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 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, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 /* Written by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1995.  */
  22
  23 #ifdef HAVE_CONFIG_H
  24 # include <config.h>
  25 #endif
  26
  27 #include <sys/types.h>
  28
  29 #if STDC_HEADERS || defined _LIBC
  30 # include <stdlib.h>
  31 # include <string.h>
  32 #else
  33 # ifndef HAVE_MEMCPY
  34 #  define memcpy(d, s, n) bcopy ((s), (d), (n))
  35 # endif
  36 #endif
  37
  38 #include "md5.h"
  39
  40 #ifdef _LIBC
  41 # include <endian.h>
  42 # if __BYTE_ORDER == __BIG_ENDIAN
  43 #  define WORDS_BIGENDIAN 1
  44 # endif
  45 /* We need to keep the namespace clean so define the MD5 function
  46    protected using leading __ .  */
  47 # define md5_init_ctx __md5_init_ctx
  48 # define md5_process_block __md5_process_block
  49 # define md5_process_bytes __md5_process_bytes
  50 # define md5_finish_ctx __md5_finish_ctx
  51 # define md5_read_ctx __md5_read_ctx
  52 # define md5_stream __md5_stream
  53 # define md5_buffer __md5_buffer
  54 #endif
  55
  56 #ifdef WORDS_BIGENDIAN
  57 # define SWAP(n)                                                        \
  58     (((n) << 24) | (((n) & 0xff00) << 8) | (((n) >> 8) & 0xff00) | ((n) >> 24))
  59 #else
  60 # define SWAP(n) (n)
  61 #endif
  62
  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 (ctx)
  73      struct md5_ctx *ctx;
  74 {
  75   ctx->A = 0x67452301;
  76   ctx->B = 0xefcdab89;
  77   ctx->C = 0x98badcfe;
  78   ctx->D = 0x10325476;
  79
  80   ctx->total[0] = ctx->total[1] = 0;
  81   ctx->buflen = 0;
  82 }
  83
  84 /* Put result from CTX in first 16 bytes following RESBUF.  The result
  85    must be in little endian byte order.
  86
  87    IMPORTANT: On some systems it is required that RESBUF is correctly
  88    aligned for a 32 bits value.  */
  89 void *
  90 md5_read_ctx (ctx, resbuf)
  91      const struct md5_ctx *ctx;
  92      void *resbuf;
  93 {
  94   ((md5_uint32 *) resbuf)[0] = SWAP (ctx->A);
  95   ((md5_uint32 *) resbuf)[1] = SWAP (ctx->B);
  96   ((md5_uint32 *) resbuf)[2] = SWAP (ctx->C);
  97   ((md5_uint32 *) resbuf)[3] = SWAP (ctx->D);
  98
  99   return resbuf;
 100 }
 101
 102 /* Process the remaining bytes in the internal buffer and the usual
 103    prolog according to the standard and write the result to RESBUF.
 104
 105    IMPORTANT: On some systems it is required that RESBUF is correctly
 106    aligned for a 32 bits value.  */
 107 void *
 108 md5_finish_ctx (ctx, resbuf)
 109      struct md5_ctx *ctx;
 110      void *resbuf;
 111 {
 112   /* Take yet unprocessed bytes into account.  */
 113   md5_uint32 bytes = ctx->buflen;
 114   size_t pad;
 115
 116   /* Now count remaining bytes.  */
 117   ctx->total[0] += bytes;
 118   if (ctx->total[0] < bytes)
 119     ++ctx->total[1];
 120
 121   pad = bytes >= 56 ? 64 + 56 - bytes : 56 - bytes;
 122   memcpy (&ctx->buffer[bytes], fillbuf, pad);
 123
 124   /* Put the 64-bit file length in *bits* at the end of the buffer.  */
 125   *(md5_uint32 *) &ctx->buffer[bytes + pad] = SWAP (ctx->total[0] << 3);
 126   *(md5_uint32 *) &ctx->buffer[bytes + pad + 4] = SWAP ((ctx->total[1] << 3) |
 127                                                         (ctx->total[0] >> 29));
 128
 129   /* Process last bytes.  */
 130   md5_process_block (ctx->buffer, bytes + pad + 8, ctx);
 131
 132   return md5_read_ctx (ctx, resbuf);
 133 }
 134
 135 /* Compute MD5 message digest for bytes read from STREAM.  The
 136    resulting message digest number will be written into the 16 bytes
 137    beginning at RESBLOCK.  */
 138 int
 139 md5_stream (stream, resblock)
 140      FILE *stream;
 141      void *resblock;
 142 {
 143   /* Important: BLOCKSIZE must be a multiple of 64.  */
 144 #define BLOCKSIZE 4096
 145   struct md5_ctx ctx;
 146   char buffer[BLOCKSIZE + 72];
 147   size_t sum;
 148
 149   /* Initialize the computation context.  */
 150   md5_init_ctx (&ctx);
 151
 152   /* Iterate over full file contents.  */
 153   while (1)
 154     {
 155       /* We read the file in blocks of BLOCKSIZE bytes.  One call of the
 156          computation function processes the whole buffer so that with the
 157          next round of the loop another block can be read.  */
 158       size_t n;
 159       sum = 0;
 160
 161       /* Read block.  Take care for partial reads.  */
 162       do
 163         {
 164           n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);
 165
 166           sum += n;
 167         }
 168       while (sum < BLOCKSIZE && n != 0);
 169       if (n == 0 && ferror (stream))
 170         return 1;
 171
 172       /* If end of file is reached, end the loop.  */
 173       if (n == 0)
 174         break;
 175
 176       /* Process buffer with BLOCKSIZE bytes.  Note that
 177                         BLOCKSIZE % 64 == 0
 178        */
 179       md5_process_block (buffer, BLOCKSIZE, &ctx);
 180     }
 181
 182   /* Add the last bytes if necessary.  */
 183   if (sum > 0)
 184     md5_process_bytes (buffer, sum, &ctx);
 185
 186   /* Construct result in desired memory.  */
 187   md5_finish_ctx (&ctx, resblock);
 188   return 0;
 189 }
 190
 191 /* Compute MD5 message digest for LEN bytes beginning at BUFFER.  The
 192    result is always in little endian byte order, so that a byte-wise
 193    output yields to the wanted ASCII representation of the message
 194    digest.  */
 195 void *
 196 md5_buffer (buffer, len, resblock)
 197      const char *buffer;
 198      size_t len;
 199      void *resblock;
 200 {
 201   struct md5_ctx ctx;
 202
 203   /* Initialize the computation context.  */
 204   md5_init_ctx (&ctx);
 205
 206   /* Process whole buffer but last len % 64 bytes.  */
 207   md5_process_bytes (buffer, len, &ctx);
 208
 209   /* Put result in desired memory area.  */
 210   return md5_finish_ctx (&ctx, resblock);
 211 }
 212
 213
 214 void
 215 md5_process_bytes (buffer, len, ctx)
 216      const void *buffer;
 217      size_t len;
 218      struct md5_ctx *ctx;
 219 {
 220   /* When we already have some bits in our internal buffer concatenate
 221      both inputs first.  */
 222   if (ctx->buflen != 0)
 223     {
 224       size_t left_over = ctx->buflen;
 225       size_t add = 128 - left_over > len ? len : 128 - left_over;
 226
 227       memcpy (&ctx->buffer[left_over], buffer, add);
 228       ctx->buflen += add;
 229
 230       if (ctx->buflen > 64)
 231         {
 232           md5_process_block (ctx->buffer, ctx->buflen & ~63, ctx);
 233
 234           ctx->buflen &= 63;
 235           /* The regions in the following copy operation cannot overlap.  */
 236           memcpy (ctx->buffer, &ctx->buffer[(left_over + add) & ~63],
 237                   ctx->buflen);
 238         }
 239
 240       buffer = (const char *) buffer + add;
 241       len -= add;
 242     }
 243
 244   /* Process available complete blocks.  */
 245   if (len >= 64)
 246     {
 247 #if !_STRING_ARCH_unaligned
 248 /* To check alignment gcc has an appropriate operator.  Other
 249    compilers don't.  */
 250 # if __GNUC__ >= 2
 251 #  define UNALIGNED_P(p) (((md5_uintptr) p) % __alignof__ (md5_uint32) != 0)
 252 # else
 253 #  define UNALIGNED_P(p) (((md5_uintptr) p) % sizeof (md5_uint32) != 0)
 254 # endif
 255       if (UNALIGNED_P (buffer))
 256         while (len > 64)
 257           {
 258             md5_process_block (memcpy (ctx->buffer, buffer, 64), 64, ctx);
 259             buffer = (const char *) buffer + 64;
 260             len -= 64;
 261           }
 262       else
 263 #endif
 264         {
 265           md5_process_block (buffer, len & ~63, ctx);
 266           buffer = (const char *) buffer + (len & ~63);
 267           len &= 63;
 268         }
 269     }
 270
 271   /* Move remaining bytes in internal buffer.  */
 272   if (len > 0)
 273     {
 274       size_t left_over = ctx->buflen;
 275
 276       memcpy (&ctx->buffer[left_over], buffer, len);
 277       left_over += len;
 278       if (left_over >= 64)
 279         {
 280           md5_process_block (ctx->buffer, 64, ctx);
 281           left_over -= 64;
 282           memcpy (ctx->buffer, &ctx->buffer[64], left_over);
 283         }
 284       ctx->buflen = left_over;
 285     }
 286 }
 287
 288
 289 /* These are the four functions used in the four steps of the MD5 algorithm
 290    and defined in the RFC 1321.  The first function is a little bit optimized
 291    (as found in Colin Plumbs public domain implementation).  */
 292 /* #define FF(b, c, d) ((b & c) | (~b & d)) */
 293 #define FF(b, c, d) (d ^ (b & (c ^ d)))
 294 #define FG(b, c, d) FF (d, b, c)
 295 #define FH(b, c, d) (b ^ c ^ d)
 296 #define FI(b, c, d) (c ^ (b | ~d))
 297
 298 /* Process LEN bytes of BUFFER, accumulating context into CTX.
 299    It is assumed that LEN % 64 == 0.  */
 300
 301 void
 302 md5_process_block (buffer, len, ctx)
 303      const void *buffer;
 304      size_t len;
 305      struct md5_ctx *ctx;
 306 {
 307   md5_uint32 correct_words[16];
 308   const md5_uint32 *words = buffer;
 309   size_t nwords = len / sizeof (md5_uint32);
 310   const md5_uint32 *endp = words + nwords;
 311   md5_uint32 A = ctx->A;
 312   md5_uint32 B = ctx->B;
 313   md5_uint32 C = ctx->C;
 314   md5_uint32 D = ctx->D;
 315
 316   /* First increment the byte count.  RFC 1321 specifies the possible
 317      length of the file up to 2^64 bits.  Here we only compute the
 318      number of bytes.  Do a double word increment.  */
 319   ctx->total[0] += len;
 320   if (ctx->total[0] < len)
 321     ++ctx->total[1];
 322
 323   /* Process all bytes in the buffer with 64 bytes in each round of
 324      the loop.  */
 325   while (words < endp)
 326     {
 327       md5_uint32 *cwp = correct_words;
 328       md5_uint32 A_save = A;
 329       md5_uint32 B_save = B;
 330       md5_uint32 C_save = C;
 331       md5_uint32 D_save = D;
 332
 333       /* First round: using the given function, the context and a constant
 334          the next context is computed.  Because the algorithms processing
 335          unit is a 32-bit word and it is determined to work on words in
 336          little endian byte order we perhaps have to change the byte order
 337          before the computation.  To reduce the work for the next steps
 338          we store the swapped words in the array CORRECT_WORDS.  */
 339
 340 #define OP(a, b, c, d, s, T)                                            \
 341       do                                                                \
 342         {                                                               \
 343           a += FF (b, c, d) + (*cwp++ = SWAP (*words)) + T;             \
 344           ++words;                                                      \
 345           CYCLIC (a, s);                                                \
 346           a += b;                                                       \
 347         }                                                               \
 348       while (0)
 349
 350       /* It is unfortunate that C does not provide an operator for
 351          cyclic rotation.  Hope the C compiler is smart enough.  */
 352 #define CYCLIC(w, s) (w = (w << s) | (w >> (32 - s)))
 353
 354       /* Before we start, one word to the strange constants.
 355          They are defined in RFC 1321 as
 356
 357          T[i] = (int) (4294967296.0 * fabs (sin (i))), i=1..64
 358        */
 359
 360       /* Round 1.  */
 361       OP (A, B, C, D,  7, 0xd76aa478);
 362       OP (D, A, B, C, 12, 0xe8c7b756);
 363       OP (C, D, A, B, 17, 0x242070db);
 364       OP (B, C, D, A, 22, 0xc1bdceee);
 365       OP (A, B, C, D,  7, 0xf57c0faf);
 366       OP (D, A, B, C, 12, 0x4787c62a);
 367       OP (C, D, A, B, 17, 0xa8304613);
 368       OP (B, C, D, A, 22, 0xfd469501);
 369       OP (A, B, C, D,  7, 0x698098d8);
 370       OP (D, A, B, C, 12, 0x8b44f7af);
 371       OP (C, D, A, B, 17, 0xffff5bb1);
 372       OP (B, C, D, A, 22, 0x895cd7be);
 373       OP (A, B, C, D,  7, 0x6b901122);
 374       OP (D, A, B, C, 12, 0xfd987193);
 375       OP (C, D, A, B, 17, 0xa679438e);
 376       OP (B, C, D, A, 22, 0x49b40821);
 377
 378       /* For the second to fourth round we have the possibly swapped words
 379          in CORRECT_WORDS.  Redefine the macro to take an additional first
 380          argument specifying the function to use.  */
 381 #undef OP
 382 #define OP(f, a, b, c, d, k, s, T)                                      \
 383       do                                                                \
 384         {                                                               \
 385           a += f (b, c, d) + correct_words[k] + T;                      \
 386           CYCLIC (a, s);                                                \
 387           a += b;                                                       \
 388         }                                                               \
 389       while (0)
 390
 391       /* Round 2.  */
 392       OP (FG, A, B, C, D,  1,  5, 0xf61e2562);
 393       OP (FG, D, A, B, C,  6,  9, 0xc040b340);
 394       OP (FG, C, D, A, B, 11, 14, 0x265e5a51);
 395       OP (FG, B, C, D, A,  0, 20, 0xe9b6c7aa);
 396       OP (FG, A, B, C, D,  5,  5, 0xd62f105d);
 397       OP (FG, D, A, B, C, 10,  9, 0x02441453);
 398       OP (FG, C, D, A, B, 15, 14, 0xd8a1e681);
 399       OP (FG, B, C, D, A,  4, 20, 0xe7d3fbc8);
 400       OP (FG, A, B, C, D,  9,  5, 0x21e1cde6);
 401       OP (FG, D, A, B, C, 14,  9, 0xc33707d6);
 402       OP (FG, C, D, A, B,  3, 14, 0xf4d50d87);
 403       OP (FG, B, C, D, A,  8, 20, 0x455a14ed);
 404       OP (FG, A, B, C, D, 13,  5, 0xa9e3e905);
 405       OP (FG, D, A, B, C,  2,  9, 0xfcefa3f8);
 406       OP (FG, C, D, A, B,  7, 14, 0x676f02d9);
 407       OP (FG, B, C, D, A, 12, 20, 0x8d2a4c8a);
 408
 409       /* Round 3.  */
 410       OP (FH, A, B, C, D,  5,  4, 0xfffa3942);
 411       OP (FH, D, A, B, C,  8, 11, 0x8771f681);
 412       OP (FH, C, D, A, B, 11, 16, 0x6d9d6122);
 413       OP (FH, B, C, D, A, 14, 23, 0xfde5380c);
 414       OP (FH, A, B, C, D,  1,  4, 0xa4beea44);
 415       OP (FH, D, A, B, C,  4, 11, 0x4bdecfa9);
 416       OP (FH, C, D, A, B,  7, 16, 0xf6bb4b60);
 417       OP (FH, B, C, D, A, 10, 23, 0xbebfbc70);
 418       OP (FH, A, B, C, D, 13,  4, 0x289b7ec6);
 419       OP (FH, D, A, B, C,  0, 11, 0xeaa127fa);
 420       OP (FH, C, D, A, B,  3, 16, 0xd4ef3085);
 421       OP (FH, B, C, D, A,  6, 23, 0x04881d05);
 422       OP (FH, A, B, C, D,  9,  4, 0xd9d4d039);
 423       OP (FH, D, A, B, C, 12, 11, 0xe6db99e5);
 424       OP (FH, C, D, A, B, 15, 16, 0x1fa27cf8);
 425       OP (FH, B, C, D, A,  2, 23, 0xc4ac5665);
 426
 427       /* Round 4.  */
 428       OP (FI, A, B, C, D,  0,  6, 0xf4292244);
 429       OP (FI, D, A, B, C,  7, 10, 0x432aff97);
 430       OP (FI, C, D, A, B, 14, 15, 0xab9423a7);
 431       OP (FI, B, C, D, A,  5, 21, 0xfc93a039);
 432       OP (FI, A, B, C, D, 12,  6, 0x655b59c3);
 433       OP (FI, D, A, B, C,  3, 10, 0x8f0ccc92);
 434       OP (FI, C, D, A, B, 10, 15, 0xffeff47d);
 435       OP (FI, B, C, D, A,  1, 21, 0x85845dd1);
 436       OP (FI, A, B, C, D,  8,  6, 0x6fa87e4f);
 437       OP (FI, D, A, B, C, 15, 10, 0xfe2ce6e0);
 438       OP (FI, C, D, A, B,  6, 15, 0xa3014314);
 439       OP (FI, B, C, D, A, 13, 21, 0x4e0811a1);
 440       OP (FI, A, B, C, D,  4,  6, 0xf7537e82);
 441       OP (FI, D, A, B, C, 11, 10, 0xbd3af235);
 442       OP (FI, C, D, A, B,  2, 15, 0x2ad7d2bb);
 443       OP (FI, B, C, D, A,  9, 21, 0xeb86d391);
 444
 445       /* Add the starting values of the context.  */
 446       A += A_save;
 447       B += B_save;
 448       C += C_save;
 449       D += D_save;
 450     }
 451
 452   /* Put checksum in context given as argument.  */
 453   ctx->A = A;
 454   ctx->B = B;
 455   ctx->C = C;
 456   ctx->D = D;
 457 }