512_256_BLOCK_SIZE_BITS / SHA512_256_WORD_SIZE_BITS)

/**

 * SHA-512/256 calculation context

 */

struct Sha512_256Ctx

{

  /**

   * Intermediate hash value. The variable is properly aligned. Smart

   * compilers may automatically use fast load/store instruction for big

   * endian data on little endian machine.

   */

  curl_uint64_t H[SHA512_256_HASH_SIZE_WORDS];

  /**

   * SHA-512/256 input data buffer. The buffer is properly aligned. Smart

   * compilers may automatically use fast load/store instruction for big

   * endian data on little endian machine.

   */

  curl_uint64_t buffer[SHA512_256_BLOCK_SIZE_WORDS];

  /**

   * The number of bytes, lower part

   */

  curl_uint64_t count;

  /**

   * The number of bits, high part. Unlike lower part, this counts the number

   * of bits, not bytes.

   */

  curl_uint64_t count_bits_hi;

};

/**

 * Initialise structure for SHA-512/256 calculation.

 *

 * @param context the calculation context

 * @return always CURLE_OK

 */

static CURLcode

MHDx_sha512_256_init(void *context)

{

  struct Sha512_256Ctx *const ctx = (struct Sha512_256Ctx *) context;

  /* Check whether the header and this file use the same numbers */

  DEBUGASSERT(SHA512_256_DIGEST_LENGTH == SHA512_256_DIGEST_SIZE);

  DEBUGASSERT(sizeof(curl_uint64_t) == 8);

  /* Initial hash values, see FIPS PUB 180-4 section 5.3.6.2 */

  /* Values generated by "IV Generation Function" as described in

   * section 5.3.6 */

  ctx->H[0] = CURL_UINT64_C(0x22312194FC2BF72C);

  ctx->H[1] = CURL_UINT64_C(0x9F555FA3C84C64C2);

  ctx->H[2] = CURL_UINT64_C(0x2393B86B6F53B151);

  ctx->H[3] = CURL_UINT64_C(0x963877195940EABD);

  ctx->H[4] = CURL_UINT64_C(0x96283EE2A88EFFE3);

  ctx->H[5] = CURL_UINT64_C(0xBE5E1E2553863992);

  ctx->H[6] = CURL_UINT64_C(0x2B0199FC2C85B8AA);

  ctx->H[7] = CURL_UINT64_C(0x0EB72DDC81C52CA2);

  /* Initialise number of bytes and high part of number of bits. */

  ctx->count = CURL_UINT64_C(0);

  ctx->count_bits_hi = CURL_UINT64_C(0);

  return CURLE_OK;

}

/**

 * Base of the SHA-512/256 transformation.

 * Gets a full 128 bytes block of data and updates hash values;

 * @param H     hash values

 * @param data  the data buffer with #SHA512_256_BLOCK_SIZE bytes block

 */

static void

MHDx_sha512_256_transform(curl_uint64_t H[SHA512_256_HASH_SIZE_WORDS],

                          const void *data)

{

  /* Working variables,

     see FIPS PUB 180-4 section 6.7, 6.4. */

  curl_uint64_t a = H[0];

  curl_uint64_t b = H[1];

  curl_uint64_t c = H[2];

  curl_uint64_t d = H[3];

  curl_uint64_t e = H[4];

  curl_uint64_t f = H[5];

  curl_uint64_t g = H[6];

  curl_uint64_t h = H[7];

  /* Data buffer, used as a cyclic buffer.

     See FIPS PUB 180-4 section 5.2.2, 6.7, 6.4. */

  curl_uint64_t W[16];

  /* 'Ch' and 'Maj' macro functions are defined with widely-used optimisation.

     See FIPS PUB 180-4 formulae 4.8, 4.9. */

#define Ch(x,y,z)     ( (z) ^ ((x) & ((y) ^ (z))) )

#define Maj(x,y,z)    ( ((x) & (y)) ^ ((z) & ((x) ^ (y))) )

  /* Four 'Sigma' macro functions.

     See FIPS PUB 180-4 formulae 4.10, 4.11, 4.12, 4.13. */

#define SIG0(x)                                                         \

  ( MHDx_rotr64((x), 28) ^ MHDx_rotr64((x), 34) ^ MHDx_rotr64((x), 39) )

#define SIG1(x)                                                         \

  ( MHDx_rotr64((x), 14) ^ MHDx_rotr64((x), 18) ^ MHDx_rotr64((x), 41) )

#define sig0(x)                                                 \

  ( MHDx_rotr64((x), 1) ^ MHDx_rotr64((x), 8) ^ ((x) >> 7) )

#define sig1(x)                                                 \

  ( MHDx_rotr64((x), 19) ^ MHDx_rotr64((x), 61) ^ ((x) >> 6) )

  if(1) {

    unsigned int t;

    /* K constants array.

       See FIPS PUB 180-4 section 4.2.3 for K values. */

    static const curl_uint64_t K[80] = {

      CURL_UINT64_C(0x428a2f98d728ae22), CURL_UINT64_C(0x7137449123ef65cd),

      CURL_UINT64_C(0xb5c0fbcfec4d3b2f), CURL_UINT64_C(0xe9b5dba58189dbbc),

      CURL_UINT64_C(0x3956c25bf348b538), CURL_UINT64_C(0x59f111f1b605d019),

      CURL_UINT64_C(0x923f82a4af194f9b), CURL_UINT64_C(0xab1c5ed5da6d8118),

      CURL_UINT64_C(0xd807aa98a3030242), CURL_UINT64_C(0x12835b0145706fbe),

      CURL_UINT64_C(0x243185be4ee4b28c), CURL_UINT64_C(0x550c7dc3d5ffb4e2),

      CURL_UINT64_C(0x72be5d74f27b896f), CURL_UINT64_C(0x80deb1fe3b1696b1),

      CURL_UINT64_C(0x9bdc06a725c71235), CURL_UINT64_C(0xc19bf174cf692694),

      CURL_UINT64_C(0xe49b69c19ef14ad2), CURL_UINT64_C(0xefbe4786384f25e3),

      CURL_UINT64_C(0x0fc19dc68b8cd5b5), CURL_UINT64_C(0x240ca1cc77ac9c65),

      CURL_UINT64_C(0x2de92c6f592b0275), CURL_UINT64_C(0x4a7484aa6ea6e483),

      CURL_UINT64_C(0x5cb0a9dcbd41fbd4), CURL_UINT64_C(0x76f988da831153b5),

      CURL_UINT64_C(0x983e5152ee66dfab), CURL_UINT64_C(0xa831c66d2db43210),

      CURL_UINT64_C(0xb00327c898fb213f), CURL_UINT64_C(0xbf597fc7beef0ee4),

      CURL_UINT64_C(0xc6e00bf33da88fc2), CURL_UINT64_C(0xd5a79147930aa725),

      CURL_UINT64_C(0x06ca6351e003826f), CURL_UINT64_C(0x142929670a0e6e70),

      CURL_UINT64_C(0x27b70a8546d22ffc), CURL_UINT64_C(0x2e1b21385c26c926),

      CURL_UINT64_C(0x4d2c6dfc5ac42aed), CURL_UINT64_C(0x53380d139d95b3df),

      CURL_UINT64_C(0x650a73548baf63de), CURL_UINT64_C(0x766a0abb3c77b2a8),

      CURL_UINT64_C(0x81c2c92e47edaee6), CURL_UINT64_C(0x92722c851482353b),

      CURL_UINT64_C(0xa2bfe8a14cf10364), CURL_UINT64_C(0xa81a664bbc423001),

      CURL_UINT64_C(0xc24b8b70d0f89791), CURL_UINT64_C(0xc76c51a30654be30),

      CURL_UINT64_C(0xd192e819d6ef5218), CURL_UINT64_C(0xd69906245565a910),

      CURL_UINT64_C(0xf40e35855771202a), CURL_UINT64_C(0x106aa07032bbd1b8),

      CURL_UINT64_C(0x19a4c116b8d2d0c8), CURL_UINT64_C(0x1e376c085141ab53),

      CURL_UINT64_C(0x2748774cdf8eeb99), CURL_UINT64_C(0x34b0bcb5e19b48a8),

      CURL_UINT64_C(0x391c0cb3c5c95a63), CURL_UINT64_C(0x4ed8aa4ae3418acb),

      CURL_UINT64_C(0x5b9cca4f7763e373), CURL_UINT64_C(0x682e6ff3d6b2b8a3),

      CURL_UINT64_C(0x748f82ee5defb2fc), CURL_UINT64_C(0x78a5636f43172f60),

      CURL_UINT64_C(0x84c87814a1f0ab72), CURL_UINT64_C(0x8cc702081a6439ec),

      CURL_UINT64_C(0x90befffa23631e28), CURL_UINT64_C(0xa4506cebde82bde9),

      CURL_UINT64_C(0xbef9a3f7b2c67915), CURL_UINT64_C(0xc67178f2e372532b),

      CURL_UINT64_C(0xca273eceea26619c), CURL_UINT64_C(0xd186b8c721c0c207),

      CURL_UINT64_C(0xeada7dd6cde0eb1e), CURL_UINT64_C(0xf57d4f7fee6ed178),

      CURL_UINT64_C(0x06f067aa72176fba), CURL_UINT64_C(0x0a637dc5a2c898a6),

      CURL_UINT64_C(0x113f9804bef90dae), CURL_UINT64_C(0x1b710b35131c471b),

      CURL_UINT64_C(0x28db77f523047d84), CURL_UINT64_C(0x32caab7b40c72493),

      CURL_UINT64_C(0x3c9ebe0a15c9bebc), CURL_UINT64_C(0x431d67c49c100d4c),

      CURL_UINT64_C(0x4cc5d4becb3e42b6), CURL_UINT64_C(0x597f299cfc657e2a),

      CURL_UINT64_C(0x5fcb6fab3ad6faec), CURL_UINT64_C(0x6c44198c4a475817)

    };

    /* One step of SHA-512/256 computation,

       see FIPS PUB 180-4 section 6.4.2 step 3.

       * Note: this macro updates working variables in-place, without rotation.

       * Note: the first (vH += SIG1(vE) + Ch(vE,vF,vG) + kt + wt) equals T1 in

       FIPS PUB 180-4 section 6.4.2 step 3.

       the second (vH += SIG0(vA) + Maj(vE,vF,vC) equals T1 + T2 in

       FIPS PUB 180-4 section 6.4.2 step 3.

       * Note: 'wt' must be used exactly one time in this macro as macro for

       'wt' calculation may change other data as well every time when

       used. */

#define SHA2STEP64(vA,vB,vC,vD,vE,vF,vG,vH,kt,wt) do {                  \

      (vD) += ((vH) += SIG1 ((vE)) + Ch ((vE),(vF),(vG)) + (kt) + (wt)); \

      (vH) += SIG0 ((vA)) + Maj ((vA),(vB),(vC)); } while (0)

    /* One step of SHA-512/256 computation with working variables rotation,

       see FIPS PUB 180-4 section 6.4.2 step 3. This macro version reassigns

       all working variables on each step. */

#define SHA2STEP64RV(vA,vB,vC,vD,vE,vF,vG,vH,kt,wt) do {                \

      curl_uint64_t tmp_h_ = (vH);                                      \

      SHA2STEP64((vA),(vB),(vC),(vD),(vE),(vF),(vG),tmp_h_,(kt),(wt));  \

      (vH) = (vG);                                                      \

      (vG) = (vF);                                                      \

      (vF) = (vE);                                                      \

      (vE) = (vD);                                                      \

      (vD) = (vC);                                                      \

      (vC) = (vB);                                                      \

      (vB) = (vA);                                                      \

      (vA) = tmp_h_;  } while(0)

    /* Get value of W(t) from input data buffer for 0 <= t <= 15,

       See FIPS PUB 180-4 section 6.2.

       Input data must be read in big-endian bytes order,

       see FIPS PUB 180-4 section 3.1.2. */

#define SHA512_GET_W_FROM_DATA(buf,t)                                   \

    MHDX_GET_64BIT_BE(                                                  \

      ((const unsigned char*) (buf)) + (t) * SHA512_256_BYTES_IN_WORD)

    /* During first 16 steps, before making any calculation on each step, the

       W element is read from the input data buffer as a big-endian value and

       stored in the array of W elements. */

    for(t = 0; t < 16; ++t) {

      SHA2STEP64RV(a, b, c, d, e, f, g, h, K[t], \

                   W[t] = SHA512_GET_W_FROM_DATA(data, t));

    }

    /* 'W' generation and assignment for 16 <= t <= 79.

       See FIPS PUB 180-4 section 6.4.2.

       As only the last 16 'W' are used in calculations, it is possible to

       use 16 elements array of W as a cyclic buffer.

       Note: ((t-16) & 15) have same value as (t & 15) */

#define Wgen(w,t)                                                       \

    (curl_uint64_t)( (w)[(t - 16) & 15] + sig1((w)[((t) - 2) & 15])     \

                     + (w)[((t) - 7) & 15] + sig0((w)[((t) - 15) & 15]) )

    /* During the last 64 steps, before making any calculation on each step,

       current W element is generated from other W elements of the cyclic

       buffer and the generated value is stored back in the cyclic buffer. */

    for(t = 16; t < 80; ++t) {

      SHA2STEP64RV(a, b, c, d, e, f, g, h, K[t], \

                   W[t & 15] = Wgen(W, t));

    }

  }

  /* Compute and store the intermediate hash.

     See FIPS PUB 180-4 section 6.4.2 step 4. */

  H[0] += a;

  H[1] += b;

  H[2] += c;

  H[3] += d;

  H[4] += e;

  H[5] += f;

  H[6] += g;

  H[7] += h;

}

/**

 * Process portion of bytes.

 *

 * @param context the calculation context

 * @param data bytes to add to hash

 * @param length number of bytes in @a data

 */

static void

MHDx_sha512_256_update(void *context,

                       const unsigned char *data,

                       unsigned int length)

{

  unsigned int bytes_have; /**< Number of bytes in the context buffer */

  struct Sha512_256Ctx *const ctx = (struct Sha512_256Ctx *) context;

  /* the void pointer here is required to mute Intel compiler warning */

  void *const ctx_buf = ctx->buffer;

  DEBUGASSERT((data != NULL) || (length == 0));

  if(0 == length)

    return; /* Shortcut, do nothing */

  /* Note: (count & (SHA512_256_BLOCK_SIZE-1))

     equals (count % SHA512_256_BLOCK_SIZE) for this block size. */

  bytes_have = (unsigned int) (ctx->count & (SHA512_256_BLOCK_SIZE - 1));

  ctx->count += length;

  if(length > ctx->count)

    ctx->count_bits_hi += 1U << 3; /* Value wrap */

  ctx->count_bits_hi += ctx->count >> 61;

  ctx->count &= CURL_UINT64_C(0x1FFFFFFFFFFFFFFF);

  if(0 != bytes_have) {

    unsigned int bytes_left = SHA512_256_BLOCK_SIZE - bytes_have;

    if(length >= bytes_left) {

      /* Combine new data with data in the buffer and process the full

         block. */

      memcpy(((unsigned char *) ctx_buf) + bytes_have,

             data,

             bytes_left);

      data += bytes_left;

      length -= bytes_left;

      MHDx_sha512_256_transform(ctx->H, ctx->buffer);

      bytes_have = 0;

    }

  }

  while(SHA512_256_BLOCK_SIZE <= length) {

    /* Process any full blocks of new data directly,

       without copying to the buffer. */

    MHDx_sha512_256_transform(ctx->H, data);

    data += SHA512_256_BLOCK_SIZE;

    length -= SHA512_256_BLOCK_SIZE;

  }

  if(0 != length) {

    /* Copy incomplete block of new data (if any)

       to the buffer. */

    memcpy(((unsigned char *) ctx_buf) + bytes_have, data, length);

  }

}

/**

 * Size of "length" insertion in bits.

 * See FIPS PUB 180-4 section 5.1.2.

 */

#define SHA512_256_SIZE_OF_LEN_ADD_BITS 128

/**

 * Size of "length" insertion in bytes.

 */

#define SHA512_256_SIZE_OF_LEN_ADD (SHA512_256_SIZE_OF_LEN_ADD_BITS / 8)

/**

 * Finalise SHA-512/256 calculation, return digest.

 *

 * @param context the calculation context

 * @param[out] digest set to the hash, must be #SHA512_256_DIGEST_SIZE bytes

 */

static void

MHDx_sha512_256_finish(unsigned char *digest,

                       void *context)

{

  struct Sha512_256Ctx *const ctx = (struct Sha512_256Ctx *) context;

  curl_uint64_t num_bits;   /**< Number of processed bits */

  unsigned int bytes_have; /**< Number of bytes in the context buffer */

  /* the void pointer here is required to mute Intel compiler warning */

  void *const ctx_buf = ctx->buffer;

  /* Memorise the number of processed bits.

     The padding and other data added here during the postprocessing must

     not change the amount of hashed data. */

  num_bits = ctx->count << 3;

  /* Note: (count & (SHA512_256_BLOCK_SIZE-1))

           equals (count % SHA512_256_BLOCK_SIZE) for this block size. */

  bytes_have = (unsigned int) (ctx->count & (SHA512_256_BLOCK_SIZE - 1));

  /* Input data must be padded with a single bit "1", then with zeros and

     the finally the length of data in bits must be added as the final bytes

     of the last block.

     See FIPS PUB 180-4 section 5.1.2. */

  /* Data is always processed in form of bytes (not by individual bits),

     therefore position of the first padding bit in byte is always

     predefined (0x80). */

  /* Buffer always have space at least for one byte (as full buffers are

     processed when formed). */

  ((unsigned char *) ctx_buf)[bytes_have++] = 0x80U;

  if(SHA512_256_BLOCK_SIZE - bytes_have < SHA512_256_SIZE_OF_LEN_ADD) {

    /* No space in the current block to put the total length of message.

       Pad the current block with zeros and process it. */

    if(bytes_have < SHA512_256_BLOCK_SIZE)

      memset(((unsigned char *) ctx_buf) + bytes_have, 0,

             SHA512_256_BLOCK_SIZE - bytes_have);

    /* Process the full block. */

    MHDx_sha512_256_transform(ctx->H, ctx->buffer);

    /* Start the new block. */

    bytes_have = 0;

  }

  /* Pad the rest of the buffer with zeros. */

  memset(((unsigned char *) ctx_buf) + bytes_have, 0,

         SHA512_256_BLOCK_SIZE - SHA512_256_SIZE_OF_LEN_ADD - bytes_have);

  /* Put high part of number of bits in processed message and then lower

     part of number of bits as big-endian values.

     See FIPS PUB 180-4 section 5.1.2. */

  /* Note: the target location is predefined and buffer is always aligned */

  MHDX_PUT_64BIT_BE(((unsigned char *) ctx_buf)  \

                      + SHA512_256_BLOCK_SIZE         \

                      - SHA512_256_SIZE_OF_LEN_ADD,   \

                      ctx->count_bits_hi);

  MHDX_PUT_64BIT_BE(((unsigned char *) ctx_buf)      \

                      + SHA512_256_BLOCK_SIZE             \

                      - SHA512_256_SIZE_OF_LEN_ADD        \

                      + SHA512_256_BYTES_IN_WORD,         \

                      num_bits);

  /* Process the full final block. */

  MHDx_sha512_256_transform(ctx->H, ctx->buffer);

  /* Put in BE mode the leftmost part of the hash as the final digest.

     See FIPS PUB 180-4 section 6.7. */

  MHDX_PUT_64BIT_BE((digest + 0 * SHA512_256_BYTES_IN_WORD), ctx->H[0]);

  MHDX_PUT_64BIT_BE((digest + 1 * SHA512_256_BYTES_IN_WORD), ctx->H[1]);

  MHDX_PUT_64BIT_BE((digest + 2 * SHA512_256_BYTES_IN_WORD), ctx->H[2]);

  MHDX_PUT_64BIT_BE((digest + 3 * SHA512_256_BYTES_IN_WORD), ctx->H[3]);

  /* Erase potentially sensitive data. */

  memset(ctx, 0, sizeof(struct Sha512_256Ctx));

}

/**

 * Compute SHA-512/256 hash for the given data in one function call

 * @param[out] output the pointer to put the hash

 * @param[in] input the pointer to the data to process

 * @param input_size the size of the data pointed by @a input

 * @return always #CURLE_OK

 */

CURLcode

Curl_sha512_256it(unsigned char *output, const unsigned char *input,

                  size_t input_size)

{

  struct Sha512_256Ctx ctx;

  static const unsigned int max_step_size = (unsigned int)(-1);

  (void) MHDx_sha512_256_init(&ctx); /* Always succeed */

  while(input_size >= max_step_size) {

    MHDx_sha512_256_update(&ctx, (const void *) input, max_step_size);

    input += max_step_size;

    input_size -= max_step_size;

  }

  MHDx_sha512_256_update(&ctx, (const void *) input,

                          curlx_uztoui(input_size));

  MHDx_sha512_256_finish(output, &ctx);

  return CURLE_OK;

}

const struct HMAC_params Curl_HMAC_SHA512_256[] = {

  {

    /* Initialize context procedure. */

    MHDx_sha512_256_init,

    /* Update context with data. */

    MHDx_sha512_256_update,

    /* Get final result procedure. */

    MHDx_sha512_256_finish,

    /* Context structure size. */

    sizeof(struct Sha512_256Ctx),

    /* Maximum key length (bytes). */

    SHA512_256_BLOCK_SIZE,

    /* Result length (bytes). */

    SHA512_256_DIGEST_SIZE

  }

};

#endif /* !CURL_DISABLE_DIGEST_AUTH && !CURL_DISABLE_SHA512_256 */