/*

  This file is part of GNU libmicrohttpd

  Copyright (C) 2019-2024 Evgeny Grin (Karlson2k)

  GNU libmicrohttpd is free software; you can redistribute it and/or

  modify it under the terms of the GNU Lesser General Public

  License as published by the Free Software Foundation; either

  version 2.1 of the License, or (at your option) any later version.

  GNU libmicrohttpd 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

  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public

  License along with this library; if not, write to the Free Software

  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

*/

/**

 * @file src/mhd2/sha256.c

 * @brief  Calculation of SHA-256 digest as defined in FIPS PUB 180-4 (2015)

 * @author Karlson2k (Evgeny Grin)

 */

#include "mhd_sys_options.h"

#include "sys_bool_type.h"

#include <string.h>

#include "mhd_bithelpers.h"

#include "mhd_assert.h"

#include "sha256_int.h"

MHD_INTERNAL void MHD_FN_PAR_NONNULL_ALL_

mhd_SHA256_init (struct mhd_Sha256CtxInt *ctx)

{

  /* Initial hash values, see FIPS PUB 180-4 paragraph 5.3.3 */

  /* First thirty-two bits of the fractional parts of the square

   * roots of the first eight prime numbers: 2, 3, 5, 7, 11, 13,

   * 17, 19." */

  ctx->H[0] = UINT32_C (0x6a09e667);

  ctx->H[1] = UINT32_C (0xbb67ae85);

  ctx->H[2] = UINT32_C (0x3c6ef372);

  ctx->H[3] = UINT32_C (0xa54ff53a);

  ctx->H[4] = UINT32_C (0x510e527f);

  ctx->H[5] = UINT32_C (0x9b05688c);

  ctx->H[6] = UINT32_C (0x1f83d9ab);

  ctx->H[7] = UINT32_C (0x5be0cd19);

  /* Initialise number of bytes. */

  ctx->count = 0;

}

mhd_DATA_TRUNCATION_RUNTIME_CHECK_DISABLE

static MHD_FN_PAR_NONNULL_ALL_ void

sha256_transform (uint32_t H[mhd_SHA256_DIGEST_SIZE_WORDS],

                  const void *restrict data)

{

  /* Working variables,

     see FIPS PUB 180-4 paragraph 6.2. */

  uint32_t a = H[0];

  uint32_t b = H[1];

  uint32_t c = H[2];

  uint32_t d = H[3];

  uint32_t e = H[4];

  uint32_t f = H[5];

  uint32_t g = H[6];

  uint32_t h = H[7];

  /* Data buffer, used as cyclic buffer.

     See FIPS PUB 180-4 paragraphs 5.2.1, 6.2. */

  uint32_t W[16];

#ifndef mhd_GET_32BIT_BE_UNALIGNED

  if (0 != (((uintptr_t) data) % mhd_UINT32_ALIGN))

  {

    /* Copy the unaligned input data to the aligned buffer */

    memcpy (W, data, mhd_SHA256_BLOCK_SIZE);

    /* The W[] buffer itself will be used as the source of the data,

     * but data will be reloaded in correct bytes order during

     * the next steps */

    data = (const void *) W;

  }

#endif /* mhd_GET_32BIT_BE_UNALIGNED */

  /* 'Ch' and 'Maj' macro functions are defined with

     widely-used optimization.

     See FIPS PUB 180-4 formulae 4.2, 4.3. */

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

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

  /* Unoptimized (original) versions: */

/* #define Ch(x,y,z)  ( ( (x) & (y) ) ^ ( ~(x) & (z) ) )          */

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

  /* Four 'Sigma' macro functions.

     See FIPS PUB 180-4 formulae 4.4, 4.5, 4.6, 4.7. */

#define SIG0(x)  (mhd_ROTR32 ((x), 2) ^ mhd_ROTR32 ((x), 13) ^ \

                  mhd_ROTR32 ((x), 22) )

#define SIG1(x)  (mhd_ROTR32 ((x), 6) ^ mhd_ROTR32 ((x), 11) ^ \

                  mhd_ROTR32 ((x), 25) )

#define sig0(x)  (mhd_ROTR32 ((x), 7) ^ mhd_ROTR32 ((x), 18) ^ \

                  ((x) >> 3) )

#define sig1(x)  (mhd_ROTR32 ((x), 17) ^ mhd_ROTR32 ((x),19) ^ \

                  ((x) >> 10) )

  /* One step of SHA-256 computation,

     see FIPS PUB 180-4 paragraph 6.2.2 step 3.

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

   * Note: first (vH += SIG1(vE) + Ch(vE,vF,vG) + kt + wt) equals T1 in FIPS PUB 180-4 paragraph 6.2.2 step 3.

           second (vH += SIG0(vA) + Maj(vE,vF,vC) equals T1 + T2 in FIPS PUB 180-4 paragraph 6.2.2 step 3.

   * Note: 'wt' must be used exactly one time in this macro as it change other data as well

           every time when used. */

#define SHA2STEP32(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)

  /* Get value of W(t) from input data buffer,

     See FIPS PUB 180-4 paragraph 6.2.

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

     see FIPS PUB 180-4 paragraph 3.1.2. */

  /* Use cast to (const void*) to mute compiler alignment warning,

   * data was already aligned in previous step */

#define GET_W_FROM_DATA(buf,t) \

        mhd_GET_32BIT_BE ((const void*) (((const uint8_t*) (buf)) + \

                                         (t) * mhd_SHA256_BYTES_IN_WORD))

  /* 'W' generation and assignment for 16 <= t <= 63.

     See FIPS PUB 180-4 paragraph 6.2.2.

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

     use 16 elements array of W as cyclic buffer.

   * Note: ((t-16)&0xf) have same value as (t&0xf) */

#define Wgen(w,t) ( (w)[(t - 16) & 0xf] + sig1 ((w)[((t) - 2) & 0xf])   \

                    + (w)[((t) - 7) & 0xf] + sig0 ((w)[((t) - 15) & 0xf]) )

#ifndef MHD_FAVOR_SMALL_CODE

  /* Note: instead of using K constants as array, all K values are specified

           individually for each step, see FIPS PUB 180-4 paragraph 4.2.2 for

           K values. */

  /* Note: instead of reassigning all working variables on each step,

           variables are rotated for each step:

             SHA2STEP32(a, b, c, d, e, f, g, h, K[0], data[0]);

             SHA2STEP32(h, a, b, c, d, e, f, g, K[1], data[1]);

           so current 'vD' will be used as 'vE' on next step,

           current 'vH' will be used as 'vA' on next step. */

#if mhd_BYTE_ORDER == mhd_BIG_ENDIAN

  if ((const void *) W == data)

  {

    /* The input data is already in the cyclic data buffer W[] in correct bytes

       order. */

    SHA2STEP32 (a, b, c, d, e, f, g, h, UINT32_C (0x428a2f98), W[0]);

    SHA2STEP32 (h, a, b, c, d, e, f, g, UINT32_C (0x71374491), W[1]);

    SHA2STEP32 (g, h, a, b, c, d, e, f, UINT32_C (0xb5c0fbcf), W[2]);

    SHA2STEP32 (f, g, h, a, b, c, d, e, UINT32_C (0xe9b5dba5), W[3]);

    SHA2STEP32 (e, f, g, h, a, b, c, d, UINT32_C (0x3956c25b), W[4]);

    SHA2STEP32 (d, e, f, g, h, a, b, c, UINT32_C (0x59f111f1), W[5]);

    SHA2STEP32 (c, d, e, f, g, h, a, b, UINT32_C (0x923f82a4), W[6]);

    SHA2STEP32 (b, c, d, e, f, g, h, a, UINT32_C (0xab1c5ed5), W[7]);

    SHA2STEP32 (a, b, c, d, e, f, g, h, UINT32_C (0xd807aa98), W[8]);

    SHA2STEP32 (h, a, b, c, d, e, f, g, UINT32_C (0x12835b01), W[9]);

    SHA2STEP32 (g, h, a, b, c, d, e, f, UINT32_C (0x243185be), W[10]);

    SHA2STEP32 (f, g, h, a, b, c, d, e, UINT32_C (0x550c7dc3), W[11]);

    SHA2STEP32 (e, f, g, h, a, b, c, d, UINT32_C (0x72be5d74), W[12]);

    SHA2STEP32 (d, e, f, g, h, a, b, c, UINT32_C (0x80deb1fe), W[13]);

    SHA2STEP32 (c, d, e, f, g, h, a, b, UINT32_C (0x9bdc06a7), W[14]);

    SHA2STEP32 (b, c, d, e, f, g, h, a, UINT32_C (0xc19bf174), W[15]);

  }

  else /* Combined with the next 'if' */

#endif /* mhd_BYTE_ORDER == mhd_BIG_ENDIAN */

  if (1)

  {

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

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

       stored in array of W elements. */

    SHA2STEP32 (a, b, c, d, e, f, g, h, UINT32_C (0x428a2f98), W[0] = \

                  GET_W_FROM_DATA (data, 0));

    SHA2STEP32 (h, a, b, c, d, e, f, g, UINT32_C (0x71374491), W[1] = \

                  GET_W_FROM_DATA (data, 1));

    SHA2STEP32 (g, h, a, b, c, d, e, f, UINT32_C (0xb5c0fbcf), W[2] = \

                  GET_W_FROM_DATA (data, 2));

    SHA2STEP32 (f, g, h, a, b, c, d, e, UINT32_C (0xe9b5dba5), W[3] = \

                  GET_W_FROM_DATA (data, 3));

    SHA2STEP32 (e, f, g, h, a, b, c, d, UINT32_C (0x3956c25b), W[4] = \

                  GET_W_FROM_DATA (data, 4));

    SHA2STEP32 (d, e, f, g, h, a, b, c, UINT32_C (0x59f111f1), W[5] = \

                  GET_W_FROM_DATA (data, 5));

    SHA2STEP32 (c, d, e, f, g, h, a, b, UINT32_C (0x923f82a4), W[6] = \

                  GET_W_FROM_DATA (data, 6));

    SHA2STEP32 (b, c, d, e, f, g, h, a, UINT32_C (0xab1c5ed5), W[7] = \

                  GET_W_FROM_DATA (data, 7));

    SHA2STEP32 (a, b, c, d, e, f, g, h, UINT32_C (0xd807aa98), W[8] = \

                  GET_W_FROM_DATA (data, 8));

    SHA2STEP32 (h, a, b, c, d, e, f, g, UINT32_C (0x12835b01), W[9] = \

                  GET_W_FROM_DATA (data, 9));

    SHA2STEP32 (g, h, a, b, c, d, e, f, UINT32_C (0x243185be), W[10] = \

                  GET_W_FROM_DATA (data, 10));

    SHA2STEP32 (f, g, h, a, b, c, d, e, UINT32_C (0x550c7dc3), W[11] = \

                  GET_W_FROM_DATA (data, 11));

    SHA2STEP32 (e, f, g, h, a, b, c, d, UINT32_C (0x72be5d74), W[12] = \

                  GET_W_FROM_DATA (data, 12));

    SHA2STEP32 (d, e, f, g, h, a, b, c, UINT32_C (0x80deb1fe), W[13] = \

                  GET_W_FROM_DATA (data, 13));

    SHA2STEP32 (c, d, e, f, g, h, a, b, UINT32_C (0x9bdc06a7), W[14] = \

                  GET_W_FROM_DATA (data, 14));

    SHA2STEP32 (b, c, d, e, f, g, h, a, UINT32_C (0xc19bf174), W[15] = \

                  GET_W_FROM_DATA (data, 15));

  }

  /* During last 48 steps, before making any calculations 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. */

  /* Note: instead of using K constants as array, all K values are specified

     individually for each step, see FIPS PUB 180-4 paragraph 4.2.2 for K values. */

  SHA2STEP32 (a, b, c, d, e, f, g, h, UINT32_C (0xe49b69c1), W[16 & 0xf] = \

                Wgen (W,16));

  SHA2STEP32 (h, a, b, c, d, e, f, g, UINT32_C (0xefbe4786), W[17 & 0xf] = \

                Wgen (W,17));

  SHA2STEP32 (g, h, a, b, c, d, e, f, UINT32_C (0x0fc19dc6), W[18 & 0xf] = \

                Wgen (W,18));

  SHA2STEP32 (f, g, h, a, b, c, d, e, UINT32_C (0x240ca1cc), W[19 & 0xf] = \

                Wgen (W,19));

  SHA2STEP32 (e, f, g, h, a, b, c, d, UINT32_C (0x2de92c6f), W[20 & 0xf] = \

                Wgen (W,20));

  SHA2STEP32 (d, e, f, g, h, a, b, c, UINT32_C (0x4a7484aa), W[21 & 0xf] = \

                Wgen (W,21));

  SHA2STEP32 (c, d, e, f, g, h, a, b, UINT32_C (0x5cb0a9dc), W[22 & 0xf] = \

                Wgen (W,22));

  SHA2STEP32 (b, c, d, e, f, g, h, a, UINT32_C (0x76f988da), W[23 & 0xf] = \

                Wgen (W,23));

  SHA2STEP32 (a, b, c, d, e, f, g, h, UINT32_C (0x983e5152), W[24 & 0xf] = \

                Wgen (W,24));

  SHA2STEP32 (h, a, b, c, d, e, f, g, UINT32_C (0xa831c66d), W[25 & 0xf] = \

                Wgen (W,25));

  SHA2STEP32 (g, h, a, b, c, d, e, f, UINT32_C (0xb00327c8), W[26 & 0xf] = \

                Wgen (W,26));

  SHA2STEP32 (f, g, h, a, b, c, d, e, UINT32_C (0xbf597fc7), W[27 & 0xf] = \

                Wgen (W,27));

  SHA2STEP32 (e, f, g, h, a, b, c, d, UINT32_C (0xc6e00bf3), W[28 & 0xf] = \

                Wgen (W,28));

  SHA2STEP32 (d, e, f, g, h, a, b, c, UINT32_C (0xd5a79147), W[29 & 0xf] = \

                Wgen (W,29));

  SHA2STEP32 (c, d, e, f, g, h, a, b, UINT32_C (0x06ca6351), W[30 & 0xf] = \

                Wgen (W,30));

  SHA2STEP32 (b, c, d, e, f, g, h, a, UINT32_C (0x14292967), W[31 & 0xf] = \

                Wgen (W,31));

  SHA2STEP32 (a, b, c, d, e, f, g, h, UINT32_C (0x27b70a85), W[32 & 0xf] = \

                Wgen (W,32));

  SHA2STEP32 (h, a, b, c, d, e, f, g, UINT32_C (0x2e1b2138), W[33 & 0xf] = \

                Wgen (W,33));

  SHA2STEP32 (g, h, a, b, c, d, e, f, UINT32_C (0x4d2c6dfc), W[34 & 0xf] = \

                Wgen (W,34));

  SHA2STEP32 (f, g, h, a, b, c, d, e, UINT32_C (0x53380d13), W[35 & 0xf] = \

                Wgen (W,35));

  SHA2STEP32 (e, f, g, h, a, b, c, d, UINT32_C (0x650a7354), W[36 & 0xf] = \

                Wgen (W,36));

  SHA2STEP32 (d, e, f, g, h, a, b, c, UINT32_C (0x766a0abb), W[37 & 0xf] = \

                Wgen (W,37));

  SHA2STEP32 (c, d, e, f, g, h, a, b, UINT32_C (0x81c2c92e), W[38 & 0xf] = \

                Wgen (W,38));

  SHA2STEP32 (b, c, d, e, f, g, h, a, UINT32_C (0x92722c85), W[39 & 0xf] = \

                Wgen (W,39));

  SHA2STEP32 (a, b, c, d, e, f, g, h, UINT32_C (0xa2bfe8a1), W[40 & 0xf] = \

                Wgen (W,40));

  SHA2STEP32 (h, a, b, c, d, e, f, g, UINT32_C (0xa81a664b), W[41 & 0xf] = \

                Wgen (W,41));

  SHA2STEP32 (g, h, a, b, c, d, e, f, UINT32_C (0xc24b8b70), W[42 & 0xf] = \

                Wgen (W,42));

  SHA2STEP32 (f, g, h, a, b, c, d, e, UINT32_C (0xc76c51a3), W[43 & 0xf] = \

                Wgen (W,43));

  SHA2STEP32 (e, f, g, h, a, b, c, d, UINT32_C (0xd192e819), W[44 & 0xf] = \

                Wgen (W,44));

  SHA2STEP32 (d, e, f, g, h, a, b, c, UINT32_C (0xd6990624), W[45 & 0xf] = \

                Wgen (W,45));

  SHA2STEP32 (c, d, e, f, g, h, a, b, UINT32_C (0xf40e3585), W[46 & 0xf] = \

                Wgen (W,46));

  SHA2STEP32 (b, c, d, e, f, g, h, a, UINT32_C (0x106aa070), W[47 & 0xf] = \

                Wgen (W,47));

  SHA2STEP32 (a, b, c, d, e, f, g, h, UINT32_C (0x19a4c116), W[48 & 0xf] = \

                Wgen (W,48));

  SHA2STEP32 (h, a, b, c, d, e, f, g, UINT32_C (0x1e376c08), W[49 & 0xf] = \

                Wgen (W,49));

  SHA2STEP32 (g, h, a, b, c, d, e, f, UINT32_C (0x2748774c), W[50 & 0xf] = \

                Wgen (W,50));

  SHA2STEP32 (f, g, h, a, b, c, d, e, UINT32_C (0x34b0bcb5), W[51 & 0xf] = \

                Wgen (W,51));

  SHA2STEP32 (e, f, g, h, a, b, c, d, UINT32_C (0x391c0cb3), W[52 & 0xf] = \

                Wgen (W,52));

  SHA2STEP32 (d, e, f, g, h, a, b, c, UINT32_C (0x4ed8aa4a), W[53 & 0xf] = \

                Wgen (W,53));

  SHA2STEP32 (c, d, e, f, g, h, a, b, UINT32_C (0x5b9cca4f), W[54 & 0xf] = \

                Wgen (W,54));

  SHA2STEP32 (b, c, d, e, f, g, h, a, UINT32_C (0x682e6ff3), W[55 & 0xf] = \

                Wgen (W,55));

  SHA2STEP32 (a, b, c, d, e, f, g, h, UINT32_C (0x748f82ee), W[56 & 0xf] = \

                Wgen (W,56));

  SHA2STEP32 (h, a, b, c, d, e, f, g, UINT32_C (0x78a5636f), W[57 & 0xf] = \

                Wgen (W,57));

  SHA2STEP32 (g, h, a, b, c, d, e, f, UINT32_C (0x84c87814), W[58 & 0xf] = \

                Wgen (W,58));

  SHA2STEP32 (f, g, h, a, b, c, d, e, UINT32_C (0x8cc70208), W[59 & 0xf] = \

                Wgen (W,59));

  SHA2STEP32 (e, f, g, h, a, b, c, d, UINT32_C (0x90befffa), W[60 & 0xf] = \

                Wgen (W,60));

  SHA2STEP32 (d, e, f, g, h, a, b, c, UINT32_C (0xa4506ceb), W[61 & 0xf] = \

                Wgen (W,61));

  SHA2STEP32 (c, d, e, f, g, h, a, b, UINT32_C (0xbef9a3f7), W[62 & 0xf] = \

                Wgen (W,62));

  SHA2STEP32 (b, c, d, e, f, g, h, a, UINT32_C (0xc67178f2), W[63 & 0xf] = \

                Wgen (W,63));

#else  /* ! MHD_FAVOR_SMALL_CODE */

  if (1)

  {

    unsigned int t;

    /* K constants array.

       See FIPS PUB 180-4 paragraph 4.2.2 for K values. */

    static const uint32_t K[80] =

    { UINT32_C (0x428a2f98),  UINT32_C (0x71374491),  UINT32_C (0xb5c0fbcf),

      UINT32_C (0xe9b5dba5),  UINT32_C (0x3956c25b),  UINT32_C (0x59f111f1),

      UINT32_C (0x923f82a4),  UINT32_C (0xab1c5ed5),  UINT32_C (0xd807aa98),

      UINT32_C (0x12835b01),  UINT32_C (0x243185be),  UINT32_C (0x550c7dc3),

      UINT32_C (0x72be5d74),  UINT32_C (0x80deb1fe),  UINT32_C (0x9bdc06a7),

      UINT32_C (0xc19bf174),  UINT32_C (0xe49b69c1),  UINT32_C (0xefbe4786),

      UINT32_C (0x0fc19dc6),  UINT32_C (0x240ca1cc),  UINT32_C (0x2de92c6f),

      UINT32_C (0x4a7484aa),  UINT32_C (0x5cb0a9dc),  UINT32_C (0x76f988da),

      UINT32_C (0x983e5152),  UINT32_C (0xa831c66d),  UINT32_C (0xb00327c8),

      UINT32_C (0xbf597fc7),  UINT32_C (0xc6e00bf3),  UINT32_C (0xd5a79147),

      UINT32_C (0x06ca6351),  UINT32_C (0x14292967),  UINT32_C (0x27b70a85),

      UINT32_C (0x2e1b2138),  UINT32_C (0x4d2c6dfc),  UINT32_C (0x53380d13),

      UINT32_C (0x650a7354),  UINT32_C (0x766a0abb),  UINT32_C (0x81c2c92e),

      UINT32_C (0x92722c85),  UINT32_C (0xa2bfe8a1),  UINT32_C (0xa81a664b),

      UINT32_C (0xc24b8b70),  UINT32_C (0xc76c51a3),  UINT32_C (0xd192e819),

      UINT32_C (0xd6990624),  UINT32_C (0xf40e3585),  UINT32_C (0x106aa070),

      UINT32_C (0x19a4c116),  UINT32_C (0x1e376c08),  UINT32_C (0x2748774c),

      UINT32_C (0x34b0bcb5),  UINT32_C (0x391c0cb3),  UINT32_C (0x4ed8aa4a),

      UINT32_C (0x5b9cca4f),  UINT32_C (0x682e6ff3),  UINT32_C (0x748f82ee),

      UINT32_C (0x78a5636f),  UINT32_C (0x84c87814),  UINT32_C (0x8cc70208),

      UINT32_C (0x90befffa),  UINT32_C (0xa4506ceb),  UINT32_C (0xbef9a3f7),

      UINT32_C (0xc67178f2) };

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

       see FIPS PUB 180-4 paragraph 6.2.2 step 3.

     * Note: this version of macro reassign all working variable on

             each step. */

#define SHA2STEP32RV(vA,vB,vC,vD,vE,vF,vG,vH,kt,wt) do {              \

          uint32_t tmp_h_ = (vH);                                           \

          SHA2STEP32 ((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)

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

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

       stored in array of W elements. */

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

    {

      SHA2STEP32RV (a, b, c, d, e, f, g, h, K[t], \

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

    }

    /* During last 48 steps, before making any calculations 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 < 64; ++t)

    {

      SHA2STEP32RV (a, b, c, d, e, f, g, h, K[t], W[t & 15] = Wgen (W,t));

    }

  }

#endif /* ! MHD_FAVOR_SMALL_CODE */

  /* Compute intermediate hash.

     See FIPS PUB 180-4 paragraph 6.2.2 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;

}

MHD_INTERNAL MHD_FN_PAR_NONNULL_ALL_

MHD_FN_PAR_IN_SIZE_ (3, 2) void

mhd_SHA256_update (struct mhd_Sha256CtxInt *restrict ctx,

                   size_t size,

                   const uint8_t *restrict data)

{

  unsigned bytes_have; /**< Number of bytes in buffer */

  mhd_assert (0 != size);

  /* Note: (count & (mhd_SHA256_BLOCK_SIZE-1))

           equals (count % mhd_SHA256_BLOCK_SIZE) for this block size. */

  bytes_have = (unsigned) (ctx->count & (mhd_SHA256_BLOCK_SIZE - 1));

  ctx->count += size;

  if (0 != bytes_have)

  {

    unsigned bytes_left = mhd_SHA256_BLOCK_SIZE - bytes_have;

    if (size >= bytes_left)

    {     /* Combine new data with data in the buffer and

             process full block. */

      memcpy (((uint8_t *) ctx->buffer) + bytes_have,

              data,

              bytes_left);

      data += bytes_left;

      size -= bytes_left;

      sha256_transform (ctx->H, ctx->buffer);

      bytes_have = 0;

    }

  }

  while (mhd_SHA256_BLOCK_SIZE <= size)

  {   /* Process any full blocks of new data directly,

         without copying to the buffer. */

    sha256_transform (ctx->H, data);

    data += mhd_SHA256_BLOCK_SIZE;

    size -= mhd_SHA256_BLOCK_SIZE;

  }

  if (0 != size)

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

         to the buffer. */

    memcpy (((uint8_t *) ctx->buffer) + bytes_have, data, size);

  }

}

/**

 * Size of "length" padding addition in bytes.

 * See FIPS PUB 180-4 paragraph 5.1.1.

 */

#define SHA256_SIZE_OF_LEN_ADD (64 / 8)

MHD_INTERNAL MHD_FN_PAR_NONNULL_ALL_ void

mhd_SHA256_finish (struct mhd_Sha256CtxInt *restrict ctx,

                   uint8_t digest[mhd_SHA256_DIGEST_SIZE])

{

  uint64_t num_bits;   /**< Number of processed bits */

  unsigned bytes_have; /**< Number of bytes in buffer */

  num_bits = ctx->count << 3;

  /* Note: (count & (mhd_SHA256_BLOCK_SIZE-1))

           equal (count % mhd_SHA256_BLOCK_SIZE) for this block size. */

  bytes_have = (unsigned) (ctx->count & (mhd_SHA256_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 paragraph 5.1.1. */

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

     therefore position of first padding bit in byte is always

     predefined (0x80). */

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

     processed immediately). */

  ((uint8_t *) ctx->buffer)[bytes_have++] = 0x80;

  if (mhd_SHA256_BLOCK_SIZE - bytes_have < SHA256_SIZE_OF_LEN_ADD)

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

         Pad current block with zeros and process it. */

    if (bytes_have < mhd_SHA256_BLOCK_SIZE)

      memset (((uint8_t *) ctx->buffer) + bytes_have, 0,

              mhd_SHA256_BLOCK_SIZE - bytes_have);

    /* Process full block. */

    sha256_transform (ctx->H, ctx->buffer);

    /* Start new block. */

    bytes_have = 0;

  }

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

  memset (((uint8_t *) ctx->buffer) + bytes_have, 0,

          mhd_SHA256_BLOCK_SIZE - SHA256_SIZE_OF_LEN_ADD - bytes_have);

  /* Put the number of bits in processed message as big-endian value. */

  mhd_PUT_64BIT_BE_UNALIGN (ctx->buffer + mhd_SHA256_BLOCK_SIZE_WORDS - 2,

                            num_bits);

  /* Process full final block. */

  sha256_transform (ctx->H, ctx->buffer);

  /* Put final hash/digest in BE mode */

  if (1)

  {

    bool use_tmp_buf_to_align_result;

#if defined(mhd_PUT_32BIT_BE_UNALIGNED)

    use_tmp_buf_to_align_result = false;

#elif defined (MHD_FAVOR_SMALL_CODE)

    use_tmp_buf_to_align_result = true; /* smaller code: eliminated branch below */

#else

    use_tmp_buf_to_align_result =

      (0 != ((uintptr_t) digest) % mhd_UINT32_ALIGN);

#endif

    if (use_tmp_buf_to_align_result)

    {

      /* If storing of the final result requires aligned address and

         the destination address is not aligned or compact code is used,

         store the final digest in aligned temporary buffer first, then

         copy it to the destination. */

      uint32_t alig_dgst[mhd_SHA256_DIGEST_SIZE_WORDS];

      mhd_PUT_32BIT_BE (alig_dgst + 0, ctx->H[0]);

      mhd_PUT_32BIT_BE (alig_dgst + 1, ctx->H[1]);

      mhd_PUT_32BIT_BE (alig_dgst + 2, ctx->H[2]);

      mhd_PUT_32BIT_BE (alig_dgst + 3, ctx->H[3]);

      mhd_PUT_32BIT_BE (alig_dgst + 4, ctx->H[4]);

      mhd_PUT_32BIT_BE (alig_dgst + 5, ctx->H[5]);

      mhd_PUT_32BIT_BE (alig_dgst + 6, ctx->H[6]);

      mhd_PUT_32BIT_BE (alig_dgst + 7, ctx->H[7]);

      /* Copy result to unaligned destination address */

      memcpy (digest, alig_dgst, mhd_SHA256_DIGEST_SIZE);

    }

    else

    {

      /* Use cast to (void*) here to mute compiler alignment warnings.

       * Compilers are not smart enough to see that alignment has been checked. */

      mhd_PUT_32BIT_BE ((void *) (digest + 0 * mhd_SHA256_BYTES_IN_WORD), \

                        ctx->H[0]);

      mhd_PUT_32BIT_BE ((void *) (digest + 1 * mhd_SHA256_BYTES_IN_WORD), \

                        ctx->H[1]);

      mhd_PUT_32BIT_BE ((void *) (digest + 2 * mhd_SHA256_BYTES_IN_WORD), \

                        ctx->H[2]);

      mhd_PUT_32BIT_BE ((void *) (digest + 3 * mhd_SHA256_BYTES_IN_WORD), \

                        ctx->H[3]);

      mhd_PUT_32BIT_BE ((void *) (digest + 4 * mhd_SHA256_BYTES_IN_WORD), \

                        ctx->H[4]);

      mhd_PUT_32BIT_BE ((void *) (digest + 5 * mhd_SHA256_BYTES_IN_WORD), \

                        ctx->H[5]);

      mhd_PUT_32BIT_BE ((void *) (digest + 6 * mhd_SHA256_BYTES_IN_WORD), \

                        ctx->H[6]);

      mhd_PUT_32BIT_BE ((void *) (digest + 7 * mhd_SHA256_BYTES_IN_WORD), \

                        ctx->H[7]);

    }

  }

  /* Erase potentially sensitive data. */

  memset (ctx, 0, sizeof(struct mhd_Sha256CtxInt));

}

mhd_DATA_TRUNCATION_RUNTIME_CHECK_RESTORE