libmicrohttpd2

HTTP server C library (MHD 2.x, alpha)
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sha256_int.c (25632B)


      1 /* SPDX-License-Identifier: LGPL-2.1-or-later OR (GPL-2.0-or-later WITH eCos-exception-2.0) */
      2 /*
      3   This file is part of GNU libmicrohttpd.
      4   Copyright (C) 2019-2024 Evgeny Grin (Karlson2k)
      5 
      6   GNU libmicrohttpd is free software; you can redistribute it and/or
      7   modify it under the terms of the GNU Lesser General Public
      8   License as published by the Free Software Foundation; either
      9   version 2.1 of the License, or (at your option) any later version.
     10 
     11   GNU libmicrohttpd is distributed in the hope that it will be useful,
     12   but WITHOUT ANY WARRANTY; without even the implied warranty of
     13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     14   Lesser General Public License for more details.
     15 
     16   Alternatively, you can redistribute GNU libmicrohttpd and/or
     17   modify it under the terms of the GNU General Public License as
     18   published by the Free Software Foundation; either version 2 of
     19   the License, or (at your option) any later version, together
     20   with the eCos exception, as follows:
     21 
     22     As a special exception, if other files instantiate templates or
     23     use macros or inline functions from this file, or you compile this
     24     file and link it with other works to produce a work based on this
     25     file, this file does not by itself cause the resulting work to be
     26     covered by the GNU General Public License. However the source code
     27     for this file must still be made available in accordance with
     28     section (3) of the GNU General Public License v2.
     29 
     30     This exception does not invalidate any other reasons why a work
     31     based on this file might be covered by the GNU General Public
     32     License.
     33 
     34   You should have received copies of the GNU Lesser General Public
     35   License and the GNU General Public License along with this library;
     36   if not, see <https://www.gnu.org/licenses/>.
     37 */
     38 
     39 /**
     40  * @file src/mhd2/sha256.c
     41  * @brief  Calculation of SHA-256 digest as defined in FIPS PUB 180-4 (2015)
     42  * @author Karlson2k (Evgeny Grin)
     43  */
     44 
     45 #include "mhd_sys_options.h"
     46 
     47 #include "sys_bool_type.h"
     48 
     49 #include <string.h>
     50 #include "mhd_bithelpers.h"
     51 #include "mhd_align.h"
     52 #include "mhd_assert.h"
     53 
     54 #include "sha256_int.h"
     55 
     56 MHD_INTERNAL void MHD_FN_PAR_NONNULL_ALL_
     57 mhd_SHA256_init (struct mhd_Sha256CtxInt *ctx)
     58 {
     59   /* Initial hash values, see FIPS PUB 180-4 paragraph 5.3.3 */
     60   /* First thirty-two bits of the fractional parts of the square
     61    * roots of the first eight prime numbers: 2, 3, 5, 7, 11, 13,
     62    * 17, 19." */
     63   ctx->H[0] = UINT32_C (0x6a09e667);
     64   ctx->H[1] = UINT32_C (0xbb67ae85);
     65   ctx->H[2] = UINT32_C (0x3c6ef372);
     66   ctx->H[3] = UINT32_C (0xa54ff53a);
     67   ctx->H[4] = UINT32_C (0x510e527f);
     68   ctx->H[5] = UINT32_C (0x9b05688c);
     69   ctx->H[6] = UINT32_C (0x1f83d9ab);
     70   ctx->H[7] = UINT32_C (0x5be0cd19);
     71 
     72   /* Initialise number of bytes. */
     73   ctx->count = 0;
     74 }
     75 
     76 
     77 mhd_DATA_TRUNCATION_RUNTIME_CHECK_DISABLE
     78 
     79 static MHD_FN_PAR_NONNULL_ALL_ void
     80 sha256_transform (uint32_t H[mhd_SHA256_DIGEST_SIZE_WORDS],
     81                   const void *restrict data)
     82 {
     83   /* Working variables,
     84      see FIPS PUB 180-4 paragraph 6.2. */
     85   uint32_t a = H[0];
     86   uint32_t b = H[1];
     87   uint32_t c = H[2];
     88   uint32_t d = H[3];
     89   uint32_t e = H[4];
     90   uint32_t f = H[5];
     91   uint32_t g = H[6];
     92   uint32_t h = H[7];
     93 
     94   /* Data buffer, used as cyclic buffer.
     95      See FIPS PUB 180-4 paragraphs 5.2.1, 6.2. */
     96   uint32_t W[16];
     97 
     98 #ifndef mhd_GET_32BIT_BE_UNALIGNED
     99   if (0 != (((uintptr_t) data) % mhd_UINT32_ALIGN))
    100   {
    101     /* Copy the unaligned input data to the aligned buffer */
    102     memcpy (W, data, mhd_SHA256_BLOCK_SIZE);
    103     /* The W[] buffer itself will be used as the source of the data,
    104      * but data will be reloaded in correct bytes order during
    105      * the next steps */
    106     data = (const void *) W;
    107   }
    108 #endif /* mhd_GET_32BIT_BE_UNALIGNED */
    109 
    110   /* 'Ch' and 'Maj' macro functions are defined with
    111      widely-used optimization.
    112      See FIPS PUB 180-4 formulae 4.2, 4.3. */
    113 #define Ch(x,y,z)     ( (z) ^ ((x) & ((y) ^ (z))) )
    114 #define Maj(x,y,z)    ( ((x) & (y)) ^ ((z) & ((x) ^ (y))) )
    115   /* Unoptimized (original) versions: */
    116 /* #define Ch(x,y,z)  ( ( (x) & (y) ) ^ ( ~(x) & (z) ) )          */
    117 /* #define Maj(x,y,z) ( ((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z)) ) */
    118 
    119   /* Four 'Sigma' macro functions.
    120      See FIPS PUB 180-4 formulae 4.4, 4.5, 4.6, 4.7. */
    121 #define SIG0(x)  (mhd_ROTR32 ((x), 2) ^ mhd_ROTR32 ((x), 13) ^ \
    122                   mhd_ROTR32 ((x), 22) )
    123 #define SIG1(x)  (mhd_ROTR32 ((x), 6) ^ mhd_ROTR32 ((x), 11) ^ \
    124                   mhd_ROTR32 ((x), 25) )
    125 #define sig0(x)  (mhd_ROTR32 ((x), 7) ^ mhd_ROTR32 ((x), 18) ^ \
    126                   ((x) >> 3) )
    127 #define sig1(x)  (mhd_ROTR32 ((x), 17) ^ mhd_ROTR32 ((x),19) ^ \
    128                   ((x) >> 10) )
    129 
    130   /* One step of SHA-256 computation,
    131      see FIPS PUB 180-4 paragraph 6.2.2 step 3.
    132    * Note: this macro updates working variables in-place, without rotation.
    133    * Note: first (vH += SIG1(vE) + Ch(vE,vF,vG) + kt + wt) equals T1 in FIPS PUB 180-4 paragraph 6.2.2 step 3.
    134            second (vH += SIG0(vA) + Maj(vE,vF,vC) equals T1 + T2 in FIPS PUB 180-4 paragraph 6.2.2 step 3.
    135    * Note: 'wt' must be used exactly one time in this macro as it change other data as well
    136            every time when used. */
    137 #define SHA2STEP32(vA,vB,vC,vD,vE,vF,vG,vH,kt,wt) do {                  \
    138           (vD) += ((vH) += SIG1 ((vE)) + Ch ((vE),(vF),(vG)) + (kt) + (wt));  \
    139           (vH) += SIG0 ((vA)) + Maj ((vA),(vB),(vC)); } while (0)
    140 
    141   /* Get value of W(t) from input data buffer,
    142      See FIPS PUB 180-4 paragraph 6.2.
    143      Input data must be read in big-endian bytes order,
    144      see FIPS PUB 180-4 paragraph 3.1.2. */
    145   /* Use cast to (const void*) to mute compiler alignment warning,
    146    * data was already aligned in previous step */
    147 #define GET_W_FROM_DATA(buf,t) \
    148         mhd_GET_32BIT_BE ((const void*) (((const uint8_t*) (buf)) + \
    149                                          (t) * mhd_SHA256_BYTES_IN_WORD))
    150 
    151   /* 'W' generation and assignment for 16 <= t <= 63.
    152      See FIPS PUB 180-4 paragraph 6.2.2.
    153      As only last 16 'W' are used in calculations, it is possible to
    154      use 16 elements array of W as cyclic buffer.
    155    * Note: ((t-16)&0xf) have same value as (t&0xf) */
    156 #define Wgen(w,t) ( (w)[(t - 16) & 0xf] + sig1 ((w)[((t) - 2) & 0xf])   \
    157                     + (w)[((t) - 7) & 0xf] + sig0 ((w)[((t) - 15) & 0xf]) )
    158 
    159 #ifndef MHD_FAVOR_SMALL_CODE
    160 
    161   /* Note: instead of using K constants as array, all K values are specified
    162            individually for each step, see FIPS PUB 180-4 paragraph 4.2.2 for
    163            K values. */
    164   /* Note: instead of reassigning all working variables on each step,
    165            variables are rotated for each step:
    166              SHA2STEP32(a, b, c, d, e, f, g, h, K[0], data[0]);
    167              SHA2STEP32(h, a, b, c, d, e, f, g, K[1], data[1]);
    168            so current 'vD' will be used as 'vE' on next step,
    169            current 'vH' will be used as 'vA' on next step. */
    170 #if mhd_BYTE_ORDER == mhd_BIG_ENDIAN
    171   if ((const void *) W == data)
    172   {
    173     /* The input data is already in the cyclic data buffer W[] in correct bytes
    174        order. */
    175     SHA2STEP32 (a, b, c, d, e, f, g, h, UINT32_C (0x428a2f98), W[0]);
    176     SHA2STEP32 (h, a, b, c, d, e, f, g, UINT32_C (0x71374491), W[1]);
    177     SHA2STEP32 (g, h, a, b, c, d, e, f, UINT32_C (0xb5c0fbcf), W[2]);
    178     SHA2STEP32 (f, g, h, a, b, c, d, e, UINT32_C (0xe9b5dba5), W[3]);
    179     SHA2STEP32 (e, f, g, h, a, b, c, d, UINT32_C (0x3956c25b), W[4]);
    180     SHA2STEP32 (d, e, f, g, h, a, b, c, UINT32_C (0x59f111f1), W[5]);
    181     SHA2STEP32 (c, d, e, f, g, h, a, b, UINT32_C (0x923f82a4), W[6]);
    182     SHA2STEP32 (b, c, d, e, f, g, h, a, UINT32_C (0xab1c5ed5), W[7]);
    183     SHA2STEP32 (a, b, c, d, e, f, g, h, UINT32_C (0xd807aa98), W[8]);
    184     SHA2STEP32 (h, a, b, c, d, e, f, g, UINT32_C (0x12835b01), W[9]);
    185     SHA2STEP32 (g, h, a, b, c, d, e, f, UINT32_C (0x243185be), W[10]);
    186     SHA2STEP32 (f, g, h, a, b, c, d, e, UINT32_C (0x550c7dc3), W[11]);
    187     SHA2STEP32 (e, f, g, h, a, b, c, d, UINT32_C (0x72be5d74), W[12]);
    188     SHA2STEP32 (d, e, f, g, h, a, b, c, UINT32_C (0x80deb1fe), W[13]);
    189     SHA2STEP32 (c, d, e, f, g, h, a, b, UINT32_C (0x9bdc06a7), W[14]);
    190     SHA2STEP32 (b, c, d, e, f, g, h, a, UINT32_C (0xc19bf174), W[15]);
    191   }
    192   else /* Combined with the next 'if' */
    193 #endif /* mhd_BYTE_ORDER == mhd_BIG_ENDIAN */
    194   if (1)
    195   {
    196     /* During first 16 steps, before making any calculations on each step,
    197        the W element is read from input data buffer as big-endian value and
    198        stored in array of W elements. */
    199     SHA2STEP32 (a, b, c, d, e, f, g, h, UINT32_C (0x428a2f98), W[0] = \
    200                   GET_W_FROM_DATA (data, 0));
    201     SHA2STEP32 (h, a, b, c, d, e, f, g, UINT32_C (0x71374491), W[1] = \
    202                   GET_W_FROM_DATA (data, 1));
    203     SHA2STEP32 (g, h, a, b, c, d, e, f, UINT32_C (0xb5c0fbcf), W[2] = \
    204                   GET_W_FROM_DATA (data, 2));
    205     SHA2STEP32 (f, g, h, a, b, c, d, e, UINT32_C (0xe9b5dba5), W[3] = \
    206                   GET_W_FROM_DATA (data, 3));
    207     SHA2STEP32 (e, f, g, h, a, b, c, d, UINT32_C (0x3956c25b), W[4] = \
    208                   GET_W_FROM_DATA (data, 4));
    209     SHA2STEP32 (d, e, f, g, h, a, b, c, UINT32_C (0x59f111f1), W[5] = \
    210                   GET_W_FROM_DATA (data, 5));
    211     SHA2STEP32 (c, d, e, f, g, h, a, b, UINT32_C (0x923f82a4), W[6] = \
    212                   GET_W_FROM_DATA (data, 6));
    213     SHA2STEP32 (b, c, d, e, f, g, h, a, UINT32_C (0xab1c5ed5), W[7] = \
    214                   GET_W_FROM_DATA (data, 7));
    215     SHA2STEP32 (a, b, c, d, e, f, g, h, UINT32_C (0xd807aa98), W[8] = \
    216                   GET_W_FROM_DATA (data, 8));
    217     SHA2STEP32 (h, a, b, c, d, e, f, g, UINT32_C (0x12835b01), W[9] = \
    218                   GET_W_FROM_DATA (data, 9));
    219     SHA2STEP32 (g, h, a, b, c, d, e, f, UINT32_C (0x243185be), W[10] = \
    220                   GET_W_FROM_DATA (data, 10));
    221     SHA2STEP32 (f, g, h, a, b, c, d, e, UINT32_C (0x550c7dc3), W[11] = \
    222                   GET_W_FROM_DATA (data, 11));
    223     SHA2STEP32 (e, f, g, h, a, b, c, d, UINT32_C (0x72be5d74), W[12] = \
    224                   GET_W_FROM_DATA (data, 12));
    225     SHA2STEP32 (d, e, f, g, h, a, b, c, UINT32_C (0x80deb1fe), W[13] = \
    226                   GET_W_FROM_DATA (data, 13));
    227     SHA2STEP32 (c, d, e, f, g, h, a, b, UINT32_C (0x9bdc06a7), W[14] = \
    228                   GET_W_FROM_DATA (data, 14));
    229     SHA2STEP32 (b, c, d, e, f, g, h, a, UINT32_C (0xc19bf174), W[15] = \
    230                   GET_W_FROM_DATA (data, 15));
    231   }
    232 
    233   /* During last 48 steps, before making any calculations on each step,
    234      current W element is generated from other W elements of the cyclic buffer
    235      and the generated value is stored back in the cyclic buffer. */
    236   /* Note: instead of using K constants as array, all K values are specified
    237      individually for each step, see FIPS PUB 180-4 paragraph 4.2.2 for K values. */
    238   SHA2STEP32 (a, b, c, d, e, f, g, h, UINT32_C (0xe49b69c1), W[16 & 0xf] = \
    239                 Wgen (W,16));
    240   SHA2STEP32 (h, a, b, c, d, e, f, g, UINT32_C (0xefbe4786), W[17 & 0xf] = \
    241                 Wgen (W,17));
    242   SHA2STEP32 (g, h, a, b, c, d, e, f, UINT32_C (0x0fc19dc6), W[18 & 0xf] = \
    243                 Wgen (W,18));
    244   SHA2STEP32 (f, g, h, a, b, c, d, e, UINT32_C (0x240ca1cc), W[19 & 0xf] = \
    245                 Wgen (W,19));
    246   SHA2STEP32 (e, f, g, h, a, b, c, d, UINT32_C (0x2de92c6f), W[20 & 0xf] = \
    247                 Wgen (W,20));
    248   SHA2STEP32 (d, e, f, g, h, a, b, c, UINT32_C (0x4a7484aa), W[21 & 0xf] = \
    249                 Wgen (W,21));
    250   SHA2STEP32 (c, d, e, f, g, h, a, b, UINT32_C (0x5cb0a9dc), W[22 & 0xf] = \
    251                 Wgen (W,22));
    252   SHA2STEP32 (b, c, d, e, f, g, h, a, UINT32_C (0x76f988da), W[23 & 0xf] = \
    253                 Wgen (W,23));
    254   SHA2STEP32 (a, b, c, d, e, f, g, h, UINT32_C (0x983e5152), W[24 & 0xf] = \
    255                 Wgen (W,24));
    256   SHA2STEP32 (h, a, b, c, d, e, f, g, UINT32_C (0xa831c66d), W[25 & 0xf] = \
    257                 Wgen (W,25));
    258   SHA2STEP32 (g, h, a, b, c, d, e, f, UINT32_C (0xb00327c8), W[26 & 0xf] = \
    259                 Wgen (W,26));
    260   SHA2STEP32 (f, g, h, a, b, c, d, e, UINT32_C (0xbf597fc7), W[27 & 0xf] = \
    261                 Wgen (W,27));
    262   SHA2STEP32 (e, f, g, h, a, b, c, d, UINT32_C (0xc6e00bf3), W[28 & 0xf] = \
    263                 Wgen (W,28));
    264   SHA2STEP32 (d, e, f, g, h, a, b, c, UINT32_C (0xd5a79147), W[29 & 0xf] = \
    265                 Wgen (W,29));
    266   SHA2STEP32 (c, d, e, f, g, h, a, b, UINT32_C (0x06ca6351), W[30 & 0xf] = \
    267                 Wgen (W,30));
    268   SHA2STEP32 (b, c, d, e, f, g, h, a, UINT32_C (0x14292967), W[31 & 0xf] = \
    269                 Wgen (W,31));
    270   SHA2STEP32 (a, b, c, d, e, f, g, h, UINT32_C (0x27b70a85), W[32 & 0xf] = \
    271                 Wgen (W,32));
    272   SHA2STEP32 (h, a, b, c, d, e, f, g, UINT32_C (0x2e1b2138), W[33 & 0xf] = \
    273                 Wgen (W,33));
    274   SHA2STEP32 (g, h, a, b, c, d, e, f, UINT32_C (0x4d2c6dfc), W[34 & 0xf] = \
    275                 Wgen (W,34));
    276   SHA2STEP32 (f, g, h, a, b, c, d, e, UINT32_C (0x53380d13), W[35 & 0xf] = \
    277                 Wgen (W,35));
    278   SHA2STEP32 (e, f, g, h, a, b, c, d, UINT32_C (0x650a7354), W[36 & 0xf] = \
    279                 Wgen (W,36));
    280   SHA2STEP32 (d, e, f, g, h, a, b, c, UINT32_C (0x766a0abb), W[37 & 0xf] = \
    281                 Wgen (W,37));
    282   SHA2STEP32 (c, d, e, f, g, h, a, b, UINT32_C (0x81c2c92e), W[38 & 0xf] = \
    283                 Wgen (W,38));
    284   SHA2STEP32 (b, c, d, e, f, g, h, a, UINT32_C (0x92722c85), W[39 & 0xf] = \
    285                 Wgen (W,39));
    286   SHA2STEP32 (a, b, c, d, e, f, g, h, UINT32_C (0xa2bfe8a1), W[40 & 0xf] = \
    287                 Wgen (W,40));
    288   SHA2STEP32 (h, a, b, c, d, e, f, g, UINT32_C (0xa81a664b), W[41 & 0xf] = \
    289                 Wgen (W,41));
    290   SHA2STEP32 (g, h, a, b, c, d, e, f, UINT32_C (0xc24b8b70), W[42 & 0xf] = \
    291                 Wgen (W,42));
    292   SHA2STEP32 (f, g, h, a, b, c, d, e, UINT32_C (0xc76c51a3), W[43 & 0xf] = \
    293                 Wgen (W,43));
    294   SHA2STEP32 (e, f, g, h, a, b, c, d, UINT32_C (0xd192e819), W[44 & 0xf] = \
    295                 Wgen (W,44));
    296   SHA2STEP32 (d, e, f, g, h, a, b, c, UINT32_C (0xd6990624), W[45 & 0xf] = \
    297                 Wgen (W,45));
    298   SHA2STEP32 (c, d, e, f, g, h, a, b, UINT32_C (0xf40e3585), W[46 & 0xf] = \
    299                 Wgen (W,46));
    300   SHA2STEP32 (b, c, d, e, f, g, h, a, UINT32_C (0x106aa070), W[47 & 0xf] = \
    301                 Wgen (W,47));
    302   SHA2STEP32 (a, b, c, d, e, f, g, h, UINT32_C (0x19a4c116), W[48 & 0xf] = \
    303                 Wgen (W,48));
    304   SHA2STEP32 (h, a, b, c, d, e, f, g, UINT32_C (0x1e376c08), W[49 & 0xf] = \
    305                 Wgen (W,49));
    306   SHA2STEP32 (g, h, a, b, c, d, e, f, UINT32_C (0x2748774c), W[50 & 0xf] = \
    307                 Wgen (W,50));
    308   SHA2STEP32 (f, g, h, a, b, c, d, e, UINT32_C (0x34b0bcb5), W[51 & 0xf] = \
    309                 Wgen (W,51));
    310   SHA2STEP32 (e, f, g, h, a, b, c, d, UINT32_C (0x391c0cb3), W[52 & 0xf] = \
    311                 Wgen (W,52));
    312   SHA2STEP32 (d, e, f, g, h, a, b, c, UINT32_C (0x4ed8aa4a), W[53 & 0xf] = \
    313                 Wgen (W,53));
    314   SHA2STEP32 (c, d, e, f, g, h, a, b, UINT32_C (0x5b9cca4f), W[54 & 0xf] = \
    315                 Wgen (W,54));
    316   SHA2STEP32 (b, c, d, e, f, g, h, a, UINT32_C (0x682e6ff3), W[55 & 0xf] = \
    317                 Wgen (W,55));
    318   SHA2STEP32 (a, b, c, d, e, f, g, h, UINT32_C (0x748f82ee), W[56 & 0xf] = \
    319                 Wgen (W,56));
    320   SHA2STEP32 (h, a, b, c, d, e, f, g, UINT32_C (0x78a5636f), W[57 & 0xf] = \
    321                 Wgen (W,57));
    322   SHA2STEP32 (g, h, a, b, c, d, e, f, UINT32_C (0x84c87814), W[58 & 0xf] = \
    323                 Wgen (W,58));
    324   SHA2STEP32 (f, g, h, a, b, c, d, e, UINT32_C (0x8cc70208), W[59 & 0xf] = \
    325                 Wgen (W,59));
    326   SHA2STEP32 (e, f, g, h, a, b, c, d, UINT32_C (0x90befffa), W[60 & 0xf] = \
    327                 Wgen (W,60));
    328   SHA2STEP32 (d, e, f, g, h, a, b, c, UINT32_C (0xa4506ceb), W[61 & 0xf] = \
    329                 Wgen (W,61));
    330   SHA2STEP32 (c, d, e, f, g, h, a, b, UINT32_C (0xbef9a3f7), W[62 & 0xf] = \
    331                 Wgen (W,62));
    332   SHA2STEP32 (b, c, d, e, f, g, h, a, UINT32_C (0xc67178f2), W[63 & 0xf] = \
    333                 Wgen (W,63));
    334 #else  /* ! MHD_FAVOR_SMALL_CODE */
    335   if (1)
    336   {
    337     unsigned int t;
    338     /* K constants array.
    339        See FIPS PUB 180-4 paragraph 4.2.2 for K values. */
    340     static const uint32_t K[80] =
    341     { UINT32_C (0x428a2f98),  UINT32_C (0x71374491),  UINT32_C (0xb5c0fbcf),
    342       UINT32_C (0xe9b5dba5),  UINT32_C (0x3956c25b),  UINT32_C (0x59f111f1),
    343       UINT32_C (0x923f82a4),  UINT32_C (0xab1c5ed5),  UINT32_C (0xd807aa98),
    344       UINT32_C (0x12835b01),  UINT32_C (0x243185be),  UINT32_C (0x550c7dc3),
    345       UINT32_C (0x72be5d74),  UINT32_C (0x80deb1fe),  UINT32_C (0x9bdc06a7),
    346       UINT32_C (0xc19bf174),  UINT32_C (0xe49b69c1),  UINT32_C (0xefbe4786),
    347       UINT32_C (0x0fc19dc6),  UINT32_C (0x240ca1cc),  UINT32_C (0x2de92c6f),
    348       UINT32_C (0x4a7484aa),  UINT32_C (0x5cb0a9dc),  UINT32_C (0x76f988da),
    349       UINT32_C (0x983e5152),  UINT32_C (0xa831c66d),  UINT32_C (0xb00327c8),
    350       UINT32_C (0xbf597fc7),  UINT32_C (0xc6e00bf3),  UINT32_C (0xd5a79147),
    351       UINT32_C (0x06ca6351),  UINT32_C (0x14292967),  UINT32_C (0x27b70a85),
    352       UINT32_C (0x2e1b2138),  UINT32_C (0x4d2c6dfc),  UINT32_C (0x53380d13),
    353       UINT32_C (0x650a7354),  UINT32_C (0x766a0abb),  UINT32_C (0x81c2c92e),
    354       UINT32_C (0x92722c85),  UINT32_C (0xa2bfe8a1),  UINT32_C (0xa81a664b),
    355       UINT32_C (0xc24b8b70),  UINT32_C (0xc76c51a3),  UINT32_C (0xd192e819),
    356       UINT32_C (0xd6990624),  UINT32_C (0xf40e3585),  UINT32_C (0x106aa070),
    357       UINT32_C (0x19a4c116),  UINT32_C (0x1e376c08),  UINT32_C (0x2748774c),
    358       UINT32_C (0x34b0bcb5),  UINT32_C (0x391c0cb3),  UINT32_C (0x4ed8aa4a),
    359       UINT32_C (0x5b9cca4f),  UINT32_C (0x682e6ff3),  UINT32_C (0x748f82ee),
    360       UINT32_C (0x78a5636f),  UINT32_C (0x84c87814),  UINT32_C (0x8cc70208),
    361       UINT32_C (0x90befffa),  UINT32_C (0xa4506ceb),  UINT32_C (0xbef9a3f7),
    362       UINT32_C (0xc67178f2) };
    363     /* One step of SHA-256 computation with working variables rotation,
    364        see FIPS PUB 180-4 paragraph 6.2.2 step 3.
    365      * Note: this version of macro reassign all working variable on
    366              each step. */
    367 #define SHA2STEP32RV(vA,vB,vC,vD,vE,vF,vG,vH,kt,wt) do {              \
    368           uint32_t tmp_h_ = (vH);                                           \
    369           SHA2STEP32 ((vA),(vB),(vC),(vD),(vE),(vF),(vG),tmp_h_,(kt),(wt));  \
    370           (vH) = (vG);                                                      \
    371           (vG) = (vF);                                                      \
    372           (vF) = (vE);                                                      \
    373           (vE) = (vD);                                                      \
    374           (vD) = (vC);                                                      \
    375           (vC) = (vB);                                                      \
    376           (vB) = (vA);                                                      \
    377           (vA) = tmp_h_; \
    378 } \
    379         while (0)
    380 
    381     /* During first 16 steps, before making any calculations on each step,
    382        the W element is read from input data buffer as big-endian value and
    383        stored in array of W elements. */
    384     for (t = 0; t < 16; ++t)
    385     {
    386       SHA2STEP32RV (a, b, c, d, e, f, g, h, K[t], \
    387                     W[t] = GET_W_FROM_DATA (data, t));
    388     }
    389 
    390     /* During last 48 steps, before making any calculations on each step,
    391        current W element is generated from other W elements of the cyclic buffer
    392        and the generated value is stored back in the cyclic buffer. */
    393     for (t = 16; t < 64; ++t)
    394     {
    395       SHA2STEP32RV (a, b, c, d, e, f, g, h, K[t], W[t & 15] = Wgen (W,t));
    396     }
    397   }
    398 #endif /* ! MHD_FAVOR_SMALL_CODE */
    399 
    400   /* Compute intermediate hash.
    401      See FIPS PUB 180-4 paragraph 6.2.2 step 4. */
    402   H[0] += a;
    403   H[1] += b;
    404   H[2] += c;
    405   H[3] += d;
    406   H[4] += e;
    407   H[5] += f;
    408   H[6] += g;
    409   H[7] += h;
    410 }
    411 
    412 
    413 MHD_INTERNAL MHD_FN_PAR_NONNULL_ALL_
    414 MHD_FN_PAR_IN_SIZE_ (3, 2) void
    415 mhd_SHA256_update (struct mhd_Sha256CtxInt *restrict ctx,
    416                    size_t size,
    417                    const uint8_t *restrict data)
    418 {
    419   unsigned bytes_have; /**< Number of bytes in buffer */
    420 
    421   mhd_assert (0 != size);
    422 
    423   /* Note: (count & (mhd_SHA256_BLOCK_SIZE-1))
    424            equals (count % mhd_SHA256_BLOCK_SIZE) for this block size. */
    425   bytes_have = (unsigned) (ctx->count & (mhd_SHA256_BLOCK_SIZE - 1));
    426   ctx->count += size;
    427 
    428   if (0 != bytes_have)
    429   {
    430     unsigned bytes_left = mhd_SHA256_BLOCK_SIZE - bytes_have;
    431     if (size >= bytes_left)
    432     {     /* Combine new data with data in the buffer and
    433              process full block. */
    434       memcpy (((uint8_t *) ctx->buffer) + bytes_have,
    435               data,
    436               bytes_left);
    437       data += bytes_left;
    438       size -= bytes_left;
    439       sha256_transform (ctx->H, ctx->buffer);
    440       bytes_have = 0;
    441     }
    442   }
    443 
    444   while (mhd_SHA256_BLOCK_SIZE <= size)
    445   {   /* Process any full blocks of new data directly,
    446          without copying to the buffer. */
    447     sha256_transform (ctx->H, data);
    448     data += mhd_SHA256_BLOCK_SIZE;
    449     size -= mhd_SHA256_BLOCK_SIZE;
    450   }
    451 
    452   if (0 != size)
    453   {   /* Copy incomplete block of new data (if any)
    454          to the buffer. */
    455     memcpy (((uint8_t *) ctx->buffer) + bytes_have, data, size);
    456   }
    457 }
    458 
    459 
    460 /**
    461  * Size of "length" padding addition in bytes.
    462  * See FIPS PUB 180-4 paragraph 5.1.1.
    463  */
    464 #define SHA256_SIZE_OF_LEN_ADD (64 / 8)
    465 
    466 MHD_INTERNAL MHD_FN_PAR_NONNULL_ALL_ void
    467 mhd_SHA256_finish (struct mhd_Sha256CtxInt *restrict ctx,
    468                    uint8_t digest[mhd_SHA256_DIGEST_SIZE])
    469 {
    470   uint64_t num_bits;   /**< Number of processed bits */
    471   unsigned bytes_have; /**< Number of bytes in buffer */
    472 
    473   num_bits = ctx->count << 3;
    474   /* Note: (count & (mhd_SHA256_BLOCK_SIZE-1))
    475            equal (count % mhd_SHA256_BLOCK_SIZE) for this block size. */
    476   bytes_have = (unsigned) (ctx->count & (mhd_SHA256_BLOCK_SIZE - 1));
    477 
    478   /* Input data must be padded with a single bit "1", then with zeros and
    479      the finally the length of data in bits must be added as the final bytes
    480      of the last block.
    481      See FIPS PUB 180-4 paragraph 5.1.1. */
    482 
    483   /* Data is always processed in form of bytes (not by individual bits),
    484      therefore position of first padding bit in byte is always
    485      predefined (0x80). */
    486   /* Buffer always have space at least for one byte (as full buffers are
    487      processed immediately). */
    488   ((uint8_t *) ctx->buffer)[bytes_have++] = 0x80;
    489 
    490   if (mhd_SHA256_BLOCK_SIZE - bytes_have < SHA256_SIZE_OF_LEN_ADD)
    491   {   /* No space in current block to put total length of message.
    492          Pad current block with zeros and process it. */
    493     if (bytes_have < mhd_SHA256_BLOCK_SIZE)
    494       memset (((uint8_t *) ctx->buffer) + bytes_have, 0,
    495               mhd_SHA256_BLOCK_SIZE - bytes_have);
    496     /* Process full block. */
    497     sha256_transform (ctx->H, ctx->buffer);
    498     /* Start new block. */
    499     bytes_have = 0;
    500   }
    501 
    502   /* Pad the rest of the buffer with zeros. */
    503   memset (((uint8_t *) ctx->buffer) + bytes_have, 0,
    504           mhd_SHA256_BLOCK_SIZE - SHA256_SIZE_OF_LEN_ADD - bytes_have);
    505   /* Put the number of bits in processed message as big-endian value. */
    506   mhd_PUT_64BIT_BE_UNALIGN (ctx->buffer + mhd_SHA256_BLOCK_SIZE_WORDS - 2,
    507                             num_bits);
    508   /* Process full final block. */
    509   sha256_transform (ctx->H, ctx->buffer);
    510 
    511   /* Put final hash/digest in BE mode */
    512   if (1)
    513   {
    514     bool use_tmp_buf_to_align_result;
    515 
    516 #if defined(mhd_PUT_32BIT_BE_UNALIGNED)
    517     use_tmp_buf_to_align_result = false;
    518 #elif defined (MHD_FAVOR_SMALL_CODE)
    519     use_tmp_buf_to_align_result = true; /* smaller code: eliminated branch below */
    520 #else
    521     use_tmp_buf_to_align_result =
    522       (0 != ((uintptr_t) digest) % mhd_UINT32_ALIGN);
    523 #endif
    524     if (use_tmp_buf_to_align_result)
    525     {
    526       /* If storing of the final result requires aligned address and
    527          the destination address is not aligned or compact code is used,
    528          store the final digest in aligned temporary buffer first, then
    529          copy it to the destination. */
    530       uint32_t alig_dgst[mhd_SHA256_DIGEST_SIZE_WORDS];
    531       mhd_PUT_32BIT_BE (alig_dgst + 0, ctx->H[0]);
    532       mhd_PUT_32BIT_BE (alig_dgst + 1, ctx->H[1]);
    533       mhd_PUT_32BIT_BE (alig_dgst + 2, ctx->H[2]);
    534       mhd_PUT_32BIT_BE (alig_dgst + 3, ctx->H[3]);
    535       mhd_PUT_32BIT_BE (alig_dgst + 4, ctx->H[4]);
    536       mhd_PUT_32BIT_BE (alig_dgst + 5, ctx->H[5]);
    537       mhd_PUT_32BIT_BE (alig_dgst + 6, ctx->H[6]);
    538       mhd_PUT_32BIT_BE (alig_dgst + 7, ctx->H[7]);
    539       /* Copy result to unaligned destination address */
    540       memcpy (digest, alig_dgst, mhd_SHA256_DIGEST_SIZE);
    541     }
    542     else
    543     {
    544       /* Use cast to (void*) here to mute compiler alignment warnings.
    545        * Compilers are not smart enough to see that alignment has been checked. */
    546       mhd_PUT_32BIT_BE ((void *) (digest + 0 * mhd_SHA256_BYTES_IN_WORD), \
    547                         ctx->H[0]);
    548       mhd_PUT_32BIT_BE ((void *) (digest + 1 * mhd_SHA256_BYTES_IN_WORD), \
    549                         ctx->H[1]);
    550       mhd_PUT_32BIT_BE ((void *) (digest + 2 * mhd_SHA256_BYTES_IN_WORD), \
    551                         ctx->H[2]);
    552       mhd_PUT_32BIT_BE ((void *) (digest + 3 * mhd_SHA256_BYTES_IN_WORD), \
    553                         ctx->H[3]);
    554       mhd_PUT_32BIT_BE ((void *) (digest + 4 * mhd_SHA256_BYTES_IN_WORD), \
    555                         ctx->H[4]);
    556       mhd_PUT_32BIT_BE ((void *) (digest + 5 * mhd_SHA256_BYTES_IN_WORD), \
    557                         ctx->H[5]);
    558       mhd_PUT_32BIT_BE ((void *) (digest + 6 * mhd_SHA256_BYTES_IN_WORD), \
    559                         ctx->H[6]);
    560       mhd_PUT_32BIT_BE ((void *) (digest + 7 * mhd_SHA256_BYTES_IN_WORD), \
    561                         ctx->H[7]);
    562     }
    563   }
    564 
    565   /* Erase potentially sensitive data. */
    566   memset (ctx, 0, sizeof(struct mhd_Sha256CtxInt));
    567 }
    568 
    569 
    570 mhd_DATA_TRUNCATION_RUNTIME_CHECK_RESTORE