lib/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, 2001, 2003, 2004 Free Software Foundation, Inc.
   4    NOTE: The canonical source of this file is maintained with the GNU C
   5    Library.  Bugs can be reported to bug-glibc@prep.ai.mit.edu.
   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 2, 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., 59 Temple Place - Suite 330, 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 "md5.h"
  28
  29 #include <stddef.h>
  30 #include <string.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 4096
  60 /* Ensure that BLOCKSIZE is a multiple of 64.  */
  61 #if BLOCKSIZE % 64 != 0
  62 /* FIXME-someday (soon?): use #error instead of this kludge.  */
  63 "invalid BLOCKSIZE"
  64 #endif
  65
  66 /* This array contains the bytes used to pad the buffer to the next
  67    64-byte boundary.  (RFC 1321, 3.1: Step 1)  */
  68 static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ...  */ };
  69
  70
  71 /* Initialize structure containing state of computation.
  72    (RFC 1321, 3.3: Step 3)  */
  73 void
  74 md5_init_ctx (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 (const struct md5_ctx *ctx, void *resbuf)
  92 {
  93   ((md5_uint32 *) resbuf)[0] = SWAP (ctx->A);
  94   ((md5_uint32 *) resbuf)[1] = SWAP (ctx->B);
  95   ((md5_uint32 *) resbuf)[2] = SWAP (ctx->C);
  96   ((md5_uint32 *) resbuf)[3] = SWAP (ctx->D);
  97
  98   return resbuf;
  99 }
 100
 101 /* Process the remaining bytes in the internal buffer and the usual
 102    prolog according to the standard and write the result to RESBUF.
 103
 104    IMPORTANT: On some systems it is required that RESBUF is correctly
 105    aligned for a 32 bits value.  */
 106 void *
 107 md5_finish_ctx (struct md5_ctx *ctx, void *resbuf)
 108 {
 109   /* Take yet unprocessed bytes into account.  */
 110   md5_uint32 bytes = ctx->buflen;
 111   size_t pad;
 112
 113   /* Now count remaining bytes.  */
 114   ctx->total[0] += bytes;
 115   if (ctx->total[0] < bytes)
 116     ++ctx->total[1];
 117
 118   pad = bytes >= 56 ? 64 + 56 - bytes : 56 - bytes;
 119   memcpy (&ctx->buffer[bytes], fillbuf, pad);
 120
 121   /* Put the 64-bit file length in *bits* at the end of the buffer.  */
 122   *(md5_uint32 *) &ctx->buffer[bytes + pad] = SWAP (ctx->total[0] << 3);
 123   *(md5_uint32 *) &ctx->buffer[bytes + pad + 4] = SWAP ((ctx->total[1] << 3) |
 124                                                         (ctx->total[0] >> 29));
 125
 126   /* Process last bytes.  */
 127   md5_process_block (ctx->buffer, bytes + pad + 8, 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   char buffer[BLOCKSIZE + 72];
 140   size_t sum;
 141
 142   /* Initialize the computation context.  */
 143   md5_init_ctx (&ctx);
 144
 145   /* Iterate over full file contents.  */
 146   while (1)
 147     {
 148       /* We read the file in blocks of BLOCKSIZE bytes.  One call of the
 149          computation function processes the whole buffer so that with the
 150          next round of the loop another block can be read.  */
 151       size_t n;
 152       sum = 0;
 153
 154       /* Read block.  Take care for partial reads.  */
 155       while (1)
 156         {
 157           n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);
 158
 159           sum += n;
 160
 161           if (sum == BLOCKSIZE)
 162             break;
 163
 164           if (n == 0)
 165             {
 166               /* Check for the error flag IFF N == 0, so that we don't
 167                  exit the loop after a partial read due to e.g., EAGAIN
 168                  or EWOULDBLOCK.  */
 169               if (ferror (stream))
 170                 return 1;
 171               goto process_partial_block;
 172             }
 173
 174           /* We've read at least one byte, so ignore errors.  But always
 175              check for EOF, since feof may be true even though N > 0.
 176              Otherwise, we could end up calling fread after EOF.  */
 177           if (feof (stream))
 178             goto process_partial_block;
 179         }
 180
 181       /* Process buffer with BLOCKSIZE bytes.  Note that
 182                         BLOCKSIZE % 64 == 0
 183        */
 184       md5_process_block (buffer, BLOCKSIZE, &ctx);
 185     }
 186
 187  process_partial_block:;
 188
 189   /* Process any remaining bytes.  */
 190   if (sum > 0)
 191     md5_process_bytes (buffer, sum, &ctx);
 192
 193   /* Construct result in desired memory.  */
 194   md5_finish_ctx (&ctx, resblock);
 195   return 0;
 196 }
 197
 198 /* Compute MD5 message digest for LEN bytes beginning at BUFFER.  The
 199    result is always in little endian byte order, so that a byte-wise
 200    output yields to the wanted ASCII representation of the message
 201    digest.  */
 202 void *
 203 md5_buffer (const char *buffer, size_t len, void *resblock)
 204 {
 205   struct md5_ctx ctx;
 206
 207   /* Initialize the computation context.  */
 208   md5_init_ctx (&ctx);
 209
 210   /* Process whole buffer but last len % 64 bytes.  */
 211   md5_process_bytes (buffer, len, &ctx);
 212
 213   /* Put result in desired memory area.  */
 214   return md5_finish_ctx (&ctx, resblock);
 215 }
 216
 217
 218 void
 219 md5_process_bytes (const void *buffer, size_t len, 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 # define alignof(type) offsetof (struct { char c; type x; }, x)
 250 # define UNALIGNED_P(p) (((size_t) p) % alignof (md5_uint32) != 0)
 251       if (UNALIGNED_P (buffer))
 252         while (len > 64)
 253           {
 254             md5_process_block (memcpy (ctx->buffer, buffer, 64), 64, ctx);
 255             buffer = (const char *) buffer + 64;
 256             len -= 64;
 257           }
 258       else
 259 #endif
 260         {
 261           md5_process_block (buffer, len & ~63, ctx);
 262           buffer = (const char *) buffer + (len & ~63);
 263           len &= 63;
 264         }
 265     }
 266
 267   /* Move remaining bytes in internal buffer.  */
 268   if (len > 0)
 269     {
 270       size_t left_over = ctx->buflen;
 271
 272       memcpy (&ctx->buffer[left_over], buffer, len);
 273       left_over += len;
 274       if (left_over >= 64)
 275         {
 276           md5_process_block (ctx->buffer, 64, ctx);
 277           left_over -= 64;
 278           memcpy (ctx->buffer, &ctx->buffer[64], left_over);
 279         }
 280       ctx->buflen = left_over;
 281     }
 282 }
 283
 284
 285 /* These are the four functions used in the four steps of the MD5 algorithm
 286    and defined in the RFC 1321.  The first function is a little bit optimized
 287    (as found in Colin Plumbs public domain implementation).  */
 288 /* #define FF(b, c, d) ((b & c) | (~b & d)) */
 289 #define FF(b, c, d) (d ^ (b & (c ^ d)))
 290 #define FG(b, c, d) FF (d, b, c)
 291 #define FH(b, c, d) (b ^ c ^ d)
 292 #define FI(b, c, d) (c ^ (b | ~d))
 293
 294 /* Process LEN bytes of BUFFER, accumulating context into CTX.
 295    It is assumed that LEN % 64 == 0.  */
 296
 297 void
 298 md5_process_block (const void *buffer, size_t len, struct md5_ctx *ctx)
 299 {
 300   md5_uint32 correct_words[16];
 301   const md5_uint32 *words = buffer;
 302   size_t nwords = len / sizeof (md5_uint32);
 303   const md5_uint32 *endp = words + nwords;
 304   md5_uint32 A = ctx->A;
 305   md5_uint32 B = ctx->B;
 306   md5_uint32 C = ctx->C;
 307   md5_uint32 D = ctx->D;
 308
 309   /* First increment the byte count.  RFC 1321 specifies the possible
 310      length of the file up to 2^64 bits.  Here we only compute the
 311      number of bytes.  Do a double word increment.  */
 312   ctx->total[0] += len;
 313   if (ctx->total[0] < len)
 314     ++ctx->total[1];
 315
 316   /* Process all bytes in the buffer with 64 bytes in each round of
 317      the loop.  */
 318   while (words < endp)
 319     {
 320       md5_uint32 *cwp = correct_words;
 321       md5_uint32 A_save = A;
 322       md5_uint32 B_save = B;
 323       md5_uint32 C_save = C;
 324       md5_uint32 D_save = D;
 325
 326       /* First round: using the given function, the context and a constant
 327          the next context is computed.  Because the algorithms processing
 328          unit is a 32-bit word and it is determined to work on words in
 329          little endian byte order we perhaps have to change the byte order
 330          before the computation.  To reduce the work for the next steps
 331          we store the swapped words in the array CORRECT_WORDS.  */
 332
 333 #define OP(a, b, c, d, s, T)                                            \
 334       do                                                                \
 335         {                                                               \
 336           a += FF (b, c, d) + (*cwp++ = SWAP (*words)) + T;             \
 337           ++words;                                                      \
 338           a = rol (a, s);                                               \
 339           a += b;                                                       \
 340         }                                                               \
 341       while (0)
 342
 343       /* Before we start, one word to the strange constants.
 344          They are defined in RFC 1321 as
 345
 346          T[i] = (int) (4294967296.0 * fabs (sin (i))), i=1..64, or
 347          perl -e 'foreach(1..64){printf "0x%08x\n", int (4294967296 * abs (sin $_))}'
 348        */
 349
 350       /* Round 1.  */
 351       OP (A, B, C, D,  7, 0xd76aa478);
 352       OP (D, A, B, C, 12, 0xe8c7b756);
 353       OP (C, D, A, B, 17, 0x242070db);
 354       OP (B, C, D, A, 22, 0xc1bdceee);
 355       OP (A, B, C, D,  7, 0xf57c0faf);
 356       OP (D, A, B, C, 12, 0x4787c62a);
 357       OP (C, D, A, B, 17, 0xa8304613);
 358       OP (B, C, D, A, 22, 0xfd469501);
 359       OP (A, B, C, D,  7, 0x698098d8);
 360       OP (D, A, B, C, 12, 0x8b44f7af);
 361       OP (C, D, A, B, 17, 0xffff5bb1);
 362       OP (B, C, D, A, 22, 0x895cd7be);
 363       OP (A, B, C, D,  7, 0x6b901122);
 364       OP (D, A, B, C, 12, 0xfd987193);
 365       OP (C, D, A, B, 17, 0xa679438e);
 366       OP (B, C, D, A, 22, 0x49b40821);
 367
 368       /* For the second to fourth round we have the possibly swapped words
 369          in CORRECT_WORDS.  Redefine the macro to take an additional first
 370          argument specifying the function to use.  */
 371 #undef OP
 372 #define OP(f, a, b, c, d, k, s, T)                                      \
 373       do                                                                \
 374         {                                                               \
 375           a += f (b, c, d) + correct_words[k] + T;                      \
 376           a = rol (a, s);                                               \
 377           a += b;                                                       \
 378         }                                                               \
 379       while (0)
 380
 381       /* Round 2.  */
 382       OP (FG, A, B, C, D,  1,  5, 0xf61e2562);
 383       OP (FG, D, A, B, C,  6,  9, 0xc040b340);
 384       OP (FG, C, D, A, B, 11, 14, 0x265e5a51);
 385       OP (FG, B, C, D, A,  0, 20, 0xe9b6c7aa);
 386       OP (FG, A, B, C, D,  5,  5, 0xd62f105d);
 387       OP (FG, D, A, B, C, 10,  9, 0x02441453);
 388       OP (FG, C, D, A, B, 15, 14, 0xd8a1e681);
 389       OP (FG, B, C, D, A,  4, 20, 0xe7d3fbc8);
 390       OP (FG, A, B, C, D,  9,  5, 0x21e1cde6);
 391       OP (FG, D, A, B, C, 14,  9, 0xc33707d6);
 392       OP (FG, C, D, A, B,  3, 14, 0xf4d50d87);
 393       OP (FG, B, C, D, A,  8, 20, 0x455a14ed);
 394       OP (FG, A, B, C, D, 13,  5, 0xa9e3e905);
 395       OP (FG, D, A, B, C,  2,  9, 0xfcefa3f8);
 396       OP (FG, C, D, A, B,  7, 14, 0x676f02d9);
 397       OP (FG, B, C, D, A, 12, 20, 0x8d2a4c8a);
 398
 399       /* Round 3.  */
 400       OP (FH, A, B, C, D,  5,  4, 0xfffa3942);
 401       OP (FH, D, A, B, C,  8, 11, 0x8771f681);
 402       OP (FH, C, D, A, B, 11, 16, 0x6d9d6122);
 403       OP (FH, B, C, D, A, 14, 23, 0xfde5380c);
 404       OP (FH, A, B, C, D,  1,  4, 0xa4beea44);
 405       OP (FH, D, A, B, C,  4, 11, 0x4bdecfa9);
 406       OP (FH, C, D, A, B,  7, 16, 0xf6bb4b60);
 407       OP (FH, B, C, D, A, 10, 23, 0xbebfbc70);
 408       OP (FH, A, B, C, D, 13,  4, 0x289b7ec6);
 409       OP (FH, D, A, B, C,  0, 11, 0xeaa127fa);
 410       OP (FH, C, D, A, B,  3, 16, 0xd4ef3085);
 411       OP (FH, B, C, D, A,  6, 23, 0x04881d05);
 412       OP (FH, A, B, C, D,  9,  4, 0xd9d4d039);
 413       OP (FH, D, A, B, C, 12, 11, 0xe6db99e5);
 414       OP (FH, C, D, A, B, 15, 16, 0x1fa27cf8);
 415       OP (FH, B, C, D, A,  2, 23, 0xc4ac5665);
 416
 417       /* Round 4.  */
 418       OP (FI, A, B, C, D,  0,  6, 0xf4292244);
 419       OP (FI, D, A, B, C,  7, 10, 0x432aff97);
 420       OP (FI, C, D, A, B, 14, 15, 0xab9423a7);
 421       OP (FI, B, C, D, A,  5, 21, 0xfc93a039);
 422       OP (FI, A, B, C, D, 12,  6, 0x655b59c3);
 423       OP (FI, D, A, B, C,  3, 10, 0x8f0ccc92);
 424       OP (FI, C, D, A, B, 10, 15, 0xffeff47d);
 425       OP (FI, B, C, D, A,  1, 21, 0x85845dd1);
 426       OP (FI, A, B, C, D,  8,  6, 0x6fa87e4f);
 427       OP (FI, D, A, B, C, 15, 10, 0xfe2ce6e0);
 428       OP (FI, C, D, A, B,  6, 15, 0xa3014314);
 429       OP (FI, B, C, D, A, 13, 21, 0x4e0811a1);
 430       OP (FI, A, B, C, D,  4,  6, 0xf7537e82);
 431       OP (FI, D, A, B, C, 11, 10, 0xbd3af235);
 432       OP (FI, C, D, A, B,  2, 15, 0x2ad7d2bb);
 433       OP (FI, B, C, D, A,  9, 21, 0xeb86d391);
 434
 435       /* Add the starting values of the context.  */
 436       A += A_save;
 437       B += B_save;
 438       C += C_save;
 439       D += D_save;
 440     }
 441
 442   /* Put checksum in context given as argument.  */
 443   ctx->A = A;
 444   ctx->B = B;
 445   ctx->C = C;
 446   ctx->D = D;
 447 }