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