crypt/sha256.c

   1 /* Functions to compute SHA256 message digest of files or memory blocks.
   2    according to the definition of SHA256 in FIPS 180-2.
   3    Copyright (C) 2007-2023 Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library 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    The GNU C Library 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    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <https://www.gnu.org/licenses/>.  */
  19
  20
  21 #ifdef HAVE_CONFIG_H
  22 # include <config.h>
  23 #endif
  24
  25 #include <endian.h>
  26 #include <stdlib.h>
  27 #include <string.h>
  28 #include <stdint.h>
  29 #include <sys/types.h>
  30
  31 #include "sha256.h"
  32
  33 #if __BYTE_ORDER == __LITTLE_ENDIAN
  34 # ifdef _LIBC
  35 #  include <byteswap.h>
  36 #  define SWAP(n) bswap_32 (n)
  37 #  define SWAP64(n) bswap_64 (n)
  38 # else
  39 #  define SWAP(n) \
  40     (((n) << 24) | (((n) & 0xff00) << 8) | (((n) >> 8) & 0xff00) | ((n) >> 24))
  41 #  define SWAP64(n) \
  42   (((n) << 56)                                  \
  43    | (((n) & 0xff00) << 40)                     \
  44    | (((n) & 0xff0000) << 24)                   \
  45    | (((n) & 0xff000000) << 8)                  \
  46    | (((n) >> 8) & 0xff000000)                  \
  47    | (((n) >> 24) & 0xff0000)                   \
  48    | (((n) >> 40) & 0xff00)                     \
  49    | ((n) >> 56))
  50 # endif
  51 #else
  52 # define SWAP(n) (n)
  53 # define SWAP64(n) (n)
  54 #endif
  55
  56
  57 /* This array contains the bytes used to pad the buffer to the next
  58    64-byte boundary.  (FIPS 180-2:5.1.1)  */
  59 static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ...  */ };
  60
  61
  62 /* Constants for SHA256 from FIPS 180-2:4.2.2.  */
  63 static const uint32_t K[64] =
  64   {
  65     0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
  66     0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
  67     0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
  68     0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
  69     0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
  70     0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
  71     0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
  72     0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
  73     0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
  74     0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
  75     0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
  76     0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
  77     0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
  78     0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
  79     0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
  80     0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
  81   };
  82
  83 void __sha256_process_block (const void *, size_t, struct sha256_ctx *);
  84
  85 /* Initialize structure containing state of computation.
  86    (FIPS 180-2:5.3.2)  */
  87 void
  88 __sha256_init_ctx (struct sha256_ctx *ctx)
  89 {
  90   ctx->H[0] = 0x6a09e667;
  91   ctx->H[1] = 0xbb67ae85;
  92   ctx->H[2] = 0x3c6ef372;
  93   ctx->H[3] = 0xa54ff53a;
  94   ctx->H[4] = 0x510e527f;
  95   ctx->H[5] = 0x9b05688c;
  96   ctx->H[6] = 0x1f83d9ab;
  97   ctx->H[7] = 0x5be0cd19;
  98
  99   ctx->total64 = 0;
 100   ctx->buflen = 0;
 101 }
 102
 103
 104 /* Process the remaining bytes in the internal buffer and the usual
 105    prolog according to the standard and write the result to RESBUF.
 106
 107    IMPORTANT: On some systems it is required that RESBUF is correctly
 108    aligned for a 32 bits value.  */
 109 void *
 110 __sha256_finish_ctx (struct sha256_ctx *ctx, void *resbuf)
 111 {
 112   /* Take yet unprocessed bytes into account.  */
 113   uint32_t bytes = ctx->buflen;
 114   size_t pad;
 115
 116   /* Now count remaining bytes.  */
 117   ctx->total64 += bytes;
 118
 119   pad = bytes >= 56 ? 64 + 56 - bytes : 56 - bytes;
 120   memcpy (&ctx->buffer[bytes], fillbuf, pad);
 121
 122   /* Put the 64-bit file length in *bits* at the end of the buffer.  */
 123   ctx->buffer32[(bytes + pad + 4) / 4] = SWAP (ctx->total[TOTAL64_low] << 3);
 124   ctx->buffer32[(bytes + pad) / 4] = SWAP ((ctx->total[TOTAL64_high] << 3)
 125                                            | (ctx->total[TOTAL64_low] >> 29));
 126
 127   /* Process last bytes.  */
 128   __sha256_process_block (ctx->buffer, bytes + pad + 8, ctx);
 129
 130   /* Put result from CTX in first 32 bytes following RESBUF.  */
 131   for (unsigned int i = 0; i < 8; ++i)
 132     ((uint32_t *) resbuf)[i] = SWAP (ctx->H[i]);
 133
 134   return resbuf;
 135 }
 136
 137
 138 void
 139 __sha256_process_bytes (const void *buffer, size_t len, struct sha256_ctx *ctx)
 140 {
 141   /* When we already have some bits in our internal buffer concatenate
 142      both inputs first.  */
 143   if (ctx->buflen != 0)
 144     {
 145       size_t left_over = ctx->buflen;
 146       size_t add = 128 - left_over > len ? len : 128 - left_over;
 147
 148       memcpy (&ctx->buffer[left_over], buffer, add);
 149       ctx->buflen += add;
 150
 151       if (ctx->buflen > 64)
 152         {
 153           __sha256_process_block (ctx->buffer, ctx->buflen & ~63, ctx);
 154
 155           ctx->buflen &= 63;
 156           /* The regions in the following copy operation cannot overlap.  */
 157           memcpy (ctx->buffer, &ctx->buffer[(left_over + add) & ~63],
 158                   ctx->buflen);
 159         }
 160
 161       buffer = (const char *) buffer + add;
 162       len -= add;
 163     }
 164
 165   /* Process available complete blocks.  */
 166   if (len >= 64)
 167     {
 168       while (len > 64)
 169         {
 170           __sha256_process_block (memcpy (ctx->buffer, buffer, 64), 64, ctx);
 171           buffer = (const char *) buffer + 64;
 172           len -= 64;
 173         }
 174     }
 175
 176   /* Move remaining bytes into internal buffer.  */
 177   if (len > 0)
 178     {
 179       size_t left_over = ctx->buflen;
 180
 181       memcpy (&ctx->buffer[left_over], buffer, len);
 182       left_over += len;
 183       if (left_over >= 64)
 184         {
 185           __sha256_process_block (ctx->buffer, 64, ctx);
 186           left_over -= 64;
 187           memcpy (ctx->buffer, &ctx->buffer[64], left_over);
 188         }
 189       ctx->buflen = left_over;
 190     }
 191 }
 192
 193 #include <sha256-block.c>