libopkg/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) 1995,1996,1997,1999,2000,2001,2005,2006,2008
   4         Free Software Foundation, Inc.
   5    This file is part of the GNU C Library.
   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 <config.h>
  24
  25 #include "md5.h"
  26
  27 #include <stddef.h>
  28 #include <stdlib.h>
  29 #include <string.h>
  30 #include <sys/types.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 #if BLOCKSIZE % 64 != 0
  61 # error "invalid BLOCKSIZE"
  62 #endif
  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 (struct md5_ctx *ctx)
  73 {
  74   ctx->A = 0x67452301;
  75   ctx->B = 0xefcdab89;
  76   ctx->C = 0x98badcfe;
  77   ctx->D = 0x10325476;
  78
  79   ctx->total[0] = ctx->total[1] = 0;
  80   ctx->buflen = 0;
  81 }
  82
  83 /* Copy the 4 byte value from v into the memory location pointed to by *cp,
  84    If your architecture allows unaligned access this is equivalent to
  85    * (uint32_t *) cp = v  */
  86 static inline void
  87 set_uint32 (char *cp, uint32_t v)
  88 {
  89   memcpy (cp, &v, sizeof v);
  90 }
  91
  92 /* Put result from CTX in first 16 bytes following RESBUF.  The result
  93    must be in little endian byte order.  */
  94 void *
  95 md5_read_ctx (const struct md5_ctx *ctx, void *resbuf)
  96 {
  97   char *r = resbuf;
  98   set_uint32 (r + 0 * sizeof ctx->A, SWAP (ctx->A));
  99   set_uint32 (r + 1 * sizeof ctx->B, SWAP (ctx->B));
 100   set_uint32 (r + 2 * sizeof ctx->C, SWAP (ctx->C));
 101   set_uint32 (r + 3 * sizeof ctx->D, SWAP (ctx->D));
 102
 103   return resbuf;
 104 }
 105
 106 /* Process the remaining bytes in the internal buffer and the usual
 107    prolog according to the standard and write the result to RESBUF.  */
 108 void *
 109 md5_finish_ctx (struct md5_ctx *ctx, void *resbuf)
 110 {
 111   /* Take yet unprocessed bytes into account.  */
 112   uint32_t bytes = ctx->buflen;
 113   size_t size = (bytes < 56) ? 64 / 4 : 64 * 2 / 4;
 114
 115   /* Now count remaining bytes.  */
 116   ctx->total[0] += bytes;
 117   if (ctx->total[0] < bytes)
 118     ++ctx->total[1];
 119
 120   /* Put the 64-bit file length in *bits* at the end of the buffer.  */
 121   ctx->buffer[size - 2] = SWAP (ctx->total[0] << 3);
 122   ctx->buffer[size - 1] = SWAP ((ctx->total[1] << 3) | (ctx->total[0] >> 29));
 123
 124   memcpy (&((char *) ctx->buffer)[bytes], fillbuf, (size - 2) * 4 - bytes);
 125
 126   /* Process last bytes.  */
 127   md5_process_block (ctx->buffer, size * 4, 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 (&((char *) 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,
 238                   &((char *) ctx->buffer)[(left_over + add) & ~63],
 239                   ctx->buflen);
 240         }
 241
 242       buffer = (const char *) buffer + add;
 243       len -= add;
 244     }
 245
 246   /* Process available complete blocks.  */
 247   if (len >= 64)
 248     {
 249 #if !_STRING_ARCH_unaligned
 250 # define alignof(type) offsetof (struct { char c; type x; }, x)
 251 # define UNALIGNED_P(p) (((size_t) p) % alignof (uint32_t) != 0)
 252       if (UNALIGNED_P (buffer))
 253         while (len > 64)
 254           {
 255             md5_process_block (memcpy (ctx->buffer, buffer, 64), 64, ctx);
 256             buffer = (const char *) buffer + 64;
 257             len -= 64;
 258           }
 259       else
 260 #endif
 261         {
 262           md5_process_block (buffer, len & ~63, ctx);
 263           buffer = (const char *) buffer + (len & ~63);
 264           len &= 63;
 265         }
 266     }
 267
 268   /* Move remaining bytes in internal buffer.  */
 269   if (len > 0)
 270     {
 271       size_t left_over = ctx->buflen;
 272
 273       memcpy (&((char *) ctx->buffer)[left_over], buffer, len);
 274       left_over += len;
 275       if (left_over >= 64)
 276         {
 277           md5_process_block (ctx->buffer, 64, ctx);
 278           left_over -= 64;
 279           memcpy (ctx->buffer, &ctx->buffer[16], left_over);
 280         }
 281       ctx->buflen = left_over;
 282     }
 283 }
 284
 285
 286 /* These are the four functions used in the four steps of the MD5 algorithm
 287    and defined in the RFC 1321.  The first function is a little bit optimized
 288    (as found in Colin Plumbs public domain implementation).  */
 289 /* #define FF(b, c, d) ((b & c) | (~b & d)) */
 290 #define FF(b, c, d) (d ^ (b & (c ^ d)))
 291 #define FG(b, c, d) FF (d, b, c)
 292 #define FH(b, c, d) (b ^ c ^ d)
 293 #define FI(b, c, d) (c ^ (b | ~d))
 294
 295 /* Process LEN bytes of BUFFER, accumulating context into CTX.
 296    It is assumed that LEN % 64 == 0.  */
 297
 298 void
 299 md5_process_block (const void *buffer, size_t len, struct md5_ctx *ctx)
 300 {
 301   uint32_t correct_words[16];
 302   const uint32_t *words = buffer;
 303   size_t nwords = len / sizeof (uint32_t);
 304   const uint32_t *endp = words + nwords;
 305   uint32_t A = ctx->A;
 306   uint32_t B = ctx->B;
 307   uint32_t C = ctx->C;
 308   uint32_t D = ctx->D;
 309
 310   /* First increment the byte count.  RFC 1321 specifies the possible
 311      length of the file up to 2^64 bits.  Here we only compute the
 312      number of bytes.  Do a double word increment.  */
 313   ctx->total[0] += len;
 314   if (ctx->total[0] < len)
 315     ++ctx->total[1];
 316
 317   /* Process all bytes in the buffer with 64 bytes in each round of
 318      the loop.  */
 319   while (words < endp)
 320     {
 321       uint32_t *cwp = correct_words;
 322       uint32_t A_save = A;
 323       uint32_t B_save = B;
 324       uint32_t C_save = C;
 325       uint32_t D_save = D;
 326
 327       /* First round: using the given function, the context and a constant
 328          the next context is computed.  Because the algorithms processing
 329          unit is a 32-bit word and it is determined to work on words in
 330          little endian byte order we perhaps have to change the byte order
 331          before the computation.  To reduce the work for the next steps
 332          we store the swapped words in the array CORRECT_WORDS.  */
 333
 334 #define OP(a, b, c, d, s, T)                                            \
 335       do                                                                \
 336         {                                                               \
 337           a += FF (b, c, d) + (*cwp++ = SWAP (*words)) + T;             \
 338           ++words;                                                      \
 339           CYCLIC (a, s);                                                \
 340           a += b;                                                       \
 341         }                                                               \
 342       while (0)
 343
 344       /* It is unfortunate that C does not provide an operator for
 345          cyclic rotation.  Hope the C compiler is smart enough.  */
 346 #define CYCLIC(w, s) (w = (w << s) | (w >> (32 - s)))
 347
 348       /* Before we start, one word to the strange constants.
 349          They are defined in RFC 1321 as
 350
 351          T[i] = (int) (4294967296.0 * fabs (sin (i))), i=1..64
 352
 353          Here is an equivalent invocation using Perl:
 354
 355          perl -e 'foreach(1..64){printf "0x%08x\n", int (4294967296 * abs (sin $_))}'
 356        */
 357
 358       /* Round 1.  */
 359       OP (A, B, C, D, 7, 0xd76aa478);
 360       OP (D, A, B, C, 12, 0xe8c7b756);
 361       OP (C, D, A, B, 17, 0x242070db);
 362       OP (B, C, D, A, 22, 0xc1bdceee);
 363       OP (A, B, C, D, 7, 0xf57c0faf);
 364       OP (D, A, B, C, 12, 0x4787c62a);
 365       OP (C, D, A, B, 17, 0xa8304613);
 366       OP (B, C, D, A, 22, 0xfd469501);
 367       OP (A, B, C, D, 7, 0x698098d8);
 368       OP (D, A, B, C, 12, 0x8b44f7af);
 369       OP (C, D, A, B, 17, 0xffff5bb1);
 370       OP (B, C, D, A, 22, 0x895cd7be);
 371       OP (A, B, C, D, 7, 0x6b901122);
 372       OP (D, A, B, C, 12, 0xfd987193);
 373       OP (C, D, A, B, 17, 0xa679438e);
 374       OP (B, C, D, A, 22, 0x49b40821);
 375
 376       /* For the second to fourth round we have the possibly swapped words
 377          in CORRECT_WORDS.  Redefine the macro to take an additional first
 378          argument specifying the function to use.  */
 379 #undef OP
 380 #define OP(f, a, b, c, d, k, s, T)                                      \
 381       do                                                                \
 382         {                                                               \
 383           a += f (b, c, d) + correct_words[k] + T;                      \
 384           CYCLIC (a, s);                                                \
 385           a += b;                                                       \
 386         }                                                               \
 387       while (0)
 388
 389       /* Round 2.  */
 390       OP (FG, A, B, C, D, 1, 5, 0xf61e2562);
 391       OP (FG, D, A, B, C, 6, 9, 0xc040b340);
 392       OP (FG, C, D, A, B, 11, 14, 0x265e5a51);
 393       OP (FG, B, C, D, A, 0, 20, 0xe9b6c7aa);
 394       OP (FG, A, B, C, D, 5, 5, 0xd62f105d);
 395       OP (FG, D, A, B, C, 10, 9, 0x02441453);
 396       OP (FG, C, D, A, B, 15, 14, 0xd8a1e681);
 397       OP (FG, B, C, D, A, 4, 20, 0xe7d3fbc8);
 398       OP (FG, A, B, C, D, 9, 5, 0x21e1cde6);
 399       OP (FG, D, A, B, C, 14, 9, 0xc33707d6);
 400       OP (FG, C, D, A, B, 3, 14, 0xf4d50d87);
 401       OP (FG, B, C, D, A, 8, 20, 0x455a14ed);
 402       OP (FG, A, B, C, D, 13, 5, 0xa9e3e905);
 403       OP (FG, D, A, B, C, 2, 9, 0xfcefa3f8);
 404       OP (FG, C, D, A, B, 7, 14, 0x676f02d9);
 405       OP (FG, B, C, D, A, 12, 20, 0x8d2a4c8a);
 406
 407       /* Round 3.  */
 408       OP (FH, A, B, C, D, 5, 4, 0xfffa3942);
 409       OP (FH, D, A, B, C, 8, 11, 0x8771f681);
 410       OP (FH, C, D, A, B, 11, 16, 0x6d9d6122);
 411       OP (FH, B, C, D, A, 14, 23, 0xfde5380c);
 412       OP (FH, A, B, C, D, 1, 4, 0xa4beea44);
 413       OP (FH, D, A, B, C, 4, 11, 0x4bdecfa9);
 414       OP (FH, C, D, A, B, 7, 16, 0xf6bb4b60);
 415       OP (FH, B, C, D, A, 10, 23, 0xbebfbc70);
 416       OP (FH, A, B, C, D, 13, 4, 0x289b7ec6);
 417       OP (FH, D, A, B, C, 0, 11, 0xeaa127fa);
 418       OP (FH, C, D, A, B, 3, 16, 0xd4ef3085);
 419       OP (FH, B, C, D, A, 6, 23, 0x04881d05);
 420       OP (FH, A, B, C, D, 9, 4, 0xd9d4d039);
 421       OP (FH, D, A, B, C, 12, 11, 0xe6db99e5);
 422       OP (FH, C, D, A, B, 15, 16, 0x1fa27cf8);
 423       OP (FH, B, C, D, A, 2, 23, 0xc4ac5665);
 424
 425       /* Round 4.  */
 426       OP (FI, A, B, C, D, 0, 6, 0xf4292244);
 427       OP (FI, D, A, B, C, 7, 10, 0x432aff97);
 428       OP (FI, C, D, A, B, 14, 15, 0xab9423a7);
 429       OP (FI, B, C, D, A, 5, 21, 0xfc93a039);
 430       OP (FI, A, B, C, D, 12, 6, 0x655b59c3);
 431       OP (FI, D, A, B, C, 3, 10, 0x8f0ccc92);
 432       OP (FI, C, D, A, B, 10, 15, 0xffeff47d);
 433       OP (FI, B, C, D, A, 1, 21, 0x85845dd1);
 434       OP (FI, A, B, C, D, 8, 6, 0x6fa87e4f);
 435       OP (FI, D, A, B, C, 15, 10, 0xfe2ce6e0);
 436       OP (FI, C, D, A, B, 6, 15, 0xa3014314);
 437       OP (FI, B, C, D, A, 13, 21, 0x4e0811a1);
 438       OP (FI, A, B, C, D, 4, 6, 0xf7537e82);
 439       OP (FI, D, A, B, C, 11, 10, 0xbd3af235);
 440       OP (FI, C, D, A, B, 2, 15, 0x2ad7d2bb);
 441       OP (FI, B, C, D, A, 9, 21, 0xeb86d391);
 442
 443       /* Add the starting values of the context.  */
 444       A += A_save;
 445       B += B_save;
 446       C += C_save;
 447       D += D_save;
 448     }
 449
 450   /* Put checksum in context given as argument.  */
 451   ctx->A = A;
 452   ctx->B = B;
 453   ctx->C = C;
 454   ctx->D = D;
 455 }