libopkg/sha256.c

   1 /* sha256.c - Functions to compute SHA256 and SHA224 message digest of files or
   2    memory blocks according to the NIST specification FIPS-180-2.
   3
   4    Copyright (C) 2005, 2006, 2008 Free Software Foundation, Inc.
   5
   6    This program is free software: you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation, either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program 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
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  18
  19 /* Written by David Madore, considerably copypasting from
  20    Scott G. Miller's sha1.c
  21 */
  22
  23 #include <config.h>
  24
  25 #include "sha256.h"
  26
  27 #include <stddef.h>
  28 #include <string.h>
  29
  30 #if USE_UNLOCKED_IO
  31 # include "unlocked-io.h"
  32 #endif
  33
  34 #ifdef WORDS_BIGENDIAN
  35 # define SWAP(n) (n)
  36 #else
  37 # define SWAP(n) \
  38     (((n) << 24) | (((n) & 0xff00) << 8) | (((n) >> 8) & 0xff00) | ((n) >> 24))
  39 #endif
  40
  41 #define BLOCKSIZE 4096
  42 #if BLOCKSIZE % 64 != 0
  43 # error "invalid BLOCKSIZE"
  44 #endif
  45
  46 /* This array contains the bytes used to pad the buffer to the next
  47    64-byte boundary.  */
  48 static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ...  */ };
  49
  50
  51 /*
  52   Takes a pointer to a 256 bit block of data (eight 32 bit ints) and
  53   intializes it to the start constants of the SHA256 algorithm.  This
  54   must be called before using hash in the call to sha256_hash
  55 */
  56 void
  57 sha256_init_ctx (struct sha256_ctx *ctx)
  58 {
  59   ctx->state[0] = 0x6a09e667UL;
  60   ctx->state[1] = 0xbb67ae85UL;
  61   ctx->state[2] = 0x3c6ef372UL;
  62   ctx->state[3] = 0xa54ff53aUL;
  63   ctx->state[4] = 0x510e527fUL;
  64   ctx->state[5] = 0x9b05688cUL;
  65   ctx->state[6] = 0x1f83d9abUL;
  66   ctx->state[7] = 0x5be0cd19UL;
  67
  68   ctx->total[0] = ctx->total[1] = 0;
  69   ctx->buflen = 0;
  70 }
  71
  72 void
  73 sha224_init_ctx (struct sha256_ctx *ctx)
  74 {
  75   ctx->state[0] = 0xc1059ed8UL;
  76   ctx->state[1] = 0x367cd507UL;
  77   ctx->state[2] = 0x3070dd17UL;
  78   ctx->state[3] = 0xf70e5939UL;
  79   ctx->state[4] = 0xffc00b31UL;
  80   ctx->state[5] = 0x68581511UL;
  81   ctx->state[6] = 0x64f98fa7UL;
  82   ctx->state[7] = 0xbefa4fa4UL;
  83
  84   ctx->total[0] = ctx->total[1] = 0;
  85   ctx->buflen = 0;
  86 }
  87
  88 /* Copy the value from v into the memory location pointed to by *cp,
  89    If your architecture allows unaligned access this is equivalent to
  90    * (uint32_t *) cp = v  */
  91 static inline void
  92 set_uint32 (char *cp, uint32_t v)
  93 {
  94   memcpy (cp, &v, sizeof v);
  95 }
  96
  97 /* Put result from CTX in first 32 bytes following RESBUF.  The result
  98    must be in little endian byte order.  */
  99 void *
 100 sha256_read_ctx (const struct sha256_ctx *ctx, void *resbuf)
 101 {
 102   int i;
 103   char *r = resbuf;
 104
 105   for (i = 0; i < 8; i++)
 106     set_uint32 (r + i * sizeof ctx->state[0], SWAP (ctx->state[i]));
 107
 108   return resbuf;
 109 }
 110
 111 void *
 112 sha224_read_ctx (const struct sha256_ctx *ctx, void *resbuf)
 113 {
 114   int i;
 115   char *r = resbuf;
 116
 117   for (i = 0; i < 7; i++)
 118     set_uint32 (r + i * sizeof ctx->state[0], SWAP (ctx->state[i]));
 119
 120   return resbuf;
 121 }
 122
 123 /* Process the remaining bytes in the internal buffer and the usual
 124    prolog according to the standard and write the result to RESBUF.  */
 125 static void
 126 sha256_conclude_ctx (struct sha256_ctx *ctx)
 127 {
 128   /* Take yet unprocessed bytes into account.  */
 129   size_t bytes = ctx->buflen;
 130   size_t size = (bytes < 56) ? 64 / 4 : 64 * 2 / 4;
 131
 132   /* Now count remaining bytes.  */
 133   ctx->total[0] += bytes;
 134   if (ctx->total[0] < bytes)
 135     ++ctx->total[1];
 136
 137   /* Put the 64-bit file length in *bits* at the end of the buffer.
 138      Use set_uint32 rather than a simple assignment, to avoid risk of
 139      unaligned access.  */
 140   set_uint32 ((char *) &ctx->buffer[size - 2],
 141               SWAP ((ctx->total[1] << 3) | (ctx->total[0] >> 29)));
 142   set_uint32 ((char *) &ctx->buffer[size - 1],
 143               SWAP (ctx->total[0] << 3));
 144
 145   memcpy (&((char *) ctx->buffer)[bytes], fillbuf, (size - 2) * 4 - bytes);
 146
 147   /* Process last bytes.  */
 148   sha256_process_block (ctx->buffer, size * 4, ctx);
 149 }
 150
 151 void *
 152 sha256_finish_ctx (struct sha256_ctx *ctx, void *resbuf)
 153 {
 154   sha256_conclude_ctx (ctx);
 155   return sha256_read_ctx (ctx, resbuf);
 156 }
 157
 158 void *
 159 sha224_finish_ctx (struct sha256_ctx *ctx, void *resbuf)
 160 {
 161   sha256_conclude_ctx (ctx);
 162   return sha224_read_ctx (ctx, resbuf);
 163 }
 164
 165 /* Compute SHA256 message digest for bytes read from STREAM.  The
 166    resulting message digest number will be written into the 32 bytes
 167    beginning at RESBLOCK.  */
 168 int
 169 sha256_stream (FILE *stream, void *resblock)
 170 {
 171   struct sha256_ctx ctx;
 172   char buffer[BLOCKSIZE + 72];
 173   size_t sum;
 174
 175   /* Initialize the computation context.  */
 176   sha256_init_ctx (&ctx);
 177
 178   /* Iterate over full file contents.  */
 179   while (1)
 180     {
 181       /* We read the file in blocks of BLOCKSIZE bytes.  One call of the
 182          computation function processes the whole buffer so that with the
 183          next round of the loop another block can be read.  */
 184       size_t n;
 185       sum = 0;
 186
 187       /* Read block.  Take care for partial reads.  */
 188       while (1)
 189         {
 190           n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);
 191
 192           sum += n;
 193
 194           if (sum == BLOCKSIZE)
 195             break;
 196
 197           if (n == 0)
 198             {
 199               /* Check for the error flag IFF N == 0, so that we don't
 200                  exit the loop after a partial read due to e.g., EAGAIN
 201                  or EWOULDBLOCK.  */
 202               if (ferror (stream))
 203                 return 1;
 204               goto process_partial_block;
 205             }
 206
 207           /* We've read at least one byte, so ignore errors.  But always
 208              check for EOF, since feof may be true even though N > 0.
 209              Otherwise, we could end up calling fread after EOF.  */
 210           if (feof (stream))
 211             goto process_partial_block;
 212         }
 213
 214       /* Process buffer with BLOCKSIZE bytes.  Note that
 215                         BLOCKSIZE % 64 == 0
 216        */
 217       sha256_process_block (buffer, BLOCKSIZE, &ctx);
 218     }
 219
 220  process_partial_block:;
 221
 222   /* Process any remaining bytes.  */
 223   if (sum > 0)
 224     sha256_process_bytes (buffer, sum, &ctx);
 225
 226   /* Construct result in desired memory.  */
 227   sha256_finish_ctx (&ctx, resblock);
 228   return 0;
 229 }
 230
 231 /* FIXME: Avoid code duplication */
 232 int
 233 sha224_stream (FILE *stream, void *resblock)
 234 {
 235   struct sha256_ctx ctx;
 236   char buffer[BLOCKSIZE + 72];
 237   size_t sum;
 238
 239   /* Initialize the computation context.  */
 240   sha224_init_ctx (&ctx);
 241
 242   /* Iterate over full file contents.  */
 243   while (1)
 244     {
 245       /* We read the file in blocks of BLOCKSIZE bytes.  One call of the
 246          computation function processes the whole buffer so that with the
 247          next round of the loop another block can be read.  */
 248       size_t n;
 249       sum = 0;
 250
 251       /* Read block.  Take care for partial reads.  */
 252       while (1)
 253         {
 254           n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);
 255
 256           sum += n;
 257
 258           if (sum == BLOCKSIZE)
 259             break;
 260
 261           if (n == 0)
 262             {
 263               /* Check for the error flag IFF N == 0, so that we don't
 264                  exit the loop after a partial read due to e.g., EAGAIN
 265                  or EWOULDBLOCK.  */
 266               if (ferror (stream))
 267                 return 1;
 268               goto process_partial_block;
 269             }
 270
 271           /* We've read at least one byte, so ignore errors.  But always
 272              check for EOF, since feof may be true even though N > 0.
 273              Otherwise, we could end up calling fread after EOF.  */
 274           if (feof (stream))
 275             goto process_partial_block;
 276         }
 277
 278       /* Process buffer with BLOCKSIZE bytes.  Note that
 279                         BLOCKSIZE % 64 == 0
 280        */
 281       sha256_process_block (buffer, BLOCKSIZE, &ctx);
 282     }
 283
 284  process_partial_block:;
 285
 286   /* Process any remaining bytes.  */
 287   if (sum > 0)
 288     sha256_process_bytes (buffer, sum, &ctx);
 289
 290   /* Construct result in desired memory.  */
 291   sha224_finish_ctx (&ctx, resblock);
 292   return 0;
 293 }
 294
 295 /* Compute SHA512 message digest for LEN bytes beginning at BUFFER.  The
 296    result is always in little endian byte order, so that a byte-wise
 297    output yields to the wanted ASCII representation of the message
 298    digest.  */
 299 void *
 300 sha256_buffer (const char *buffer, size_t len, void *resblock)
 301 {
 302   struct sha256_ctx ctx;
 303
 304   /* Initialize the computation context.  */
 305   sha256_init_ctx (&ctx);
 306
 307   /* Process whole buffer but last len % 64 bytes.  */
 308   sha256_process_bytes (buffer, len, &ctx);
 309
 310   /* Put result in desired memory area.  */
 311   return sha256_finish_ctx (&ctx, resblock);
 312 }
 313
 314 void *
 315 sha224_buffer (const char *buffer, size_t len, void *resblock)
 316 {
 317   struct sha256_ctx ctx;
 318
 319   /* Initialize the computation context.  */
 320   sha224_init_ctx (&ctx);
 321
 322   /* Process whole buffer but last len % 64 bytes.  */
 323   sha256_process_bytes (buffer, len, &ctx);
 324
 325   /* Put result in desired memory area.  */
 326   return sha224_finish_ctx (&ctx, resblock);
 327 }
 328
 329 void
 330 sha256_process_bytes (const void *buffer, size_t len, struct sha256_ctx *ctx)
 331 {
 332   /* When we already have some bits in our internal buffer concatenate
 333      both inputs first.  */
 334   if (ctx->buflen != 0)
 335     {
 336       size_t left_over = ctx->buflen;
 337       size_t add = 128 - left_over > len ? len : 128 - left_over;
 338
 339       memcpy (&((char *) ctx->buffer)[left_over], buffer, add);
 340       ctx->buflen += add;
 341
 342       if (ctx->buflen > 64)
 343         {
 344           sha256_process_block (ctx->buffer, ctx->buflen & ~63, ctx);
 345
 346           ctx->buflen &= 63;
 347           /* The regions in the following copy operation cannot overlap.  */
 348           memcpy (ctx->buffer,
 349                   &((char *) ctx->buffer)[(left_over + add) & ~63],
 350                   ctx->buflen);
 351         }
 352
 353       buffer = (const char *) buffer + add;
 354       len -= add;
 355     }
 356
 357   /* Process available complete blocks.  */
 358   if (len >= 64)
 359     {
 360 #if !_STRING_ARCH_unaligned
 361 # define alignof(type) offsetof (struct { char c; type x; }, x)
 362 # define UNALIGNED_P(p) (((size_t) p) % alignof (uint32_t) != 0)
 363       if (UNALIGNED_P (buffer))
 364         while (len > 64)
 365           {
 366             sha256_process_block (memcpy (ctx->buffer, buffer, 64), 64, ctx);
 367             buffer = (const char *) buffer + 64;
 368             len -= 64;
 369           }
 370       else
 371 #endif
 372         {
 373           sha256_process_block (buffer, len & ~63, ctx);
 374           buffer = (const char *) buffer + (len & ~63);
 375           len &= 63;
 376         }
 377     }
 378
 379   /* Move remaining bytes in internal buffer.  */
 380   if (len > 0)
 381     {
 382       size_t left_over = ctx->buflen;
 383
 384       memcpy (&((char *) ctx->buffer)[left_over], buffer, len);
 385       left_over += len;
 386       if (left_over >= 64)
 387         {
 388           sha256_process_block (ctx->buffer, 64, ctx);
 389           left_over -= 64;
 390           memcpy (ctx->buffer, &ctx->buffer[16], left_over);
 391         }
 392       ctx->buflen = left_over;
 393     }
 394 }
 395
 396 /* --- Code below is the primary difference between sha1.c and sha256.c --- */
 397
 398 /* SHA256 round constants */
 399 #define K(I) sha256_round_constants[I]
 400 static const uint32_t sha256_round_constants[64] = {
 401   0x428a2f98UL, 0x71374491UL, 0xb5c0fbcfUL, 0xe9b5dba5UL,
 402   0x3956c25bUL, 0x59f111f1UL, 0x923f82a4UL, 0xab1c5ed5UL,
 403   0xd807aa98UL, 0x12835b01UL, 0x243185beUL, 0x550c7dc3UL,
 404   0x72be5d74UL, 0x80deb1feUL, 0x9bdc06a7UL, 0xc19bf174UL,
 405   0xe49b69c1UL, 0xefbe4786UL, 0x0fc19dc6UL, 0x240ca1ccUL,
 406   0x2de92c6fUL, 0x4a7484aaUL, 0x5cb0a9dcUL, 0x76f988daUL,
 407   0x983e5152UL, 0xa831c66dUL, 0xb00327c8UL, 0xbf597fc7UL,
 408   0xc6e00bf3UL, 0xd5a79147UL, 0x06ca6351UL, 0x14292967UL,
 409   0x27b70a85UL, 0x2e1b2138UL, 0x4d2c6dfcUL, 0x53380d13UL,
 410   0x650a7354UL, 0x766a0abbUL, 0x81c2c92eUL, 0x92722c85UL,
 411   0xa2bfe8a1UL, 0xa81a664bUL, 0xc24b8b70UL, 0xc76c51a3UL,
 412   0xd192e819UL, 0xd6990624UL, 0xf40e3585UL, 0x106aa070UL,
 413   0x19a4c116UL, 0x1e376c08UL, 0x2748774cUL, 0x34b0bcb5UL,
 414   0x391c0cb3UL, 0x4ed8aa4aUL, 0x5b9cca4fUL, 0x682e6ff3UL,
 415   0x748f82eeUL, 0x78a5636fUL, 0x84c87814UL, 0x8cc70208UL,
 416   0x90befffaUL, 0xa4506cebUL, 0xbef9a3f7UL, 0xc67178f2UL,
 417 };
 418
 419 /* Round functions.  */
 420 #define F2(A,B,C) ( ( A & B ) | ( C & ( A | B ) ) )
 421 #define F1(E,F,G) ( G ^ ( E & ( F ^ G ) ) )
 422
 423 /* Process LEN bytes of BUFFER, accumulating context into CTX.
 424    It is assumed that LEN % 64 == 0.
 425    Most of this code comes from GnuPG's cipher/sha1.c.  */
 426
 427 void
 428 sha256_process_block (const void *buffer, size_t len, struct sha256_ctx *ctx)
 429 {
 430   const uint32_t *words = buffer;
 431   size_t nwords = len / sizeof (uint32_t);
 432   const uint32_t *endp = words + nwords;
 433   uint32_t x[16];
 434   uint32_t a = ctx->state[0];
 435   uint32_t b = ctx->state[1];
 436   uint32_t c = ctx->state[2];
 437   uint32_t d = ctx->state[3];
 438   uint32_t e = ctx->state[4];
 439   uint32_t f = ctx->state[5];
 440   uint32_t g = ctx->state[6];
 441   uint32_t h = ctx->state[7];
 442
 443   /* First increment the byte count.  FIPS PUB 180-2 specifies the possible
 444      length of the file up to 2^64 bits.  Here we only compute the
 445      number of bytes.  Do a double word increment.  */
 446   ctx->total[0] += len;
 447   if (ctx->total[0] < len)
 448     ++ctx->total[1];
 449
 450 #define rol(x, n) (((x) << (n)) | ((x) >> (32 - (n))))
 451 #define S0(x) (rol(x,25)^rol(x,14)^(x>>3))
 452 #define S1(x) (rol(x,15)^rol(x,13)^(x>>10))
 453 #define SS0(x) (rol(x,30)^rol(x,19)^rol(x,10))
 454 #define SS1(x) (rol(x,26)^rol(x,21)^rol(x,7))
 455
 456 #define M(I) ( tm =   S1(x[(I-2)&0x0f]) + x[(I-7)&0x0f] \
 457                     + S0(x[(I-15)&0x0f]) + x[I&0x0f]    \
 458                , x[I&0x0f] = tm )
 459
 460 #define R(A,B,C,D,E,F,G,H,K,M)  do { t0 = SS0(A) + F2(A,B,C); \
 461                                      t1 = H + SS1(E)  \
 462                                       + F1(E,F,G)     \
 463                                       + K             \
 464                                       + M;            \
 465                                      D += t1;  H = t0 + t1; \
 466                                } while(0)
 467
 468   while (words < endp)
 469     {
 470       uint32_t tm;
 471       uint32_t t0, t1;
 472       int t;
 473       /* FIXME: see sha1.c for a better implementation.  */
 474       for (t = 0; t < 16; t++)
 475         {
 476           x[t] = SWAP (*words);
 477           words++;
 478         }
 479
 480       R( a, b, c, d, e, f, g, h, K( 0), x[ 0] );
 481       R( h, a, b, c, d, e, f, g, K( 1), x[ 1] );
 482       R( g, h, a, b, c, d, e, f, K( 2), x[ 2] );
 483       R( f, g, h, a, b, c, d, e, K( 3), x[ 3] );
 484       R( e, f, g, h, a, b, c, d, K( 4), x[ 4] );
 485       R( d, e, f, g, h, a, b, c, K( 5), x[ 5] );
 486       R( c, d, e, f, g, h, a, b, K( 6), x[ 6] );
 487       R( b, c, d, e, f, g, h, a, K( 7), x[ 7] );
 488       R( a, b, c, d, e, f, g, h, K( 8), x[ 8] );
 489       R( h, a, b, c, d, e, f, g, K( 9), x[ 9] );
 490       R( g, h, a, b, c, d, e, f, K(10), x[10] );
 491       R( f, g, h, a, b, c, d, e, K(11), x[11] );
 492       R( e, f, g, h, a, b, c, d, K(12), x[12] );
 493       R( d, e, f, g, h, a, b, c, K(13), x[13] );
 494       R( c, d, e, f, g, h, a, b, K(14), x[14] );
 495       R( b, c, d, e, f, g, h, a, K(15), x[15] );
 496       R( a, b, c, d, e, f, g, h, K(16), M(16) );
 497       R( h, a, b, c, d, e, f, g, K(17), M(17) );
 498       R( g, h, a, b, c, d, e, f, K(18), M(18) );
 499       R( f, g, h, a, b, c, d, e, K(19), M(19) );
 500       R( e, f, g, h, a, b, c, d, K(20), M(20) );
 501       R( d, e, f, g, h, a, b, c, K(21), M(21) );
 502       R( c, d, e, f, g, h, a, b, K(22), M(22) );
 503       R( b, c, d, e, f, g, h, a, K(23), M(23) );
 504       R( a, b, c, d, e, f, g, h, K(24), M(24) );
 505       R( h, a, b, c, d, e, f, g, K(25), M(25) );
 506       R( g, h, a, b, c, d, e, f, K(26), M(26) );
 507       R( f, g, h, a, b, c, d, e, K(27), M(27) );
 508       R( e, f, g, h, a, b, c, d, K(28), M(28) );
 509       R( d, e, f, g, h, a, b, c, K(29), M(29) );
 510       R( c, d, e, f, g, h, a, b, K(30), M(30) );
 511       R( b, c, d, e, f, g, h, a, K(31), M(31) );
 512       R( a, b, c, d, e, f, g, h, K(32), M(32) );
 513       R( h, a, b, c, d, e, f, g, K(33), M(33) );
 514       R( g, h, a, b, c, d, e, f, K(34), M(34) );
 515       R( f, g, h, a, b, c, d, e, K(35), M(35) );
 516       R( e, f, g, h, a, b, c, d, K(36), M(36) );
 517       R( d, e, f, g, h, a, b, c, K(37), M(37) );
 518       R( c, d, e, f, g, h, a, b, K(38), M(38) );
 519       R( b, c, d, e, f, g, h, a, K(39), M(39) );
 520       R( a, b, c, d, e, f, g, h, K(40), M(40) );
 521       R( h, a, b, c, d, e, f, g, K(41), M(41) );
 522       R( g, h, a, b, c, d, e, f, K(42), M(42) );
 523       R( f, g, h, a, b, c, d, e, K(43), M(43) );
 524       R( e, f, g, h, a, b, c, d, K(44), M(44) );
 525       R( d, e, f, g, h, a, b, c, K(45), M(45) );
 526       R( c, d, e, f, g, h, a, b, K(46), M(46) );
 527       R( b, c, d, e, f, g, h, a, K(47), M(47) );
 528       R( a, b, c, d, e, f, g, h, K(48), M(48) );
 529       R( h, a, b, c, d, e, f, g, K(49), M(49) );
 530       R( g, h, a, b, c, d, e, f, K(50), M(50) );
 531       R( f, g, h, a, b, c, d, e, K(51), M(51) );
 532       R( e, f, g, h, a, b, c, d, K(52), M(52) );
 533       R( d, e, f, g, h, a, b, c, K(53), M(53) );
 534       R( c, d, e, f, g, h, a, b, K(54), M(54) );
 535       R( b, c, d, e, f, g, h, a, K(55), M(55) );
 536       R( a, b, c, d, e, f, g, h, K(56), M(56) );
 537       R( h, a, b, c, d, e, f, g, K(57), M(57) );
 538       R( g, h, a, b, c, d, e, f, K(58), M(58) );
 539       R( f, g, h, a, b, c, d, e, K(59), M(59) );
 540       R( e, f, g, h, a, b, c, d, K(60), M(60) );
 541       R( d, e, f, g, h, a, b, c, K(61), M(61) );
 542       R( c, d, e, f, g, h, a, b, K(62), M(62) );
 543       R( b, c, d, e, f, g, h, a, K(63), M(63) );
 544
 545       a = ctx->state[0] += a;
 546       b = ctx->state[1] += b;
 547       c = ctx->state[2] += c;
 548       d = ctx->state[3] += d;
 549       e = ctx->state[4] += e;
 550       f = ctx->state[5] += f;
 551       g = ctx->state[6] += g;
 552       h = ctx->state[7] += h;
 553     }
 554 }