libdvdread4/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 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., 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 <sys/types.h>
  24
  25 #include <stdlib.h>
  26 #include <string.h>
  27
  28 #include "md5.h"
  29 /* #include "unlocked-io.h" */
  30
  31 #ifdef _LIBC
  32 # include <endian.h>
  33 # if __BYTE_ORDER == __BIG_ENDIAN
  34 #  define WORDS_BIGENDIAN 1
  35 # endif
  36 #endif
  37
  38 #ifdef WORDS_BIGENDIAN
  39 # define SWAP(n)                                                        \
  40   (((n) << 24) | (((n) & 0xff00) << 8) | (((n) >> 8) & 0xff00) | ((n) >> 24))
  41 #else
  42 # define SWAP(n) (n)
  43 #endif
  44
  45
  46 /* This array contains the bytes used to pad the buffer to the next
  47    64-byte boundary.  (RFC 1321, 3.1: Step 1)  */
  48 static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ...  */ };
  49
  50
  51 /* Initialize structure containing state of computation.
  52    (RFC 1321, 3.3: Step 3)  */
  53 void
  54 md5_init_ctx (ctx)
  55      struct md5_ctx *ctx;
  56 {
  57   ctx->A = 0x67452301;
  58   ctx->B = 0xefcdab89;
  59   ctx->C = 0x98badcfe;
  60   ctx->D = 0x10325476;
  61
  62   ctx->total[0] = ctx->total[1] = 0;
  63   ctx->buflen = 0;
  64 }
  65
  66 /* Put result from CTX in first 16 bytes following RESBUF.  The result
  67    must be in little endian byte order.
  68
  69    IMPORTANT: On some systems it is required that RESBUF is correctly
  70    aligned for a 32 bits value.  */
  71 void *
  72 md5_read_ctx (ctx, resbuf)
  73      const struct md5_ctx *ctx;
  74      void *resbuf;
  75 {
  76   ((md5_uint32 *) resbuf)[0] = SWAP (ctx->A);
  77   ((md5_uint32 *) resbuf)[1] = SWAP (ctx->B);
  78   ((md5_uint32 *) resbuf)[2] = SWAP (ctx->C);
  79   ((md5_uint32 *) resbuf)[3] = SWAP (ctx->D);
  80
  81   return resbuf;
  82 }
  83
  84 /* Process the remaining bytes in the internal buffer and the usual
  85    prolog according to the standard and write the result to RESBUF.
  86
  87    IMPORTANT: On some systems it is required that RESBUF is correctly
  88    aligned for a 32 bits value.  */
  89 void *
  90 md5_finish_ctx (ctx, resbuf)
  91      struct md5_ctx *ctx;
  92      void *resbuf;
  93 {
  94   /* Take yet unprocessed bytes into account.  */
  95   md5_uint32 bytes = ctx->buflen;
  96   size_t pad;
  97
  98   /* Now count remaining bytes.  */
  99   ctx->total[0] += bytes;
 100   if (ctx->total[0] < bytes)
 101     ++ctx->total[1];
 102
 103   pad = bytes >= 56 ? 64 + 56 - bytes : 56 - bytes;
 104   memcpy (&ctx->buffer[bytes], fillbuf, pad);
 105
 106   /* Put the 64-bit file length in *bits* at the end of the buffer.  */
 107   *(md5_uint32 *) &ctx->buffer[bytes + pad] = SWAP (ctx->total[0] << 3);
 108   *(md5_uint32 *) &ctx->buffer[bytes + pad + 4] = SWAP ((ctx->total[1] << 3) |
 109                                                         (ctx->total[0] >> 29));
 110
 111   /* Process last bytes.  */
 112   md5_process_block (ctx->buffer, bytes + pad + 8, ctx);
 113
 114   return md5_read_ctx (ctx, resbuf);
 115 }
 116
 117 /* Compute MD5 message digest for bytes read from STREAM.  The
 118    resulting message digest number will be written into the 16 bytes
 119    beginning at RESBLOCK.  */
 120 int
 121 md5_stream (stream, resblock)
 122      FILE *stream;
 123      void *resblock;
 124 {
 125   /* Important: BLOCKSIZE must be a multiple of 64.  */
 126 #define BLOCKSIZE 4096
 127   struct md5_ctx ctx;
 128   char buffer[BLOCKSIZE + 72];
 129   size_t sum;
 130
 131   /* Initialize the computation context.  */
 132   md5_init_ctx (&ctx);
 133
 134   /* Iterate over full file contents.  */
 135   while (1)
 136     {
 137       /* We read the file in blocks of BLOCKSIZE bytes.  One call of the
 138          computation function processes the whole buffer so that with the
 139          next round of the loop another block can be read.  */
 140       size_t n;
 141       sum = 0;
 142
 143       /* Read block.  Take care for partial reads.  */
 144       do
 145         {
 146           n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);
 147
 148           sum += n;
 149         }
 150       while (sum < BLOCKSIZE && n != 0);
 151       if (n == 0 && ferror (stream))
 152         return 1;
 153
 154       /* If end of file is reached, end the loop.  */
 155       if (n == 0)
 156         break;
 157
 158       /* Process buffer with BLOCKSIZE bytes.  Note that
 159          BLOCKSIZE % 64 == 0
 160        */
 161       md5_process_block (buffer, BLOCKSIZE, &ctx);
 162     }
 163
 164   /* Add the last bytes if necessary.  */
 165   if (sum > 0)
 166     md5_process_bytes (buffer, sum, &ctx);
 167
 168   /* Construct result in desired memory.  */
 169   md5_finish_ctx (&ctx, resblock);
 170   return 0;
 171 }
 172
 173 /* Compute MD5 message digest for LEN bytes beginning at BUFFER.  The
 174    result is always in little endian byte order, so that a byte-wise
 175    output yields to the wanted ASCII representation of the message
 176    digest.  */
 177 void *
 178 md5_buffer (buffer, len, resblock)
 179      const char *buffer;
 180      size_t len;
 181      void *resblock;
 182 {
 183   struct md5_ctx ctx;
 184
 185   /* Initialize the computation context.  */
 186   md5_init_ctx (&ctx);
 187
 188   /* Process whole buffer but last len % 64 bytes.  */
 189   md5_process_bytes (buffer, len, &ctx);
 190
 191   /* Put result in desired memory area.  */
 192   return md5_finish_ctx (&ctx, resblock);
 193 }
 194
 195
 196 void
 197 md5_process_bytes (buffer, len, ctx)
 198      const void *buffer;
 199      size_t len;
 200      struct md5_ctx *ctx;
 201 {
 202   /* When we already have some bits in our internal buffer concatenate
 203      both inputs first.  */
 204   if (ctx->buflen != 0)
 205     {
 206       size_t left_over = ctx->buflen;
 207       size_t add = 128 - left_over > len ? len : 128 - left_over;
 208
 209       memcpy (&ctx->buffer[left_over], buffer, add);
 210       ctx->buflen += add;
 211
 212       if (left_over + add > 64)
 213         {
 214           md5_process_block (ctx->buffer, (left_over + add) & ~63, ctx);
 215           /* The regions in the following copy operation cannot overlap.  */
 216           memcpy (ctx->buffer, &ctx->buffer[(left_over + add) & ~63],
 217                   (left_over + add) & 63);
 218           ctx->buflen = (left_over + add) & 63;
 219         }
 220
 221       buffer = (const char *) buffer + add;
 222       len -= add;
 223     }
 224
 225   /* Process available complete blocks.  */
 226   if (len > 64)
 227     {
 228       md5_process_block (buffer, len & ~63, ctx);
 229       buffer = (const char *) buffer + (len & ~63);
 230       len &= 63;
 231     }
 232
 233   /* Move remaining bytes in internal buffer.  */
 234   if (len > 0)
 235     {
 236       memcpy (ctx->buffer, buffer, len);
 237       ctx->buflen = len;
 238     }
 239 }
 240
 241
 242 /* These are the four functions used in the four steps of the MD5 algorithm
 243    and defined in the RFC 1321.  The first function is a little bit optimized
 244    (as found in Colin Plumbs public domain implementation).  */
 245 /* #define FF(b, c, d) ((b & c) | (~b & d)) */
 246 #define FF(b, c, d) (d ^ (b & (c ^ d)))
 247 #define FG(b, c, d) FF (d, b, c)
 248 #define FH(b, c, d) (b ^ c ^ d)
 249 #define FI(b, c, d) (c ^ (b | ~d))
 250
 251 /* Process LEN bytes of BUFFER, accumulating context into CTX.
 252    It is assumed that LEN % 64 == 0.  */
 253
 254 void
 255 md5_process_block (buffer, len, ctx)
 256      const void *buffer;
 257      size_t len;
 258      struct md5_ctx *ctx;
 259 {
 260   md5_uint32 correct_words[16];
 261   const md5_uint32 *words = buffer;
 262   size_t nwords = len / sizeof (md5_uint32);
 263   const md5_uint32 *endp = words + nwords;
 264   md5_uint32 A = ctx->A;
 265   md5_uint32 B = ctx->B;
 266   md5_uint32 C = ctx->C;
 267   md5_uint32 D = ctx->D;
 268
 269   /* First increment the byte count.  RFC 1321 specifies the possible
 270      length of the file up to 2^64 bits.  Here we only compute the
 271      number of bytes.  Do a double word increment.  */
 272   ctx->total[0] += len;
 273   if (ctx->total[0] < len)
 274     ++ctx->total[1];
 275
 276   /* Process all bytes in the buffer with 64 bytes in each round of
 277      the loop.  */
 278   while (words < endp)
 279     {
 280       md5_uint32 *cwp = correct_words;
 281       md5_uint32 A_save = A;
 282       md5_uint32 B_save = B;
 283       md5_uint32 C_save = C;
 284       md5_uint32 D_save = D;
 285
 286       /* First round: using the given function, the context and a constant
 287          the next context is computed.  Because the algorithms processing
 288          unit is a 32-bit word and it is determined to work on words in
 289          little endian byte order we perhaps have to change the byte order
 290          before the computation.  To reduce the work for the next steps
 291          we store the swapped words in the array CORRECT_WORDS.  */
 292
 293 #define OP(a, b, c, d, s, T)                                    \
 294       do                                                        \
 295         {                                                       \
 296           a += FF (b, c, d) + (*cwp++ = SWAP (*words)) + T;     \
 297           ++words;                                              \
 298           a = rol (a, s);                                       \
 299           a += b;                                               \
 300         }                                                       \
 301       while (0)
 302
 303       /* Before we start, one word to the strange constants.
 304          They are defined in RFC 1321 as
 305
 306          T[i] = (int) (4294967296.0 * fabs (sin (i))), i=1..64, or
 307          perl -e 'foreach(1..64){printf "0x%08x\n", int (4294967296 * abs (sin $_))}'
 308        */
 309
 310       /* Round 1.  */
 311       OP (A, B, C, D,  7, 0xd76aa478);
 312       OP (D, A, B, C, 12, 0xe8c7b756);
 313       OP (C, D, A, B, 17, 0x242070db);
 314       OP (B, C, D, A, 22, 0xc1bdceee);
 315       OP (A, B, C, D,  7, 0xf57c0faf);
 316       OP (D, A, B, C, 12, 0x4787c62a);
 317       OP (C, D, A, B, 17, 0xa8304613);
 318       OP (B, C, D, A, 22, 0xfd469501);
 319       OP (A, B, C, D,  7, 0x698098d8);
 320       OP (D, A, B, C, 12, 0x8b44f7af);
 321       OP (C, D, A, B, 17, 0xffff5bb1);
 322       OP (B, C, D, A, 22, 0x895cd7be);
 323       OP (A, B, C, D,  7, 0x6b901122);
 324       OP (D, A, B, C, 12, 0xfd987193);
 325       OP (C, D, A, B, 17, 0xa679438e);
 326       OP (B, C, D, A, 22, 0x49b40821);
 327
 328       /* For the second to fourth round we have the possibly swapped words
 329          in CORRECT_WORDS.  Redefine the macro to take an additional first
 330          argument specifying the function to use.  */
 331 #undef OP
 332 #define OP(f, a, b, c, d, k, s, T)                      \
 333       do                                                \
 334         {                                               \
 335           a += f (b, c, d) + correct_words[k] + T;      \
 336           a = rol (a, s);                               \
 337           a += b;                                       \
 338         }                                               \
 339       while (0)
 340
 341       /* Round 2.  */
 342       OP (FG, A, B, C, D,  1,  5, 0xf61e2562);
 343       OP (FG, D, A, B, C,  6,  9, 0xc040b340);
 344       OP (FG, C, D, A, B, 11, 14, 0x265e5a51);
 345       OP (FG, B, C, D, A,  0, 20, 0xe9b6c7aa);
 346       OP (FG, A, B, C, D,  5,  5, 0xd62f105d);
 347       OP (FG, D, A, B, C, 10,  9, 0x02441453);
 348       OP (FG, C, D, A, B, 15, 14, 0xd8a1e681);
 349       OP (FG, B, C, D, A,  4, 20, 0xe7d3fbc8);
 350       OP (FG, A, B, C, D,  9,  5, 0x21e1cde6);
 351       OP (FG, D, A, B, C, 14,  9, 0xc33707d6);
 352       OP (FG, C, D, A, B,  3, 14, 0xf4d50d87);
 353       OP (FG, B, C, D, A,  8, 20, 0x455a14ed);
 354       OP (FG, A, B, C, D, 13,  5, 0xa9e3e905);
 355       OP (FG, D, A, B, C,  2,  9, 0xfcefa3f8);
 356       OP (FG, C, D, A, B,  7, 14, 0x676f02d9);
 357       OP (FG, B, C, D, A, 12, 20, 0x8d2a4c8a);
 358
 359       /* Round 3.  */
 360       OP (FH, A, B, C, D,  5,  4, 0xfffa3942);
 361       OP (FH, D, A, B, C,  8, 11, 0x8771f681);
 362       OP (FH, C, D, A, B, 11, 16, 0x6d9d6122);
 363       OP (FH, B, C, D, A, 14, 23, 0xfde5380c);
 364       OP (FH, A, B, C, D,  1,  4, 0xa4beea44);
 365       OP (FH, D, A, B, C,  4, 11, 0x4bdecfa9);
 366       OP (FH, C, D, A, B,  7, 16, 0xf6bb4b60);
 367       OP (FH, B, C, D, A, 10, 23, 0xbebfbc70);
 368       OP (FH, A, B, C, D, 13,  4, 0x289b7ec6);
 369       OP (FH, D, A, B, C,  0, 11, 0xeaa127fa);
 370       OP (FH, C, D, A, B,  3, 16, 0xd4ef3085);
 371       OP (FH, B, C, D, A,  6, 23, 0x04881d05);
 372       OP (FH, A, B, C, D,  9,  4, 0xd9d4d039);
 373       OP (FH, D, A, B, C, 12, 11, 0xe6db99e5);
 374       OP (FH, C, D, A, B, 15, 16, 0x1fa27cf8);
 375       OP (FH, B, C, D, A,  2, 23, 0xc4ac5665);
 376
 377       /* Round 4.  */
 378       OP (FI, A, B, C, D,  0,  6, 0xf4292244);
 379       OP (FI, D, A, B, C,  7, 10, 0x432aff97);
 380       OP (FI, C, D, A, B, 14, 15, 0xab9423a7);
 381       OP (FI, B, C, D, A,  5, 21, 0xfc93a039);
 382       OP (FI, A, B, C, D, 12,  6, 0x655b59c3);
 383       OP (FI, D, A, B, C,  3, 10, 0x8f0ccc92);
 384       OP (FI, C, D, A, B, 10, 15, 0xffeff47d);
 385       OP (FI, B, C, D, A,  1, 21, 0x85845dd1);
 386       OP (FI, A, B, C, D,  8,  6, 0x6fa87e4f);
 387       OP (FI, D, A, B, C, 15, 10, 0xfe2ce6e0);
 388       OP (FI, C, D, A, B,  6, 15, 0xa3014314);
 389       OP (FI, B, C, D, A, 13, 21, 0x4e0811a1);
 390       OP (FI, A, B, C, D,  4,  6, 0xf7537e82);
 391       OP (FI, D, A, B, C, 11, 10, 0xbd3af235);
 392       OP (FI, C, D, A, B,  2, 15, 0x2ad7d2bb);
 393       OP (FI, B, C, D, A,  9, 21, 0xeb86d391);
 394
 395       /* Add the starting values of the context.  */
 396       A += A_save;
 397       B += B_save;
 398       C += C_save;
 399       D += D_save;
 400     }
 401
 402   /* Put checksum in context given as argument.  */
 403   ctx->A = A;
 404   ctx->B = B;
 405   ctx->C = C;
 406   ctx->D = D;
 407 }