lib/md4.c

   1 /* Functions to compute MD4 message digest of files or memory blocks.
   2    according to the definition of MD4 in RFC 1320 from April 1992.
   3    Copyright (C) 1995-1997, 1999-2003, 2005-2006, 2008-2011 Free Software
   4    Foundation, Inc.
   5
   6    This program is free software; you can redistribute it and/or modify it
   7    under the terms of the GNU General Public License as published by the
   8    Free Software Foundation; either version 2, or (at your option) any
   9    later version.
  10
  11    This program 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
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, write to the Free Software Foundation,
  18    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
  19
  20 /* Adapted by Simon Josefsson from gnulib md5.? and Libgcrypt
  21    cipher/md4.c . */
  22
  23 #include <config.h>
  24
  25 #include "md4.h"
  26
  27 #include <stddef.h>
  28 #include <stdlib.h>
  29 #include <stdlib.h>
  30 #include <string.h>
  31 #include <sys/types.h>
  32
  33 #if USE_UNLOCKED_IO
  34 # include "unlocked-io.h"
  35 #endif
  36
  37 #ifdef WORDS_BIGENDIAN
  38 # define SWAP(n)                                                        \
  39   (((n) << 24) | (((n) & 0xff00) << 8) | (((n) >> 8) & 0xff00) | ((n) >> 24))
  40 #else
  41 # define SWAP(n) (n)
  42 #endif
  43
  44 #define BLOCKSIZE 32768
  45 #if BLOCKSIZE % 64 != 0
  46 # error "invalid BLOCKSIZE"
  47 #endif
  48
  49 /* This array contains the bytes used to pad the buffer to the next
  50    64-byte boundary.  (RFC 1320, 3.1: Step 1)  */
  51 static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ...  */  };
  52
  53
  54 /* Initialize structure containing state of computation.
  55    (RFC 1320, 3.3: Step 3)  */
  56 void
  57 md4_init_ctx (struct md4_ctx *ctx)
  58 {
  59   ctx->A = 0x67452301;
  60   ctx->B = 0xefcdab89;
  61   ctx->C = 0x98badcfe;
  62   ctx->D = 0x10325476;
  63
  64   ctx->total[0] = ctx->total[1] = 0;
  65   ctx->buflen = 0;
  66 }
  67
  68 /* Copy the 4 byte value from v into the memory location pointed to by *cp,
  69    If your architecture allows unaligned access this is equivalent to
  70    * (uint32_t *) cp = v  */
  71 static inline void
  72 set_uint32 (char *cp, uint32_t v)
  73 {
  74   memcpy (cp, &v, sizeof v);
  75 }
  76
  77 /* Put result from CTX in first 16 bytes following RESBUF.  The result
  78    must be in little endian byte order.  */
  79 void *
  80 md4_read_ctx (const struct md4_ctx *ctx, void *resbuf)
  81 {
  82   char *r = resbuf;
  83   set_uint32 (r + 0 * sizeof ctx->A, SWAP (ctx->A));
  84   set_uint32 (r + 1 * sizeof ctx->B, SWAP (ctx->B));
  85   set_uint32 (r + 2 * sizeof ctx->C, SWAP (ctx->C));
  86   set_uint32 (r + 3 * sizeof ctx->D, SWAP (ctx->D));
  87
  88   return resbuf;
  89 }
  90
  91 /* Process the remaining bytes in the internal buffer and the usual
  92    prolog according to the standard and write the result to RESBUF.  */
  93 void *
  94 md4_finish_ctx (struct md4_ctx *ctx, void *resbuf)
  95 {
  96   /* Take yet unprocessed bytes into account.  */
  97   uint32_t bytes = ctx->buflen;
  98   size_t pad;
  99
 100   /* Now count remaining bytes.  */
 101   ctx->total[0] += bytes;
 102   if (ctx->total[0] < bytes)
 103     ++ctx->total[1];
 104
 105   pad = bytes >= 56 ? 64 + 56 - bytes : 56 - bytes;
 106   memcpy (&((char*)ctx->buffer)[bytes], fillbuf, pad);
 107
 108   /* Put the 64-bit file length in *bits* at the end of the buffer.  */
 109   ctx->buffer[(bytes + pad) / 4] = SWAP (ctx->total[0] << 3);
 110   ctx->buffer[(bytes + pad) / 4 + 1] = SWAP ((ctx->total[1] << 3) |
 111                                              (ctx->total[0] >> 29));
 112
 113   /* Process last bytes.  */
 114   md4_process_block (ctx->buffer, bytes + pad + 8, ctx);
 115
 116   return md4_read_ctx (ctx, resbuf);
 117 }
 118
 119 /* Compute MD4 message digest for bytes read from STREAM.  The
 120    resulting message digest number will be written into the 16 bytes
 121    beginning at RESBLOCK.  */
 122 int
 123 md4_stream (FILE * stream, void *resblock)
 124 {
 125   struct md4_ctx ctx;
 126   size_t sum;
 127
 128   char *buffer = malloc (BLOCKSIZE + 72);
 129   if (!buffer)
 130     return 1;
 131
 132   /* Initialize the computation context.  */
 133   md4_init_ctx (&ctx);
 134
 135   /* Iterate over full file contents.  */
 136   while (1)
 137     {
 138       /* We read the file in blocks of BLOCKSIZE bytes.  One call of the
 139          computation function processes the whole buffer so that with the
 140          next round of the loop another block can be read.  */
 141       size_t n;
 142       sum = 0;
 143
 144       /* Read block.  Take care for partial reads.  */
 145       while (1)
 146         {
 147           n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);
 148
 149           sum += n;
 150
 151           if (sum == BLOCKSIZE)
 152             break;
 153
 154           if (n == 0)
 155             {
 156               /* Check for the error flag IFF N == 0, so that we don't
 157                  exit the loop after a partial read due to e.g., EAGAIN
 158                  or EWOULDBLOCK.  */
 159               if (ferror (stream))
 160                 {
 161                   free (buffer);
 162                   return 1;
 163                 }
 164               goto process_partial_block;
 165             }
 166
 167           /* We've read at least one byte, so ignore errors.  But always
 168              check for EOF, since feof may be true even though N > 0.
 169              Otherwise, we could end up calling fread after EOF.  */
 170           if (feof (stream))
 171             goto process_partial_block;
 172         }
 173
 174       /* Process buffer with BLOCKSIZE bytes.  Note that
 175          BLOCKSIZE % 64 == 0
 176        */
 177       md4_process_block (buffer, BLOCKSIZE, &ctx);
 178     }
 179
 180 process_partial_block:;
 181
 182   /* Process any remaining bytes.  */
 183   if (sum > 0)
 184     md4_process_bytes (buffer, sum, &ctx);
 185
 186   /* Construct result in desired memory.  */
 187   md4_finish_ctx (&ctx, resblock);
 188   free (buffer);
 189   return 0;
 190 }
 191
 192 /* Compute MD4 message digest for LEN bytes beginning at BUFFER.  The
 193    result is always in little endian byte order, so that a byte-wise
 194    output yields to the wanted ASCII representation of the message
 195    digest.  */
 196 void *
 197 md4_buffer (const char *buffer, size_t len, void *resblock)
 198 {
 199   struct md4_ctx ctx;
 200
 201   /* Initialize the computation context.  */
 202   md4_init_ctx (&ctx);
 203
 204   /* Process whole buffer but last len % 64 bytes.  */
 205   md4_process_bytes (buffer, len, &ctx);
 206
 207   /* Put result in desired memory area.  */
 208   return md4_finish_ctx (&ctx, resblock);
 209 }
 210
 211 void
 212 md4_process_bytes (const void *buffer, size_t len, struct md4_ctx *ctx)
 213 {
 214   /* When we already have some bits in our internal buffer concatenate
 215      both inputs first.  */
 216   if (ctx->buflen != 0)
 217     {
 218       size_t left_over = ctx->buflen;
 219       size_t add = 128 - left_over > len ? len : 128 - left_over;
 220
 221       memcpy (&((char*)ctx->buffer)[left_over], buffer, add);
 222       ctx->buflen += add;
 223
 224       if (ctx->buflen > 64)
 225         {
 226           md4_process_block (ctx->buffer, ctx->buflen & ~63, ctx);
 227
 228           ctx->buflen &= 63;
 229           /* The regions in the following copy operation cannot overlap.  */
 230           memcpy (ctx->buffer, &((char*)ctx->buffer)[(left_over + add) & ~63],
 231                   ctx->buflen);
 232         }
 233
 234       buffer = (const char *) buffer + add;
 235       len -= add;
 236     }
 237
 238   /* Process available complete blocks.  */
 239   if (len >= 64)
 240     {
 241 #if !_STRING_ARCH_unaligned
 242       /* To check alignment gcc has an appropriate operator.  Other
 243          compilers don't.  */
 244 # if __GNUC__ >= 2
 245 #  define UNALIGNED_P(p) (((uintptr_t) p) % __alignof__ (uint32_t) != 0)
 246 # else
 247 #  define alignof(type) offsetof (struct { char c; type x; }, x)
 248 #  define UNALIGNED_P(p) (((size_t) p) % alignof (uint32_t) != 0)
 249 # endif
 250       if (UNALIGNED_P (buffer))
 251         while (len > 64)
 252           {
 253             md4_process_block (memcpy (ctx->buffer, buffer, 64), 64, ctx);
 254             buffer = (const char *) buffer + 64;
 255             len -= 64;
 256           }
 257       else
 258 #endif
 259         {
 260           md4_process_block (buffer, len & ~63, ctx);
 261           buffer = (const char *) buffer + (len & ~63);
 262           len &= 63;
 263         }
 264     }
 265
 266   /* Move remaining bytes in internal buffer.  */
 267   if (len > 0)
 268     {
 269       size_t left_over = ctx->buflen;
 270
 271       memcpy (&((char*)ctx->buffer)[left_over], buffer, len);
 272       left_over += len;
 273       if (left_over >= 64)
 274         {
 275           md4_process_block (ctx->buffer, 64, ctx);
 276           left_over -= 64;
 277           memcpy (ctx->buffer, &ctx->buffer[16], left_over);
 278         }
 279       ctx->buflen = left_over;
 280     }
 281 }
 282
 283 /* --- Code below is the primary difference between md5.c and md4.c --- */
 284
 285 /* MD4 round constants */
 286 #define K1 0x5a827999
 287 #define K2 0x6ed9eba1
 288
 289 /* Round functions.  */
 290 #define F(x, y, z) ((z) ^ ((x) & ((y) ^ (z))))
 291 #define G(x, y, z) (((x) & (y)) | ((x) & (z)) | ((y) & (z)))
 292 #define H(x, y, z) ((x) ^ (y) ^ (z))
 293 #define rol(x, n) (((x) << (n)) | ((uint32_t) (x) >> (32 - (n))))
 294 #define R1(a,b,c,d,k,s) a=rol(a+F(b,c,d)+x[k],s);
 295 #define R2(a,b,c,d,k,s) a=rol(a+G(b,c,d)+x[k]+K1,s);
 296 #define R3(a,b,c,d,k,s) a=rol(a+H(b,c,d)+x[k]+K2,s);
 297
 298 /* Process LEN bytes of BUFFER, accumulating context into CTX.
 299    It is assumed that LEN % 64 == 0.  */
 300
 301 void
 302 md4_process_block (const void *buffer, size_t len, struct md4_ctx *ctx)
 303 {
 304   const uint32_t *words = buffer;
 305   size_t nwords = len / sizeof (uint32_t);
 306   const uint32_t *endp = words + nwords;
 307   uint32_t x[16];
 308   uint32_t A = ctx->A;
 309   uint32_t B = ctx->B;
 310   uint32_t C = ctx->C;
 311   uint32_t D = ctx->D;
 312
 313   /* First increment the byte count.  RFC 1320 specifies the possible
 314      length of the file up to 2^64 bits.  Here we only compute the
 315      number of bytes.  Do a double word increment.  */
 316   ctx->total[0] += len;
 317   if (ctx->total[0] < len)
 318     ++ctx->total[1];
 319
 320   /* Process all bytes in the buffer with 64 bytes in each round of
 321      the loop.  */
 322   while (words < endp)
 323     {
 324       int t;
 325       for (t = 0; t < 16; t++)
 326         {
 327           x[t] = SWAP (*words);
 328           words++;
 329         }
 330
 331       /* Round 1.  */
 332       R1 (A, B, C, D, 0, 3);
 333       R1 (D, A, B, C, 1, 7);
 334       R1 (C, D, A, B, 2, 11);
 335       R1 (B, C, D, A, 3, 19);
 336       R1 (A, B, C, D, 4, 3);
 337       R1 (D, A, B, C, 5, 7);
 338       R1 (C, D, A, B, 6, 11);
 339       R1 (B, C, D, A, 7, 19);
 340       R1 (A, B, C, D, 8, 3);
 341       R1 (D, A, B, C, 9, 7);
 342       R1 (C, D, A, B, 10, 11);
 343       R1 (B, C, D, A, 11, 19);
 344       R1 (A, B, C, D, 12, 3);
 345       R1 (D, A, B, C, 13, 7);
 346       R1 (C, D, A, B, 14, 11);
 347       R1 (B, C, D, A, 15, 19);
 348
 349       /* Round 2.  */
 350       R2 (A, B, C, D, 0, 3);
 351       R2 (D, A, B, C, 4, 5);
 352       R2 (C, D, A, B, 8, 9);
 353       R2 (B, C, D, A, 12, 13);
 354       R2 (A, B, C, D, 1, 3);
 355       R2 (D, A, B, C, 5, 5);
 356       R2 (C, D, A, B, 9, 9);
 357       R2 (B, C, D, A, 13, 13);
 358       R2 (A, B, C, D, 2, 3);
 359       R2 (D, A, B, C, 6, 5);
 360       R2 (C, D, A, B, 10, 9);
 361       R2 (B, C, D, A, 14, 13);
 362       R2 (A, B, C, D, 3, 3);
 363       R2 (D, A, B, C, 7, 5);
 364       R2 (C, D, A, B, 11, 9);
 365       R2 (B, C, D, A, 15, 13);
 366
 367       /* Round 3.  */
 368       R3 (A, B, C, D, 0, 3);
 369       R3 (D, A, B, C, 8, 9);
 370       R3 (C, D, A, B, 4, 11);
 371       R3 (B, C, D, A, 12, 15);
 372       R3 (A, B, C, D, 2, 3);
 373       R3 (D, A, B, C, 10, 9);
 374       R3 (C, D, A, B, 6, 11);
 375       R3 (B, C, D, A, 14, 15);
 376       R3 (A, B, C, D, 1, 3);
 377       R3 (D, A, B, C, 9, 9);
 378       R3 (C, D, A, B, 5, 11);
 379       R3 (B, C, D, A, 13, 15);
 380       R3 (A, B, C, D, 3, 3);
 381       R3 (D, A, B, C, 11, 9);
 382       R3 (C, D, A, B, 7, 11);
 383       R3 (B, C, D, A, 15, 15);
 384
 385       A = ctx->A += A;
 386       B = ctx->B += B;
 387       C = ctx->C += C;
 388       D = ctx->D += D;
 389     }
 390 }