lib/md5.c

   1 /* Functions to compute MD5 message digest of files or memory blocks.
   2    according to the definition of MD5 in RFC 1321 from April 1992.
   3    Copyright (C) 1995-1997, 1999-2001, 2005-2006, 2008-2011 Free Software
   4    Foundation, Inc.
   5    This file is part of the GNU C Library.
   6
   7    This program is free software; you can redistribute it and/or modify it
   8    under the terms of the GNU General Public License as published by the
   9    Free Software Foundation; either version 3, or (at your option) any
  10    later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, write to the Free Software Foundation,
  19    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
  20
  21 /* Written by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1995.  */
  22
  23 #include <config.h>
  24
  25 #include "md5.h"
  26
  27 #include <stddef.h>
  28 #include <stdlib.h>
  29 #include <string.h>
  30 #include <sys/types.h>
  31
  32 #if USE_UNLOCKED_IO
  33 # include "unlocked-io.h"
  34 #endif
  35
  36 #ifdef _LIBC
  37 # include <endian.h>
  38 # if __BYTE_ORDER == __BIG_ENDIAN
  39 #  define WORDS_BIGENDIAN 1
  40 # endif
  41 /* We need to keep the namespace clean so define the MD5 function
  42    protected using leading __ .  */
  43 # define md5_init_ctx __md5_init_ctx
  44 # define md5_process_block __md5_process_block
  45 # define md5_process_bytes __md5_process_bytes
  46 # define md5_finish_ctx __md5_finish_ctx
  47 # define md5_read_ctx __md5_read_ctx
  48 # define md5_stream __md5_stream
  49 # define md5_buffer __md5_buffer
  50 #endif
  51
  52 #ifdef WORDS_BIGENDIAN
  53 # define SWAP(n)                                                        \
  54     (((n) << 24) | (((n) & 0xff00) << 8) | (((n) >> 8) & 0xff00) | ((n) >> 24))
  55 #else
  56 # define SWAP(n) (n)
  57 #endif
  58
  59 #define BLOCKSIZE 32768
  60 #if BLOCKSIZE % 64 != 0
  61 # error "invalid BLOCKSIZE"
  62 #endif
  63
  64 /* This array contains the bytes used to pad the buffer to the next
  65    64-byte boundary.  (RFC 1321, 3.1: Step 1)  */
  66 static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ...  */ };
  67
  68
  69 /* Initialize structure containing state of computation.
  70    (RFC 1321, 3.3: Step 3)  */
  71 void
  72 md5_init_ctx (struct md5_ctx *ctx)
  73 {
  74   ctx->A = 0x67452301;
  75   ctx->B = 0xefcdab89;
  76   ctx->C = 0x98badcfe;
  77   ctx->D = 0x10325476;
  78
  79   ctx->total[0] = ctx->total[1] = 0;
  80   ctx->buflen = 0;
  81 }
  82
  83 /* Copy the 4 byte value from v into the memory location pointed to by *cp,
  84    If your architecture allows unaligned access this is equivalent to
  85    * (uint32_t *) cp = v  */
  86 static inline void
  87 set_uint32 (char *cp, uint32_t v)
  88 {
  89   memcpy (cp, &v, sizeof v);
  90 }
  91
  92 /* Put result from CTX in first 16 bytes following RESBUF.  The result
  93    must be in little endian byte order.  */
  94 void *
  95 md5_read_ctx (const struct md5_ctx *ctx, void *resbuf)
  96 {
  97   char *r = resbuf;
  98   set_uint32 (r + 0 * sizeof ctx->A, SWAP (ctx->A));
  99   set_uint32 (r + 1 * sizeof ctx->B, SWAP (ctx->B));
 100   set_uint32 (r + 2 * sizeof ctx->C, SWAP (ctx->C));
 101   set_uint32 (r + 3 * sizeof ctx->D, SWAP (ctx->D));
 102
 103   return resbuf;
 104 }
 105
 106 /* Process the remaining bytes in the internal buffer and the usual
 107    prolog according to the standard and write the result to RESBUF.  */
 108 void *
 109 md5_finish_ctx (struct md5_ctx *ctx, void *resbuf)
 110 {
 111   /* Take yet unprocessed bytes into account.  */
 112   uint32_t bytes = ctx->buflen;
 113   size_t size = (bytes < 56) ? 64 / 4 : 64 * 2 / 4;
 114
 115   /* Now count remaining bytes.  */
 116   ctx->total[0] += bytes;
 117   if (ctx->total[0] < bytes)
 118     ++ctx->total[1];
 119
 120   /* Put the 64-bit file length in *bits* at the end of the buffer.  */
 121   ctx->buffer[size - 2] = SWAP (ctx->total[0] << 3);
 122   ctx->buffer[size - 1] = SWAP ((ctx->total[1] << 3) | (ctx->total[0] >> 29));
 123
 124   memcpy (&((char *) ctx->buffer)[bytes], fillbuf, (size - 2) * 4 - bytes);
 125
 126   /* Process last bytes.  */
 127   md5_process_block (ctx->buffer, size * 4, ctx);
 128
 129   return md5_read_ctx (ctx, resbuf);
 130 }
 131
 132 /* Compute MD5 message digest for bytes read from STREAM.  The
 133    resulting message digest number will be written into the 16 bytes
 134    beginning at RESBLOCK.  */
 135 int
 136 md5_stream (FILE *stream, void *resblock)
 137 {
 138   struct md5_ctx ctx;
 139   size_t sum;
 140
 141   char *buffer = malloc (BLOCKSIZE + 72);
 142   if (!buffer)
 143     return 1;
 144
 145   /* Initialize the computation context.  */
 146   md5_init_ctx (&ctx);
 147
 148   /* Iterate over full file contents.  */
 149   while (1)
 150     {
 151       /* We read the file in blocks of BLOCKSIZE bytes.  One call of the
 152          computation function processes the whole buffer so that with the
 153          next round of the loop another block can be read.  */
 154       size_t n;
 155       sum = 0;
 156
 157       /* Read block.  Take care for partial reads.  */
 158       while (1)
 159         {
 160           n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);
 161
 162           sum += n;
 163
 164           if (sum == BLOCKSIZE)
 165             break;
 166
 167           if (n == 0)
 168             {
 169               /* Check for the error flag IFF N == 0, so that we don't
 170                  exit the loop after a partial read due to e.g., EAGAIN
 171                  or EWOULDBLOCK.  */
 172               if (ferror (stream))
 173                 {
 174                   free (buffer);
 175                   return 1;
 176                 }
 177               goto process_partial_block;
 178             }
 179
 180           /* We've read at least one byte, so ignore errors.  But always
 181              check for EOF, since feof may be true even though N > 0.
 182              Otherwise, we could end up calling fread after EOF.  */
 183           if (feof (stream))
 184             goto process_partial_block;
 185         }
 186
 187       /* Process buffer with BLOCKSIZE bytes.  Note that
 188          BLOCKSIZE % 64 == 0
 189        */
 190       md5_process_block (buffer, BLOCKSIZE, &ctx);
 191     }
 192
 193 process_partial_block:
 194
 195   /* Process any remaining bytes.  */
 196   if (sum > 0)
 197     md5_process_bytes (buffer, sum, &ctx);
 198
 199   /* Construct result in desired memory.  */
 200   md5_finish_ctx (&ctx, resblock);
 201   free (buffer);
 202   return 0;
 203 }
 204
 205 /* Compute MD5 message digest for LEN bytes beginning at BUFFER.  The
 206    result is always in little endian byte order, so that a byte-wise
 207    output yields to the wanted ASCII representation of the message
 208    digest.  */
 209 void *
 210 md5_buffer (const char *buffer, size_t len, void *resblock)
 211 {
 212   struct md5_ctx ctx;
 213
 214   /* Initialize the computation context.  */
 215   md5_init_ctx (&ctx);
 216
 217   /* Process whole buffer but last len % 64 bytes.  */
 218   md5_process_bytes (buffer, len, &ctx);
 219
 220   /* Put result in desired memory area.  */
 221   return md5_finish_ctx (&ctx, resblock);
 222 }
 223
 224
 225 void
 226 md5_process_bytes (const void *buffer, size_t len, struct md5_ctx *ctx)
 227 {
 228   /* When we already have some bits in our internal buffer concatenate
 229      both inputs first.  */
 230   if (ctx->buflen != 0)
 231     {
 232       size_t left_over = ctx->buflen;
 233       size_t add = 128 - left_over > len ? len : 128 - left_over;
 234
 235       memcpy (&((char *) ctx->buffer)[left_over], buffer, add);
 236       ctx->buflen += add;
 237
 238       if (ctx->buflen > 64)
 239         {
 240           md5_process_block (ctx->buffer, ctx->buflen & ~63, ctx);
 241
 242           ctx->buflen &= 63;
 243           /* The regions in the following copy operation cannot overlap.  */
 244           memcpy (ctx->buffer,
 245                   &((char *) ctx->buffer)[(left_over + add) & ~63],
 246                   ctx->buflen);
 247         }
 248
 249       buffer = (const char *) buffer + add;
 250       len -= add;
 251     }
 252
 253   /* Process available complete blocks.  */
 254   if (len >= 64)
 255     {
 256 #if !_STRING_ARCH_unaligned
 257 # define alignof(type) offsetof (struct { char c; type x; }, x)
 258 # define UNALIGNED_P(p) (((size_t) p) % alignof (uint32_t) != 0)
 259       if (UNALIGNED_P (buffer))
 260         while (len > 64)
 261           {
 262             md5_process_block (memcpy (ctx->buffer, buffer, 64), 64, ctx);
 263             buffer = (const char *) buffer + 64;
 264             len -= 64;
 265           }
 266       else
 267 #endif
 268         {
 269           md5_process_block (buffer, len & ~63, ctx);
 270           buffer = (const char *) buffer + (len & ~63);
 271           len &= 63;
 272         }
 273     }
 274
 275   /* Move remaining bytes in internal buffer.  */
 276   if (len > 0)
 277     {
 278       size_t left_over = ctx->buflen;
 279
 280       memcpy (&((char *) ctx->buffer)[left_over], buffer, len);
 281       left_over += len;
 282       if (left_over >= 64)
 283         {
 284           md5_process_block (ctx->buffer, 64, ctx);
 285           left_over -= 64;
 286           memcpy (ctx->buffer, &ctx->buffer[16], left_over);
 287         }
 288       ctx->buflen = left_over;
 289     }
 290 }
 291
 292
 293 /* These are the four functions used in the four steps of the MD5 algorithm
 294    and defined in the RFC 1321.  The first function is a little bit optimized
 295    (as found in Colin Plumbs public domain implementation).  */
 296 /* #define FF(b, c, d) ((b & c) | (~b & d)) */
 297 #define FF(b, c, d) (d ^ (b & (c ^ d)))
 298 #define FG(b, c, d) FF (d, b, c)
 299 #define FH(b, c, d) (b ^ c ^ d)
 300 #define FI(b, c, d) (c ^ (b | ~d))
 301
 302 /* Process LEN bytes of BUFFER, accumulating context into CTX.
 303    It is assumed that LEN % 64 == 0.  */
 304
 305 void
 306 md5_process_block (const void *buffer, size_t len, struct md5_ctx *ctx)
 307 {
 308   uint32_t correct_words[16];
 309   const uint32_t *words = buffer;
 310   size_t nwords = len / sizeof (uint32_t);
 311   const uint32_t *endp = words + nwords;
 312   uint32_t A = ctx->A;
 313   uint32_t B = ctx->B;
 314   uint32_t C = ctx->C;
 315   uint32_t D = ctx->D;
 316
 317   /* First increment the byte count.  RFC 1321 specifies the possible
 318      length of the file up to 2^64 bits.  Here we only compute the
 319      number of bytes.  Do a double word increment.  */
 320   ctx->total[0] += len;
 321   if (ctx->total[0] < len)
 322     ++ctx->total[1];
 323
 324   /* Process all bytes in the buffer with 64 bytes in each round of
 325      the loop.  */
 326   while (words < endp)
 327     {
 328       uint32_t *cwp = correct_words;
 329       uint32_t A_save = A;
 330       uint32_t B_save = B;
 331       uint32_t C_save = C;
 332       uint32_t D_save = D;
 333
 334       /* First round: using the given function, the context and a constant
 335          the next context is computed.  Because the algorithms processing
 336          unit is a 32-bit word and it is determined to work on words in
 337          little endian byte order we perhaps have to change the byte order
 338          before the computation.  To reduce the work for the next steps
 339          we store the swapped words in the array CORRECT_WORDS.  */
 340
 341 #define OP(a, b, c, d, s, T)                                            \
 342       do                                                                \
 343         {                                                               \
 344           a += FF (b, c, d) + (*cwp++ = SWAP (*words)) + T;             \
 345           ++words;                                                      \
 346           CYCLIC (a, s);                                                \
 347           a += b;                                                       \
 348         }                                                               \
 349       while (0)
 350
 351       /* It is unfortunate that C does not provide an operator for
 352          cyclic rotation.  Hope the C compiler is smart enough.  */
 353 #define CYCLIC(w, s) (w = (w << s) | (w >> (32 - s)))
 354
 355       /* Before we start, one word to the strange constants.
 356          They are defined in RFC 1321 as
 357
 358          T[i] = (int) (4294967296.0 * fabs (sin (i))), i=1..64
 359
 360          Here is an equivalent invocation using Perl:
 361
 362          perl -e 'foreach(1..64){printf "0x%08x\n", int (4294967296 * abs (sin $_))}'
 363        */
 364
 365       /* Round 1.  */
 366       OP (A, B, C, D, 7, 0xd76aa478);
 367       OP (D, A, B, C, 12, 0xe8c7b756);
 368       OP (C, D, A, B, 17, 0x242070db);
 369       OP (B, C, D, A, 22, 0xc1bdceee);
 370       OP (A, B, C, D, 7, 0xf57c0faf);
 371       OP (D, A, B, C, 12, 0x4787c62a);
 372       OP (C, D, A, B, 17, 0xa8304613);
 373       OP (B, C, D, A, 22, 0xfd469501);
 374       OP (A, B, C, D, 7, 0x698098d8);
 375       OP (D, A, B, C, 12, 0x8b44f7af);
 376       OP (C, D, A, B, 17, 0xffff5bb1);
 377       OP (B, C, D, A, 22, 0x895cd7be);
 378       OP (A, B, C, D, 7, 0x6b901122);
 379       OP (D, A, B, C, 12, 0xfd987193);
 380       OP (C, D, A, B, 17, 0xa679438e);
 381       OP (B, C, D, A, 22, 0x49b40821);
 382
 383       /* For the second to fourth round we have the possibly swapped words
 384          in CORRECT_WORDS.  Redefine the macro to take an additional first
 385          argument specifying the function to use.  */
 386 #undef OP
 387 #define OP(f, a, b, c, d, k, s, T)                                      \
 388       do                                                                \
 389         {                                                               \
 390           a += f (b, c, d) + correct_words[k] + T;                      \
 391           CYCLIC (a, s);                                                \
 392           a += b;                                                       \
 393         }                                                               \
 394       while (0)
 395
 396       /* Round 2.  */
 397       OP (FG, A, B, C, D, 1, 5, 0xf61e2562);
 398       OP (FG, D, A, B, C, 6, 9, 0xc040b340);
 399       OP (FG, C, D, A, B, 11, 14, 0x265e5a51);
 400       OP (FG, B, C, D, A, 0, 20, 0xe9b6c7aa);
 401       OP (FG, A, B, C, D, 5, 5, 0xd62f105d);
 402       OP (FG, D, A, B, C, 10, 9, 0x02441453);
 403       OP (FG, C, D, A, B, 15, 14, 0xd8a1e681);
 404       OP (FG, B, C, D, A, 4, 20, 0xe7d3fbc8);
 405       OP (FG, A, B, C, D, 9, 5, 0x21e1cde6);
 406       OP (FG, D, A, B, C, 14, 9, 0xc33707d6);
 407       OP (FG, C, D, A, B, 3, 14, 0xf4d50d87);
 408       OP (FG, B, C, D, A, 8, 20, 0x455a14ed);
 409       OP (FG, A, B, C, D, 13, 5, 0xa9e3e905);
 410       OP (FG, D, A, B, C, 2, 9, 0xfcefa3f8);
 411       OP (FG, C, D, A, B, 7, 14, 0x676f02d9);
 412       OP (FG, B, C, D, A, 12, 20, 0x8d2a4c8a);
 413
 414       /* Round 3.  */
 415       OP (FH, A, B, C, D, 5, 4, 0xfffa3942);
 416       OP (FH, D, A, B, C, 8, 11, 0x8771f681);
 417       OP (FH, C, D, A, B, 11, 16, 0x6d9d6122);
 418       OP (FH, B, C, D, A, 14, 23, 0xfde5380c);
 419       OP (FH, A, B, C, D, 1, 4, 0xa4beea44);
 420       OP (FH, D, A, B, C, 4, 11, 0x4bdecfa9);
 421       OP (FH, C, D, A, B, 7, 16, 0xf6bb4b60);
 422       OP (FH, B, C, D, A, 10, 23, 0xbebfbc70);
 423       OP (FH, A, B, C, D, 13, 4, 0x289b7ec6);
 424       OP (FH, D, A, B, C, 0, 11, 0xeaa127fa);
 425       OP (FH, C, D, A, B, 3, 16, 0xd4ef3085);
 426       OP (FH, B, C, D, A, 6, 23, 0x04881d05);
 427       OP (FH, A, B, C, D, 9, 4, 0xd9d4d039);
 428       OP (FH, D, A, B, C, 12, 11, 0xe6db99e5);
 429       OP (FH, C, D, A, B, 15, 16, 0x1fa27cf8);
 430       OP (FH, B, C, D, A, 2, 23, 0xc4ac5665);
 431
 432       /* Round 4.  */
 433       OP (FI, A, B, C, D, 0, 6, 0xf4292244);
 434       OP (FI, D, A, B, C, 7, 10, 0x432aff97);
 435       OP (FI, C, D, A, B, 14, 15, 0xab9423a7);
 436       OP (FI, B, C, D, A, 5, 21, 0xfc93a039);
 437       OP (FI, A, B, C, D, 12, 6, 0x655b59c3);
 438       OP (FI, D, A, B, C, 3, 10, 0x8f0ccc92);
 439       OP (FI, C, D, A, B, 10, 15, 0xffeff47d);
 440       OP (FI, B, C, D, A, 1, 21, 0x85845dd1);
 441       OP (FI, A, B, C, D, 8, 6, 0x6fa87e4f);
 442       OP (FI, D, A, B, C, 15, 10, 0xfe2ce6e0);
 443       OP (FI, C, D, A, B, 6, 15, 0xa3014314);
 444       OP (FI, B, C, D, A, 13, 21, 0x4e0811a1);
 445       OP (FI, A, B, C, D, 4, 6, 0xf7537e82);
 446       OP (FI, D, A, B, C, 11, 10, 0xbd3af235);
 447       OP (FI, C, D, A, B, 2, 15, 0x2ad7d2bb);
 448       OP (FI, B, C, D, A, 9, 21, 0xeb86d391);
 449
 450       /* Add the starting values of the context.  */
 451       A += A_save;
 452       B += B_save;
 453       C += C_save;
 454       D += D_save;
 455     }
 456
 457   /* Put checksum in context given as argument.  */
 458   ctx->A = A;
 459   ctx->B = B;
 460   ctx->C = C;
 461   ctx->D = D;
 462 }