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) 2007-2013 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    <http://www.gnu.org/licenses/>.  */
  19
  20 /* Written by Ulrich Drepper <drepper@redhat.com>, 2007.  */
  21
  22 #ifdef HAVE_CONFIG_H
  23 # include <config.h>
  24 #endif
  25
  26 #include <endian.h>
  27 #include <stdlib.h>
  28 #include <string.h>
  29 #include <stdint.h>
  30 #include <sys/types.h>
  31
  32 #include "sha256.h"
  33
  34 #if __BYTE_ORDER == __LITTLE_ENDIAN
  35 # ifdef _LIBC
  36 #  include <byteswap.h>
  37 #  define SWAP(n) bswap_32 (n)
  38 #  define SWAP64(n) bswap_64 (n)
  39 # else
  40 #  define SWAP(n) \
  41     (((n) << 24) | (((n) & 0xff00) << 8) | (((n) >> 8) & 0xff00) | ((n) >> 24))
  42 #  define SWAP64(n) \
  43   (((n) << 56)                                  \
  44    | (((n) & 0xff00) << 40)                     \
  45    | (((n) & 0xff0000) << 24)                   \
  46    | (((n) & 0xff000000) << 8)                  \
  47    | (((n) >> 8) & 0xff000000)                  \
  48    | (((n) >> 24) & 0xff0000)                   \
  49    | (((n) >> 40) & 0xff00)                     \
  50    | ((n) >> 56))
  51 # endif
  52 #else
  53 # define SWAP(n) (n)
  54 # define SWAP64(n) (n)
  55 #endif
  56
  57
  58 /* This array contains the bytes used to pad the buffer to the next
  59    64-byte boundary.  (FIPS 180-2:5.1.1)  */
  60 static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ...  */ };
  61
  62
  63 /* Constants for SHA256 from FIPS 180-2:4.2.2.  */
  64 static const uint32_t K[64] =
  65   {
  66     0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
  67     0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
  68     0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
  69     0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
  70     0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
  71     0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
  72     0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
  73     0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
  74     0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
  75     0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
  76     0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
  77     0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
  78     0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
  79     0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
  80     0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
  81     0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
  82   };
  83
  84 void
  85 sha256_process_block (const void *, size_t, struct sha256_ctx *);
  86
  87 /* Initialize structure containing state of computation.
  88    (FIPS 180-2:5.3.2)  */
  89 void
  90 __sha256_init_ctx (ctx)
  91      struct sha256_ctx *ctx;
  92 {
  93   ctx->H[0] = 0x6a09e667;
  94   ctx->H[1] = 0xbb67ae85;
  95   ctx->H[2] = 0x3c6ef372;
  96   ctx->H[3] = 0xa54ff53a;
  97   ctx->H[4] = 0x510e527f;
  98   ctx->H[5] = 0x9b05688c;
  99   ctx->H[6] = 0x1f83d9ab;
 100   ctx->H[7] = 0x5be0cd19;
 101
 102   ctx->total64 = 0;
 103   ctx->buflen = 0;
 104 }
 105
 106
 107 /* Process the remaining bytes in the internal buffer and the usual
 108    prolog according to the standard and write the result to RESBUF.
 109
 110    IMPORTANT: On some systems it is required that RESBUF is correctly
 111    aligned for a 32 bits value.  */
 112 void *
 113 __sha256_finish_ctx (ctx, resbuf)
 114      struct sha256_ctx *ctx;
 115      void *resbuf;
 116 {
 117   /* Take yet unprocessed bytes into account.  */
 118   uint32_t bytes = ctx->buflen;
 119   size_t pad;
 120
 121   /* Now count remaining bytes.  */
 122   ctx->total64 += bytes;
 123
 124   pad = bytes >= 56 ? 64 + 56 - bytes : 56 - bytes;
 125   memcpy (&ctx->buffer[bytes], fillbuf, pad);
 126
 127   /* Put the 64-bit file length in *bits* at the end of the buffer.  */
 128 #ifdef _STRING_ARCH_unaligned
 129   ctx->buffer64[(bytes + pad) / 8] = SWAP64 (ctx->total64 << 3);
 130 #else
 131   ctx->buffer32[(bytes + pad + 4) / 4] = SWAP (ctx->total[TOTAL64_low] << 3);
 132   ctx->buffer32[(bytes + pad) / 4] = SWAP ((ctx->total[TOTAL64_high] << 3) |
 133                                            (ctx->total[TOTAL64_low] >> 29));
 134 #endif
 135
 136   /* Process last bytes.  */
 137   sha256_process_block (ctx->buffer, bytes + pad + 8, ctx);
 138
 139   /* Put result from CTX in first 32 bytes following RESBUF.  */
 140   for (unsigned int i = 0; i < 8; ++i)
 141     ((uint32_t *) resbuf)[i] = SWAP (ctx->H[i]);
 142
 143   return resbuf;
 144 }
 145
 146
 147 void
 148 __sha256_process_bytes (buffer, len, ctx)
 149      const void *buffer;
 150      size_t len;
 151      struct sha256_ctx *ctx;
 152 {
 153   /* When we already have some bits in our internal buffer concatenate
 154      both inputs first.  */
 155   if (ctx->buflen != 0)
 156     {
 157       size_t left_over = ctx->buflen;
 158       size_t add = 128 - left_over > len ? len : 128 - left_over;
 159
 160       memcpy (&ctx->buffer[left_over], buffer, add);
 161       ctx->buflen += add;
 162
 163       if (ctx->buflen > 64)
 164         {
 165           sha256_process_block (ctx->buffer, ctx->buflen & ~63, ctx);
 166
 167           ctx->buflen &= 63;
 168           /* The regions in the following copy operation cannot overlap.  */
 169           memcpy (ctx->buffer, &ctx->buffer[(left_over + add) & ~63],
 170                   ctx->buflen);
 171         }
 172
 173       buffer = (const char *) buffer + add;
 174       len -= add;
 175     }
 176
 177   /* Process available complete blocks.  */
 178   if (len >= 64)
 179     {
 180 #if !_STRING_ARCH_unaligned
 181 /* To check alignment gcc has an appropriate operator.  Other
 182    compilers don't.  */
 183 # if __GNUC__ >= 2
 184 #  define UNALIGNED_P(p) (((uintptr_t) p) % __alignof__ (uint32_t) != 0)
 185 # else
 186 #  define UNALIGNED_P(p) (((uintptr_t) p) % sizeof (uint32_t) != 0)
 187 # endif
 188       if (UNALIGNED_P (buffer))
 189         while (len > 64)
 190           {
 191             sha256_process_block (memcpy (ctx->buffer, buffer, 64), 64, ctx);
 192             buffer = (const char *) buffer + 64;
 193             len -= 64;
 194           }
 195       else
 196 #endif
 197         {
 198           sha256_process_block (buffer, len & ~63, ctx);
 199           buffer = (const char *) buffer + (len & ~63);
 200           len &= 63;
 201         }
 202     }
 203
 204   /* Move remaining bytes into internal buffer.  */
 205   if (len > 0)
 206     {
 207       size_t left_over = ctx->buflen;
 208
 209       memcpy (&ctx->buffer[left_over], buffer, len);
 210       left_over += len;
 211       if (left_over >= 64)
 212         {
 213           sha256_process_block (ctx->buffer, 64, ctx);
 214           left_over -= 64;
 215           memcpy (ctx->buffer, &ctx->buffer[64], left_over);
 216         }
 217       ctx->buflen = left_over;
 218     }
 219 }
 220
 221 #include <sha256-block.c>