md5-crypt/md5.c

   1 /* md5.c - 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 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 Library General Public License as
   8    published by the Free Software Foundation; either version 2 of the
   9    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    Library General Public License for more details.
  15
  16    You should have received a copy of the GNU Library General Public
  17    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  18    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 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 __ and use weak aliases.  */
  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 (left_over + add > 64)
 231         {
 232           md5_process_block (ctx->buffer, (left_over + add) & ~63, ctx);
 233           /* The regions in the following copy operation cannot overlap.  */
 234           memcpy (ctx->buffer, &ctx->buffer[(left_over + add) & ~63],
 235                   (left_over + add) & 63);
 236           ctx->buflen = (left_over + add) & 63;
 237         }
 238
 239       buffer = (const char *) buffer + add;
 240       len -= add;
 241     }
 242
 243   /* Process available complete blocks.  */
 244   if (len > 64)
 245     {
 246       md5_process_block (buffer, len & ~63, ctx);
 247       buffer = (const char *) buffer + (len & ~63);
 248       len &= 63;
 249     }
 250
 251   /* Move remaining bytes in internal buffer.  */
 252   if (len > 0)
 253     {
 254       memcpy (ctx->buffer, buffer, len);
 255       ctx->buflen = len;
 256     }
 257 }
 258
 259
 260 /* These are the four functions used in the four steps of the MD5 algorithm
 261    and defined in the RFC 1321.  The first function is a little bit optimized
 262    (as found in Colin Plumbs public domain implementation).  */
 263 /* #define FF(b, c, d) ((b & c) | (~b & d)) */
 264 #define FF(b, c, d) (d ^ (b & (c ^ d)))
 265 #define FG(b, c, d) FF (d, b, c)
 266 #define FH(b, c, d) (b ^ c ^ d)
 267 #define FI(b, c, d) (c ^ (b | ~d))
 268
 269 /* Process LEN bytes of BUFFER, accumulating context into CTX.
 270    It is assumed that LEN % 64 == 0.  */
 271
 272 void
 273 md5_process_block (buffer, len, ctx)
 274      const void *buffer;
 275      size_t len;
 276      struct md5_ctx *ctx;
 277 {
 278   md5_uint32 correct_words[16];
 279   const md5_uint32 *words = buffer;
 280   size_t nwords = len / sizeof (md5_uint32);
 281   const md5_uint32 *endp = words + nwords;
 282   md5_uint32 A = ctx->A;
 283   md5_uint32 B = ctx->B;
 284   md5_uint32 C = ctx->C;
 285   md5_uint32 D = ctx->D;
 286
 287   /* First increment the byte count.  RFC 1321 specifies the possible
 288      length of the file up to 2^64 bits.  Here we only compute the
 289      number of bytes.  Do a double word increment.  */
 290   ctx->total[0] += len;
 291   if (ctx->total[0] < len)
 292     ++ctx->total[1];
 293
 294   /* Process all bytes in the buffer with 64 bytes in each round of
 295      the loop.  */
 296   while (words < endp)
 297     {
 298       md5_uint32 *cwp = correct_words;
 299       md5_uint32 A_save = A;
 300       md5_uint32 B_save = B;
 301       md5_uint32 C_save = C;
 302       md5_uint32 D_save = D;
 303
 304       /* First round: using the given function, the context and a constant
 305          the next context is computed.  Because the algorithms processing
 306          unit is a 32-bit word and it is determined to work on words in
 307          little endian byte order we perhaps have to change the byte order
 308          before the computation.  To reduce the work for the next steps
 309          we store the swapped words in the array CORRECT_WORDS.  */
 310
 311 #define OP(a, b, c, d, s, T)                                            \
 312       do                                                                \
 313         {                                                               \
 314           a += FF (b, c, d) + (*cwp++ = SWAP (*words)) + T;             \
 315           ++words;                                                      \
 316           CYCLIC (a, s);                                                \
 317           a += b;                                                       \
 318         }                                                               \
 319       while (0)
 320
 321       /* It is unfortunate that C does not provide an operator for
 322          cyclic rotation.  Hope the C compiler is smart enough.  */
 323 #define CYCLIC(w, s) (w = (w << s) | (w >> (32 - s)))
 324
 325       /* Before we start, one word to the strange constants.
 326          They are defined in RFC 1321 as
 327
 328          T[i] = (int) (4294967296.0 * fabs (sin (i))), i=1..64
 329        */
 330
 331       /* Round 1.  */
 332       OP (A, B, C, D,  7, 0xd76aa478);
 333       OP (D, A, B, C, 12, 0xe8c7b756);
 334       OP (C, D, A, B, 17, 0x242070db);
 335       OP (B, C, D, A, 22, 0xc1bdceee);
 336       OP (A, B, C, D,  7, 0xf57c0faf);
 337       OP (D, A, B, C, 12, 0x4787c62a);
 338       OP (C, D, A, B, 17, 0xa8304613);
 339       OP (B, C, D, A, 22, 0xfd469501);
 340       OP (A, B, C, D,  7, 0x698098d8);
 341       OP (D, A, B, C, 12, 0x8b44f7af);
 342       OP (C, D, A, B, 17, 0xffff5bb1);
 343       OP (B, C, D, A, 22, 0x895cd7be);
 344       OP (A, B, C, D,  7, 0x6b901122);
 345       OP (D, A, B, C, 12, 0xfd987193);
 346       OP (C, D, A, B, 17, 0xa679438e);
 347       OP (B, C, D, A, 22, 0x49b40821);
 348
 349       /* For the second to fourth round we have the possibly swapped words
 350          in CORRECT_WORDS.  Redefine the macro to take an additional first
 351          argument specifying the function to use.  */
 352 #undef OP
 353 #define OP(f, a, b, c, d, k, s, T)                                      \
 354       do                                                                \
 355         {                                                               \
 356           a += f (b, c, d) + correct_words[k] + T;                      \
 357           CYCLIC (a, s);                                                \
 358           a += b;                                                       \
 359         }                                                               \
 360       while (0)
 361
 362       /* Round 2.  */
 363       OP (FG, A, B, C, D,  1,  5, 0xf61e2562);
 364       OP (FG, D, A, B, C,  6,  9, 0xc040b340);
 365       OP (FG, C, D, A, B, 11, 14, 0x265e5a51);
 366       OP (FG, B, C, D, A,  0, 20, 0xe9b6c7aa);
 367       OP (FG, A, B, C, D,  5,  5, 0xd62f105d);
 368       OP (FG, D, A, B, C, 10,  9, 0x02441453);
 369       OP (FG, C, D, A, B, 15, 14, 0xd8a1e681);
 370       OP (FG, B, C, D, A,  4, 20, 0xe7d3fbc8);
 371       OP (FG, A, B, C, D,  9,  5, 0x21e1cde6);
 372       OP (FG, D, A, B, C, 14,  9, 0xc33707d6);
 373       OP (FG, C, D, A, B,  3, 14, 0xf4d50d87);
 374       OP (FG, B, C, D, A,  8, 20, 0x455a14ed);
 375       OP (FG, A, B, C, D, 13,  5, 0xa9e3e905);
 376       OP (FG, D, A, B, C,  2,  9, 0xfcefa3f8);
 377       OP (FG, C, D, A, B,  7, 14, 0x676f02d9);
 378       OP (FG, B, C, D, A, 12, 20, 0x8d2a4c8a);
 379
 380       /* Round 3.  */
 381       OP (FH, A, B, C, D,  5,  4, 0xfffa3942);
 382       OP (FH, D, A, B, C,  8, 11, 0x8771f681);
 383       OP (FH, C, D, A, B, 11, 16, 0x6d9d6122);
 384       OP (FH, B, C, D, A, 14, 23, 0xfde5380c);
 385       OP (FH, A, B, C, D,  1,  4, 0xa4beea44);
 386       OP (FH, D, A, B, C,  4, 11, 0x4bdecfa9);
 387       OP (FH, C, D, A, B,  7, 16, 0xf6bb4b60);
 388       OP (FH, B, C, D, A, 10, 23, 0xbebfbc70);
 389       OP (FH, A, B, C, D, 13,  4, 0x289b7ec6);
 390       OP (FH, D, A, B, C,  0, 11, 0xeaa127fa);
 391       OP (FH, C, D, A, B,  3, 16, 0xd4ef3085);
 392       OP (FH, B, C, D, A,  6, 23, 0x04881d05);
 393       OP (FH, A, B, C, D,  9,  4, 0xd9d4d039);
 394       OP (FH, D, A, B, C, 12, 11, 0xe6db99e5);
 395       OP (FH, C, D, A, B, 15, 16, 0x1fa27cf8);
 396       OP (FH, B, C, D, A,  2, 23, 0xc4ac5665);
 397
 398       /* Round 4.  */
 399       OP (FI, A, B, C, D,  0,  6, 0xf4292244);
 400       OP (FI, D, A, B, C,  7, 10, 0x432aff97);
 401       OP (FI, C, D, A, B, 14, 15, 0xab9423a7);
 402       OP (FI, B, C, D, A,  5, 21, 0xfc93a039);
 403       OP (FI, A, B, C, D, 12,  6, 0x655b59c3);
 404       OP (FI, D, A, B, C,  3, 10, 0x8f0ccc92);
 405       OP (FI, C, D, A, B, 10, 15, 0xffeff47d);
 406       OP (FI, B, C, D, A,  1, 21, 0x85845dd1);
 407       OP (FI, A, B, C, D,  8,  6, 0x6fa87e4f);
 408       OP (FI, D, A, B, C, 15, 10, 0xfe2ce6e0);
 409       OP (FI, C, D, A, B,  6, 15, 0xa3014314);
 410       OP (FI, B, C, D, A, 13, 21, 0x4e0811a1);
 411       OP (FI, A, B, C, D,  4,  6, 0xf7537e82);
 412       OP (FI, D, A, B, C, 11, 10, 0xbd3af235);
 413       OP (FI, C, D, A, B,  2, 15, 0x2ad7d2bb);
 414       OP (FI, B, C, D, A,  9, 21, 0xeb86d391);
 415
 416       /* Add the starting values of the context.  */
 417       A += A_save;
 418       B += B_save;
 419       C += C_save;
 420       D += D_save;
 421     }
 422
 423   /* Put checksum in context given as argument.  */
 424   ctx->A = A;
 425   ctx->B = B;
 426   ctx->C = C;
 427   ctx->D = D;
 428 }
 429
 430
 431 #ifdef _LIBC
 432 /* Define weak aliases.  */
 433 # undef md5_init_ctx
 434 weak_alias (__md5_init_ctx, md5_init_ctx)
 435 # undef md5_process_block
 436 weak_alias (__md5_process_block, md5_process_block)
 437 # undef md5_process_bytes
 438 weak_alias (__md5_process_bytes, md5_process_bytes)
 439 # undef md5_finish_ctx
 440 weak_alias (__md5_finish_ctx, md5_finish_ctx)
 441 # undef md5_read_ctx
 442 weak_alias (__md5_read_ctx, md5_read_ctx)
 443 # undef md5_stream
 444 weak_alias (__md5_stream, md5_stream)
 445 # undef md5_buffer
 446 weak_alias (__md5_buffer, md5_buffer)
 447 #endif