crypt/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) 1995,1996,1997,1999,2000,2001,2005
   4         Free Software Foundation, Inc.
   5    This file is part of the GNU C Library.
   6
   7    The GNU C Library is free software; you can redistribute it and/or
   8    modify it under the terms of the GNU Lesser General Public
   9    License as published by the Free Software Foundation; either
  10    version 2.1 of the License, or (at your option) any later version.
  11
  12    The GNU C Library 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 GNU
  15    Lesser General Public License for more details.
  16
  17    You should have received a copy of the GNU Lesser General Public
  18    License along with the GNU C Library; if not, write to the Free
  19    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  20    02111-1307 USA.  */
  21
  22 /* Written by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1995.  */
  23
  24 #ifdef HAVE_CONFIG_H
  25 # include <config.h>
  26 #endif
  27
  28 #include <sys/types.h>
  29
  30 #if STDC_HEADERS || defined _LIBC
  31 # include <stdlib.h>
  32 # include <string.h>
  33 #else
  34 # ifndef HAVE_MEMCPY
  35 #  define memcpy(d, s, n) (bcopy ((s), (d), (n)), (d))
  36 # endif
  37 #endif
  38
  39 #include "md5.h"
  40
  41 #ifdef _LIBC
  42 # include <endian.h>
  43 # if __BYTE_ORDER == __BIG_ENDIAN
  44 #  define WORDS_BIGENDIAN 1
  45 # endif
  46 /* We need to keep the namespace clean so define the MD5 function
  47    protected using leading __ .  */
  48 # define md5_init_ctx __md5_init_ctx
  49 # define md5_process_block __md5_process_block
  50 # define md5_process_bytes __md5_process_bytes
  51 # define md5_finish_ctx __md5_finish_ctx
  52 # define md5_read_ctx __md5_read_ctx
  53 # define md5_stream __md5_stream
  54 # define md5_buffer __md5_buffer
  55 #endif
  56
  57 #ifdef WORDS_BIGENDIAN
  58 # define SWAP(n)                                                        \
  59     (((n) << 24) | (((n) & 0xff00) << 8) | (((n) >> 8) & 0xff00) | ((n) >> 24))
  60 #else
  61 # define SWAP(n) (n)
  62 #endif
  63
  64
  65 /* This array contains the bytes used to pad the buffer to the next
  66    64-byte boundary.  (RFC 1321, 3.1: Step 1)  */
  67 static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ...  */ };
  68
  69
  70 /* Initialize structure containing state of computation.
  71    (RFC 1321, 3.3: Step 3)  */
  72 void
  73 md5_init_ctx (ctx)
  74      struct md5_ctx *ctx;
  75 {
  76   ctx->A = 0x67452301;
  77   ctx->B = 0xefcdab89;
  78   ctx->C = 0x98badcfe;
  79   ctx->D = 0x10325476;
  80
  81   ctx->total[0] = ctx->total[1] = 0;
  82   ctx->buflen = 0;
  83 }
  84
  85 /* Put result from CTX in first 16 bytes following RESBUF.  The result
  86    must be in little endian byte order.
  87
  88    IMPORTANT: On some systems it is required that RESBUF is correctly
  89    aligned for a 32 bits value.  */
  90 void *
  91 md5_read_ctx (ctx, resbuf)
  92      const struct md5_ctx *ctx;
  93      void *resbuf;
  94 {
  95   ((md5_uint32 *) resbuf)[0] = SWAP (ctx->A);
  96   ((md5_uint32 *) resbuf)[1] = SWAP (ctx->B);
  97   ((md5_uint32 *) resbuf)[2] = SWAP (ctx->C);
  98   ((md5_uint32 *) resbuf)[3] = SWAP (ctx->D);
  99
 100   return resbuf;
 101 }
 102
 103 /* Process the remaining bytes in the internal buffer and the usual
 104    prolog according to the standard and write the result to RESBUF.
 105
 106    IMPORTANT: On some systems it is required that RESBUF is correctly
 107    aligned for a 32 bits value.  */
 108 void *
 109 md5_finish_ctx (ctx, resbuf)
 110      struct md5_ctx *ctx;
 111      void *resbuf;
 112 {
 113   /* Take yet unprocessed bytes into account.  */
 114   md5_uint32 bytes = ctx->buflen;
 115   size_t pad;
 116
 117   /* Now count remaining bytes.  */
 118   ctx->total[0] += bytes;
 119   if (ctx->total[0] < bytes)
 120     ++ctx->total[1];
 121
 122   pad = bytes >= 56 ? 64 + 56 - bytes : 56 - bytes;
 123   memcpy (&ctx->buffer[bytes], fillbuf, pad);
 124
 125   /* Put the 64-bit file length in *bits* at the end of the buffer.  */
 126   *(md5_uint32 *) &ctx->buffer[bytes + pad] = SWAP (ctx->total[0] << 3);
 127   *(md5_uint32 *) &ctx->buffer[bytes + pad + 4] = SWAP ((ctx->total[1] << 3) |
 128                                                         (ctx->total[0] >> 29));
 129
 130   /* Process last bytes.  */
 131   md5_process_block (ctx->buffer, bytes + pad + 8, ctx);
 132
 133   return md5_read_ctx (ctx, resbuf);
 134 }
 135
 136 /* Compute MD5 message digest for bytes read from STREAM.  The
 137    resulting message digest number will be written into the 16 bytes
 138    beginning at RESBLOCK.  */
 139 int
 140 md5_stream (stream, resblock)
 141      FILE *stream;
 142      void *resblock;
 143 {
 144   /* Important: BLOCKSIZE must be a multiple of 64.  */
 145 #define BLOCKSIZE 4096
 146   struct md5_ctx ctx;
 147   char buffer[BLOCKSIZE + 72];
 148   size_t sum;
 149
 150   /* Initialize the computation context.  */
 151   md5_init_ctx (&ctx);
 152
 153   /* Iterate over full file contents.  */
 154   while (1)
 155     {
 156       /* We read the file in blocks of BLOCKSIZE bytes.  One call of the
 157          computation function processes the whole buffer so that with the
 158          next round of the loop another block can be read.  */
 159       size_t n;
 160       sum = 0;
 161
 162       /* Read block.  Take care for partial reads.  */
 163       do
 164         {
 165           n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);
 166
 167           sum += n;
 168         }
 169       while (sum < BLOCKSIZE && n != 0);
 170       if (n == 0 && ferror (stream))
 171         return 1;
 172
 173       /* If end of file is reached, end the loop.  */
 174       if (n == 0)
 175         break;
 176
 177       /* Process buffer with BLOCKSIZE bytes.  Note that
 178                         BLOCKSIZE % 64 == 0
 179        */
 180       md5_process_block (buffer, BLOCKSIZE, &ctx);
 181     }
 182
 183   /* Add the last bytes if necessary.  */
 184   if (sum > 0)
 185     md5_process_bytes (buffer, sum, &ctx);
 186
 187   /* Construct result in desired memory.  */
 188   md5_finish_ctx (&ctx, resblock);
 189   return 0;
 190 }
 191
 192 /* Compute MD5 message digest for LEN bytes beginning at BUFFER.  The
 193    result is always in little endian byte order, so that a byte-wise
 194    output yields to the wanted ASCII representation of the message
 195    digest.  */
 196 void *
 197 md5_buffer (buffer, len, resblock)
 198      const char *buffer;
 199      size_t len;
 200      void *resblock;
 201 {
 202   struct md5_ctx ctx;
 203
 204   /* Initialize the computation context.  */
 205   md5_init_ctx (&ctx);
 206
 207   /* Process whole buffer but last len % 64 bytes.  */
 208   md5_process_bytes (buffer, len, &ctx);
 209
 210   /* Put result in desired memory area.  */
 211   return md5_finish_ctx (&ctx, resblock);
 212 }
 213
 214
 215 void
 216 md5_process_bytes (buffer, len, ctx)
 217      const void *buffer;
 218      size_t len;
 219      struct md5_ctx *ctx;
 220 {
 221   /* When we already have some bits in our internal buffer concatenate
 222      both inputs first.  */
 223   if (ctx->buflen != 0)
 224     {
 225       size_t left_over = ctx->buflen;
 226       size_t add = 128 - left_over > len ? len : 128 - left_over;
 227
 228       memcpy (&ctx->buffer[left_over], buffer, add);
 229       ctx->buflen += add;
 230
 231       if (ctx->buflen > 64)
 232         {
 233           md5_process_block (ctx->buffer, ctx->buflen & ~63, ctx);
 234
 235           ctx->buflen &= 63;
 236           /* The regions in the following copy operation cannot overlap.  */
 237           memcpy (ctx->buffer, &ctx->buffer[(left_over + add) & ~63],
 238                   ctx->buflen);
 239         }
 240
 241       buffer = (const char *) buffer + add;
 242       len -= add;
 243     }
 244
 245   /* Process available complete blocks.  */
 246   if (len >= 64)
 247     {
 248 #if !_STRING_ARCH_unaligned
 249 /* To check alignment gcc has an appropriate operator.  Other
 250    compilers don't.  */
 251 # if __GNUC__ >= 2
 252 #  define UNALIGNED_P(p) (((md5_uintptr) p) % __alignof__ (md5_uint32) != 0)
 253 # else
 254 #  define UNALIGNED_P(p) (((md5_uintptr) p) % sizeof (md5_uint32) != 0)
 255 # endif
 256       if (UNALIGNED_P (buffer))
 257         while (len > 64)
 258           {
 259             md5_process_block (memcpy (ctx->buffer, buffer, 64), 64, ctx);
 260             buffer = (const char *) buffer + 64;
 261             len -= 64;
 262           }
 263       else
 264 #endif
 265         {
 266           md5_process_block (buffer, len & ~63, ctx);
 267           buffer = (const char *) buffer + (len & ~63);
 268           len &= 63;
 269         }
 270     }
 271
 272   /* Move remaining bytes in internal buffer.  */
 273   if (len > 0)
 274     {
 275       size_t left_over = ctx->buflen;
 276
 277       memcpy (&ctx->buffer[left_over], buffer, len);
 278       left_over += len;
 279       if (left_over >= 64)
 280         {
 281           md5_process_block (ctx->buffer, 64, ctx);
 282           left_over -= 64;
 283           memcpy (ctx->buffer, &ctx->buffer[64], left_over);
 284         }
 285       ctx->buflen = left_over;
 286     }
 287 }
 288
 289
 290 /* These are the four functions used in the four steps of the MD5 algorithm
 291    and defined in the RFC 1321.  The first function is a little bit optimized
 292    (as found in Colin Plumbs public domain implementation).  */
 293 /* #define FF(b, c, d) ((b & c) | (~b & d)) */
 294 #define FF(b, c, d) (d ^ (b & (c ^ d)))
 295 #define FG(b, c, d) FF (d, b, c)
 296 #define FH(b, c, d) (b ^ c ^ d)
 297 #define FI(b, c, d) (c ^ (b | ~d))
 298
 299 /* Process LEN bytes of BUFFER, accumulating context into CTX.
 300    It is assumed that LEN % 64 == 0.  */
 301
 302 void
 303 md5_process_block (buffer, len, ctx)
 304      const void *buffer;
 305      size_t len;
 306      struct md5_ctx *ctx;
 307 {
 308   md5_uint32 correct_words[16];
 309   const md5_uint32 *words = buffer;
 310   size_t nwords = len / sizeof (md5_uint32);
 311   const md5_uint32 *endp = words + nwords;
 312   md5_uint32 A = ctx->A;
 313   md5_uint32 B = ctx->B;
 314   md5_uint32 C = ctx->C;
 315   md5_uint32 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       md5_uint32 *cwp = correct_words;
 329       md5_uint32 A_save = A;
 330       md5_uint32 B_save = B;
 331       md5_uint32 C_save = C;
 332       md5_uint32 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
 361       /* Round 1.  */
 362       OP (A, B, C, D,  7, 0xd76aa478);
 363       OP (D, A, B, C, 12, 0xe8c7b756);
 364       OP (C, D, A, B, 17, 0x242070db);
 365       OP (B, C, D, A, 22, 0xc1bdceee);
 366       OP (A, B, C, D,  7, 0xf57c0faf);
 367       OP (D, A, B, C, 12, 0x4787c62a);
 368       OP (C, D, A, B, 17, 0xa8304613);
 369       OP (B, C, D, A, 22, 0xfd469501);
 370       OP (A, B, C, D,  7, 0x698098d8);
 371       OP (D, A, B, C, 12, 0x8b44f7af);
 372       OP (C, D, A, B, 17, 0xffff5bb1);
 373       OP (B, C, D, A, 22, 0x895cd7be);
 374       OP (A, B, C, D,  7, 0x6b901122);
 375       OP (D, A, B, C, 12, 0xfd987193);
 376       OP (C, D, A, B, 17, 0xa679438e);
 377       OP (B, C, D, A, 22, 0x49b40821);
 378
 379       /* For the second to fourth round we have the possibly swapped words
 380          in CORRECT_WORDS.  Redefine the macro to take an additional first
 381          argument specifying the function to use.  */
 382 #undef OP
 383 #define OP(f, a, b, c, d, k, s, T)                                      \
 384       do                                                                \
 385         {                                                               \
 386           a += f (b, c, d) + correct_words[k] + T;                      \
 387           CYCLIC (a, s);                                                \
 388           a += b;                                                       \
 389         }                                                               \
 390       while (0)
 391
 392       /* Round 2.  */
 393       OP (FG, A, B, C, D,  1,  5, 0xf61e2562);
 394       OP (FG, D, A, B, C,  6,  9, 0xc040b340);
 395       OP (FG, C, D, A, B, 11, 14, 0x265e5a51);
 396       OP (FG, B, C, D, A,  0, 20, 0xe9b6c7aa);
 397       OP (FG, A, B, C, D,  5,  5, 0xd62f105d);
 398       OP (FG, D, A, B, C, 10,  9, 0x02441453);
 399       OP (FG, C, D, A, B, 15, 14, 0xd8a1e681);
 400       OP (FG, B, C, D, A,  4, 20, 0xe7d3fbc8);
 401       OP (FG, A, B, C, D,  9,  5, 0x21e1cde6);
 402       OP (FG, D, A, B, C, 14,  9, 0xc33707d6);
 403       OP (FG, C, D, A, B,  3, 14, 0xf4d50d87);
 404       OP (FG, B, C, D, A,  8, 20, 0x455a14ed);
 405       OP (FG, A, B, C, D, 13,  5, 0xa9e3e905);
 406       OP (FG, D, A, B, C,  2,  9, 0xfcefa3f8);
 407       OP (FG, C, D, A, B,  7, 14, 0x676f02d9);
 408       OP (FG, B, C, D, A, 12, 20, 0x8d2a4c8a);
 409
 410       /* Round 3.  */
 411       OP (FH, A, B, C, D,  5,  4, 0xfffa3942);
 412       OP (FH, D, A, B, C,  8, 11, 0x8771f681);
 413       OP (FH, C, D, A, B, 11, 16, 0x6d9d6122);
 414       OP (FH, B, C, D, A, 14, 23, 0xfde5380c);
 415       OP (FH, A, B, C, D,  1,  4, 0xa4beea44);
 416       OP (FH, D, A, B, C,  4, 11, 0x4bdecfa9);
 417       OP (FH, C, D, A, B,  7, 16, 0xf6bb4b60);
 418       OP (FH, B, C, D, A, 10, 23, 0xbebfbc70);
 419       OP (FH, A, B, C, D, 13,  4, 0x289b7ec6);
 420       OP (FH, D, A, B, C,  0, 11, 0xeaa127fa);
 421       OP (FH, C, D, A, B,  3, 16, 0xd4ef3085);
 422       OP (FH, B, C, D, A,  6, 23, 0x04881d05);
 423       OP (FH, A, B, C, D,  9,  4, 0xd9d4d039);
 424       OP (FH, D, A, B, C, 12, 11, 0xe6db99e5);
 425       OP (FH, C, D, A, B, 15, 16, 0x1fa27cf8);
 426       OP (FH, B, C, D, A,  2, 23, 0xc4ac5665);
 427
 428       /* Round 4.  */
 429       OP (FI, A, B, C, D,  0,  6, 0xf4292244);
 430       OP (FI, D, A, B, C,  7, 10, 0x432aff97);
 431       OP (FI, C, D, A, B, 14, 15, 0xab9423a7);
 432       OP (FI, B, C, D, A,  5, 21, 0xfc93a039);
 433       OP (FI, A, B, C, D, 12,  6, 0x655b59c3);
 434       OP (FI, D, A, B, C,  3, 10, 0x8f0ccc92);
 435       OP (FI, C, D, A, B, 10, 15, 0xffeff47d);
 436       OP (FI, B, C, D, A,  1, 21, 0x85845dd1);
 437       OP (FI, A, B, C, D,  8,  6, 0x6fa87e4f);
 438       OP (FI, D, A, B, C, 15, 10, 0xfe2ce6e0);
 439       OP (FI, C, D, A, B,  6, 15, 0xa3014314);
 440       OP (FI, B, C, D, A, 13, 21, 0x4e0811a1);
 441       OP (FI, A, B, C, D,  4,  6, 0xf7537e82);
 442       OP (FI, D, A, B, C, 11, 10, 0xbd3af235);
 443       OP (FI, C, D, A, B,  2, 15, 0x2ad7d2bb);
 444       OP (FI, B, C, D, A,  9, 21, 0xeb86d391);
 445
 446       /* Add the starting values of the context.  */
 447       A += A_save;
 448       B += B_save;
 449       C += C_save;
 450       D += D_save;
 451     }
 452
 453   /* Put checksum in context given as argument.  */
 454   ctx->A = A;
 455   ctx->B = B;
 456   ctx->C = C;
 457   ctx->D = D;
 458 }