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, 2008-2024 Free Software
   4    Foundation, Inc.
   5
   6    This file is free software: you can redistribute it and/or modify
   7    it under the terms of the GNU Lesser General Public License as
   8    published by the Free Software Foundation; either version 2.1 of the
   9    License, or (at your option) any later version.
  10
  11    This file 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 Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public License
  17    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  18
  19 /* Adapted by Simon Josefsson from gnulib md5.? and Libgcrypt
  20    cipher/md4.c . */
  21
  22 #include <config.h>
  23
  24 /* Specification.  */
  25 #include "md4.h"
  26
  27 #include <stdint.h>
  28 #include <string.h>
  29 #include <sys/types.h>
  30
  31 #include <byteswap.h>
  32 #ifdef WORDS_BIGENDIAN
  33 # define SWAP(n) bswap_32 (n)
  34 #else
  35 # define SWAP(n) (n)
  36 #endif
  37
  38 /* This array contains the bytes used to pad the buffer to the next
  39    64-byte boundary.  (RFC 1320, 3.1: Step 1)  */
  40 static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ...  */  };
  41
  42
  43 /* Initialize structure containing state of computation.
  44    (RFC 1320, 3.3: Step 3)  */
  45 void
  46 md4_init_ctx (struct md4_ctx *ctx)
  47 {
  48   ctx->A = 0x67452301;
  49   ctx->B = 0xefcdab89;
  50   ctx->C = 0x98badcfe;
  51   ctx->D = 0x10325476;
  52
  53   ctx->total[0] = ctx->total[1] = 0;
  54   ctx->buflen = 0;
  55 }
  56
  57 /* Copy the 4 byte value from v into the memory location pointed to by *cp,
  58    If your architecture allows unaligned access this is equivalent to
  59    * (uint32_t *) cp = v  */
  60 static void
  61 set_uint32 (char *cp, uint32_t v)
  62 {
  63   memcpy (cp, &v, sizeof v);
  64 }
  65
  66 /* Put result from CTX in first 16 bytes following RESBUF.  The result
  67    must be in little endian byte order.  */
  68 void *
  69 md4_read_ctx (const struct md4_ctx *ctx, void *resbuf)
  70 {
  71   char *r = resbuf;
  72   set_uint32 (r + 0 * sizeof ctx->A, SWAP (ctx->A));
  73   set_uint32 (r + 1 * sizeof ctx->B, SWAP (ctx->B));
  74   set_uint32 (r + 2 * sizeof ctx->C, SWAP (ctx->C));
  75   set_uint32 (r + 3 * sizeof ctx->D, SWAP (ctx->D));
  76
  77   return resbuf;
  78 }
  79
  80 /* Process the remaining bytes in the internal buffer and the usual
  81    prolog according to the standard and write the result to RESBUF.  */
  82 void *
  83 md4_finish_ctx (struct md4_ctx *ctx, void *resbuf)
  84 {
  85   /* Take yet unprocessed bytes into account.  */
  86   uint32_t bytes = ctx->buflen;
  87   size_t pad;
  88
  89   /* Now count remaining bytes.  */
  90   ctx->total[0] += bytes;
  91   if (ctx->total[0] < bytes)
  92     ++ctx->total[1];
  93
  94   pad = bytes >= 56 ? 64 + 56 - bytes : 56 - bytes;
  95   memcpy (&((char*)ctx->buffer)[bytes], fillbuf, pad);
  96
  97   /* Put the 64-bit file length in *bits* at the end of the buffer.  */
  98   ctx->buffer[(bytes + pad) / 4] = SWAP (ctx->total[0] << 3);
  99   ctx->buffer[(bytes + pad) / 4 + 1] = SWAP ((ctx->total[1] << 3) |
 100                                              (ctx->total[0] >> 29));
 101
 102   /* Process last bytes.  */
 103   md4_process_block (ctx->buffer, bytes + pad + 8, ctx);
 104
 105   return md4_read_ctx (ctx, resbuf);
 106 }
 107
 108 /* Compute MD4 message digest for LEN bytes beginning at BUFFER.  The
 109    result is always in little endian byte order, so that a byte-wise
 110    output yields to the wanted ASCII representation of the message
 111    digest.  */
 112 void *
 113 md4_buffer (const char *buffer, size_t len, void *resblock)
 114 {
 115   struct md4_ctx ctx;
 116
 117   /* Initialize the computation context.  */
 118   md4_init_ctx (&ctx);
 119
 120   /* Process whole buffer but last len % 64 bytes.  */
 121   md4_process_bytes (buffer, len, &ctx);
 122
 123   /* Put result in desired memory area.  */
 124   return md4_finish_ctx (&ctx, resblock);
 125 }
 126
 127 void
 128 md4_process_bytes (const void *buffer, size_t len, struct md4_ctx *ctx)
 129 {
 130   /* When we already have some bits in our internal buffer concatenate
 131      both inputs first.  */
 132   if (ctx->buflen != 0)
 133     {
 134       size_t left_over = ctx->buflen;
 135       size_t add = 128 - left_over > len ? len : 128 - left_over;
 136
 137       memcpy (&((char*)ctx->buffer)[left_over], buffer, add);
 138       ctx->buflen += add;
 139
 140       if (ctx->buflen > 64)
 141         {
 142           md4_process_block (ctx->buffer, ctx->buflen & ~63, ctx);
 143
 144           ctx->buflen &= 63;
 145           /* The regions in the following copy operation cannot overlap.  */
 146           memcpy (ctx->buffer, &((char*)ctx->buffer)[(left_over + add) & ~63],
 147                   ctx->buflen);
 148         }
 149
 150       buffer = (const char *) buffer + add;
 151       len -= add;
 152     }
 153
 154   /* Process available complete blocks.  */
 155   if (len >= 64)
 156     {
 157 #if !(_STRING_ARCH_unaligned || _STRING_INLINE_unaligned)
 158 # define UNALIGNED_P(p) ((uintptr_t) (p) % alignof (uint32_t) != 0)
 159       if (UNALIGNED_P (buffer))
 160         while (len > 64)
 161           {
 162             md4_process_block (memcpy (ctx->buffer, buffer, 64), 64, ctx);
 163             buffer = (const char *) buffer + 64;
 164             len -= 64;
 165           }
 166       else
 167 #endif
 168         {
 169           md4_process_block (buffer, len & ~63, ctx);
 170           buffer = (const char *) buffer + (len & ~63);
 171           len &= 63;
 172         }
 173     }
 174
 175   /* Move remaining bytes in internal buffer.  */
 176   if (len > 0)
 177     {
 178       size_t left_over = ctx->buflen;
 179
 180       memcpy (&((char*)ctx->buffer)[left_over], buffer, len);
 181       left_over += len;
 182       if (left_over >= 64)
 183         {
 184           md4_process_block (ctx->buffer, 64, ctx);
 185           left_over -= 64;
 186           memcpy (ctx->buffer, &ctx->buffer[16], left_over);
 187         }
 188       ctx->buflen = left_over;
 189     }
 190 }
 191
 192 /* --- Code below is the primary difference between md5.c and md4.c --- */
 193
 194 /* MD4 round constants */
 195 #define K1 0x5a827999
 196 #define K2 0x6ed9eba1
 197
 198 /* Round functions.  */
 199 #define F(x, y, z) ((z) ^ ((x) & ((y) ^ (z))))
 200 #define G(x, y, z) (((x) & (y)) | ((x) & (z)) | ((y) & (z)))
 201 #define H(x, y, z) ((x) ^ (y) ^ (z))
 202 #define rol(x, n) (((x) << (n)) | ((uint32_t) (x) >> (32 - (n))))
 203 #define R1(a,b,c,d,k,s) a=rol(a+F(b,c,d)+x[k],s);
 204 #define R2(a,b,c,d,k,s) a=rol(a+G(b,c,d)+x[k]+K1,s);
 205 #define R3(a,b,c,d,k,s) a=rol(a+H(b,c,d)+x[k]+K2,s);
 206
 207 /* Process LEN bytes of BUFFER, accumulating context into CTX.
 208    It is assumed that LEN % 64 == 0.  */
 209
 210 void
 211 md4_process_block (const void *buffer, size_t len, struct md4_ctx *ctx)
 212 {
 213   const uint32_t *words = buffer;
 214   size_t nwords = len / sizeof (uint32_t);
 215   const uint32_t *endp = words + nwords;
 216   uint32_t x[16];
 217   uint32_t A = ctx->A;
 218   uint32_t B = ctx->B;
 219   uint32_t C = ctx->C;
 220   uint32_t D = ctx->D;
 221   uint32_t lolen = len;
 222
 223   /* First increment the byte count.  RFC 1320 specifies the possible
 224      length of the file up to 2^64 bits.  Here we only compute the
 225      number of bytes.  Do a double word increment.  */
 226   ctx->total[0] += lolen;
 227   ctx->total[1] += (len >> 31 >> 1) + (ctx->total[0] < lolen);
 228
 229   /* Process all bytes in the buffer with 64 bytes in each round of
 230      the loop.  */
 231   while (words < endp)
 232     {
 233       int t;
 234       for (t = 0; t < 16; t++)
 235         {
 236           x[t] = SWAP (*words);
 237           words++;
 238         }
 239
 240       /* Round 1.  */
 241       R1 (A, B, C, D, 0, 3);
 242       R1 (D, A, B, C, 1, 7);
 243       R1 (C, D, A, B, 2, 11);
 244       R1 (B, C, D, A, 3, 19);
 245       R1 (A, B, C, D, 4, 3);
 246       R1 (D, A, B, C, 5, 7);
 247       R1 (C, D, A, B, 6, 11);
 248       R1 (B, C, D, A, 7, 19);
 249       R1 (A, B, C, D, 8, 3);
 250       R1 (D, A, B, C, 9, 7);
 251       R1 (C, D, A, B, 10, 11);
 252       R1 (B, C, D, A, 11, 19);
 253       R1 (A, B, C, D, 12, 3);
 254       R1 (D, A, B, C, 13, 7);
 255       R1 (C, D, A, B, 14, 11);
 256       R1 (B, C, D, A, 15, 19);
 257
 258       /* Round 2.  */
 259       R2 (A, B, C, D, 0, 3);
 260       R2 (D, A, B, C, 4, 5);
 261       R2 (C, D, A, B, 8, 9);
 262       R2 (B, C, D, A, 12, 13);
 263       R2 (A, B, C, D, 1, 3);
 264       R2 (D, A, B, C, 5, 5);
 265       R2 (C, D, A, B, 9, 9);
 266       R2 (B, C, D, A, 13, 13);
 267       R2 (A, B, C, D, 2, 3);
 268       R2 (D, A, B, C, 6, 5);
 269       R2 (C, D, A, B, 10, 9);
 270       R2 (B, C, D, A, 14, 13);
 271       R2 (A, B, C, D, 3, 3);
 272       R2 (D, A, B, C, 7, 5);
 273       R2 (C, D, A, B, 11, 9);
 274       R2 (B, C, D, A, 15, 13);
 275
 276       /* Round 3.  */
 277       R3 (A, B, C, D, 0, 3);
 278       R3 (D, A, B, C, 8, 9);
 279       R3 (C, D, A, B, 4, 11);
 280       R3 (B, C, D, A, 12, 15);
 281       R3 (A, B, C, D, 2, 3);
 282       R3 (D, A, B, C, 10, 9);
 283       R3 (C, D, A, B, 6, 11);
 284       R3 (B, C, D, A, 14, 15);
 285       R3 (A, B, C, D, 1, 3);
 286       R3 (D, A, B, C, 9, 9);
 287       R3 (C, D, A, B, 5, 11);
 288       R3 (B, C, D, A, 13, 15);
 289       R3 (A, B, C, D, 3, 3);
 290       R3 (D, A, B, C, 11, 9);
 291       R3 (C, D, A, B, 7, 11);
 292       R3 (B, C, D, A, 15, 15);
 293
 294       A = ctx->A += A;
 295       B = ctx->B += B;
 296       C = ctx->C += C;
 297       D = ctx->D += D;
 298     }
 299 }