md5.c

   1 /*
   2  *  md5.c - Compute MD5 checksum of strings according to the
   3  *          definition of MD5 in RFC 1321 from April 1992.
   4  *
   5  *  Written by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1995.
   6  *
   7  *  Copyright (C) 1995-1999 Free Software Foundation, Inc.
   8  *  Copyright (C) 2001 Manuel Novoa III
   9  *  Copyright (C) 2003 Glenn L. McGrath
  10  *  Copyright (C) 2003 Erik Andersen
  11  *
  12  *  Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
  13  */
  14
  15 #include "blob.h" /* TODO: better include for bswap_32 compat */
  16
  17 #include <sys/types.h>
  18 #include <sys/stat.h>
  19
  20 #include <fcntl.h>
  21 #include <unistd.h>
  22
  23 #include "md5.h"
  24
  25 #if __BYTE_ORDER == __LITTLE_ENDIAN
  26 #define SWAP_LE32(x) (x)
  27 #else
  28 #define SWAP_LE32(x) bswap_32(x)
  29 #endif
  30
  31 /* Initialize structure containing state of computation.
  32  * (RFC 1321, 3.3: Step 3)
  33  */
  34 void md5_begin(md5_ctx_t *ctx)
  35 {
  36         ctx->A = 0x67452301;
  37         ctx->B = 0xefcdab89;
  38         ctx->C = 0x98badcfe;
  39         ctx->D = 0x10325476;
  40
  41         ctx->total = 0;
  42         ctx->buflen = 0;
  43 }
  44
  45 /* These are the four functions used in the four steps of the MD5 algorithm
  46  * and defined in the RFC 1321.  The first function is a little bit optimized
  47  * (as found in Colin Plumbs public domain implementation).
  48  * #define FF(b, c, d) ((b & c) | (~b & d))
  49  */
  50 # define FF(b, c, d) (d ^ (b & (c ^ d)))
  51 # define FG(b, c, d) FF (d, b, c)
  52 # define FH(b, c, d) (b ^ c ^ d)
  53 # define FI(b, c, d) (c ^ (b | ~d))
  54
  55 /* Hash a single block, 64 bytes long and 4-byte aligned. */
  56 static void md5_hash_block(const void *buffer, md5_ctx_t *ctx)
  57 {
  58         uint32_t correct_words[16];
  59         const uint32_t *words = buffer;
  60
  61         static const uint32_t C_array[] = {
  62                 /* round 1 */
  63                 0xd76aa478, 0xe8c7b756, 0x242070db, 0xc1bdceee,
  64                 0xf57c0faf, 0x4787c62a, 0xa8304613, 0xfd469501,
  65                 0x698098d8, 0x8b44f7af, 0xffff5bb1, 0x895cd7be,
  66                 0x6b901122, 0xfd987193, 0xa679438e, 0x49b40821,
  67                 /* round 2 */
  68                 0xf61e2562, 0xc040b340, 0x265e5a51, 0xe9b6c7aa,
  69                 0xd62f105d, 0x2441453, 0xd8a1e681, 0xe7d3fbc8,
  70                 0x21e1cde6, 0xc33707d6, 0xf4d50d87, 0x455a14ed,
  71                 0xa9e3e905, 0xfcefa3f8, 0x676f02d9, 0x8d2a4c8a,
  72                 /* round 3 */
  73                 0xfffa3942, 0x8771f681, 0x6d9d6122, 0xfde5380c,
  74                 0xa4beea44, 0x4bdecfa9, 0xf6bb4b60, 0xbebfbc70,
  75                 0x289b7ec6, 0xeaa127fa, 0xd4ef3085, 0x4881d05,
  76                 0xd9d4d039, 0xe6db99e5, 0x1fa27cf8, 0xc4ac5665,
  77                 /* round 4 */
  78                 0xf4292244, 0x432aff97, 0xab9423a7, 0xfc93a039,
  79                 0x655b59c3, 0x8f0ccc92, 0xffeff47d, 0x85845dd1,
  80                 0x6fa87e4f, 0xfe2ce6e0, 0xa3014314, 0x4e0811a1,
  81                 0xf7537e82, 0xbd3af235, 0x2ad7d2bb, 0xeb86d391
  82         };
  83
  84         static const char P_array[] = {
  85                 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,   /* 1 */
  86                 1, 6, 11, 0, 5, 10, 15, 4, 9, 14, 3, 8, 13, 2, 7, 12,   /* 2 */
  87                 5, 8, 11, 14, 1, 4, 7, 10, 13, 0, 3, 6, 9, 12, 15, 2,   /* 3 */
  88                 0, 7, 14, 5, 12, 3, 10, 1, 8, 15, 6, 13, 4, 11, 2, 9    /* 4 */
  89         };
  90
  91         static const char S_array[] = {
  92                 7, 12, 17, 22,
  93                 5, 9, 14, 20,
  94                 4, 11, 16, 23,
  95                 6, 10, 15, 21
  96         };
  97
  98         uint32_t A = ctx->A;
  99         uint32_t B = ctx->B;
 100         uint32_t C = ctx->C;
 101         uint32_t D = ctx->D;
 102
 103         uint32_t *cwp = correct_words;
 104
 105 #  define CYCLIC(w, s) (w = (w << s) | (w >> (32 - s)))
 106
 107         const uint32_t *pc;
 108         const char *pp;
 109         const char *ps;
 110         int i;
 111         uint32_t temp;
 112
 113         for (i = 0; i < 16; i++) {
 114                 cwp[i] = SWAP_LE32(words[i]);
 115         }
 116
 117         pc = C_array;
 118         pp = P_array;
 119         ps = S_array;
 120
 121         for (i = 0; i < 16; i++) {
 122                 temp = A + FF(B, C, D) + cwp[(int) (*pp++)] + *pc++;
 123                 CYCLIC(temp, ps[i & 3]);
 124                 temp += B;
 125                 A = D;
 126                 D = C;
 127                 C = B;
 128                 B = temp;
 129         }
 130
 131         ps += 4;
 132         for (i = 0; i < 16; i++) {
 133                 temp = A + FG(B, C, D) + cwp[(int) (*pp++)] + *pc++;
 134                 CYCLIC(temp, ps[i & 3]);
 135                 temp += B;
 136                 A = D;
 137                 D = C;
 138                 C = B;
 139                 B = temp;
 140         }
 141         ps += 4;
 142         for (i = 0; i < 16; i++) {
 143                 temp = A + FH(B, C, D) + cwp[(int) (*pp++)] + *pc++;
 144                 CYCLIC(temp, ps[i & 3]);
 145                 temp += B;
 146                 A = D;
 147                 D = C;
 148                 C = B;
 149                 B = temp;
 150         }
 151         ps += 4;
 152         for (i = 0; i < 16; i++) {
 153                 temp = A + FI(B, C, D) + cwp[(int) (*pp++)] + *pc++;
 154                 CYCLIC(temp, ps[i & 3]);
 155                 temp += B;
 156                 A = D;
 157                 D = C;
 158                 C = B;
 159                 B = temp;
 160         }
 161
 162
 163         ctx->A += A;
 164         ctx->B += B;
 165         ctx->C += C;
 166         ctx->D += D;
 167 }
 168
 169 /* Feed data through a temporary buffer to call md5_hash_aligned_block()
 170  * with chunks of data that are 4-byte aligned and a multiple of 64 bytes.
 171  * This function's internal buffer remembers previous data until it has 64
 172  * bytes worth to pass on.  Call md5_end() to flush this buffer. */
 173
 174 void md5_hash(const void *buffer, size_t len, md5_ctx_t *ctx)
 175 {
 176         char *buf = (char *)buffer;
 177
 178         /* RFC 1321 specifies the possible length of the file up to 2^64 bits,
 179          * Here we only track the number of bytes.  */
 180
 181         ctx->total += len;
 182
 183         // Process all input.
 184
 185         while (len) {
 186                 unsigned i = 64 - ctx->buflen;
 187
 188                 // Copy data into aligned buffer.
 189
 190                 if (i > len)
 191                         i = len;
 192                 memcpy(ctx->buffer + ctx->buflen, buf, i);
 193                 len -= i;
 194                 ctx->buflen += i;
 195                 buf += i;
 196
 197                 // When buffer fills up, process it.
 198
 199                 if (ctx->buflen == 64) {
 200                         md5_hash_block(ctx->buffer, ctx);
 201                         ctx->buflen = 0;
 202                 }
 203         }
 204 }
 205
 206 /* Process the remaining bytes in the buffer and put result from CTX
 207  * in first 16 bytes following RESBUF.  The result is always in little
 208  * endian byte order, so that a byte-wise output yields to the wanted
 209  * ASCII representation of the message digest.
 210  *
 211  * IMPORTANT: On some systems it is required that RESBUF is correctly
 212  * aligned for a 32 bits value.
 213  */
 214 void md5_end(void *resbuf, md5_ctx_t *ctx)
 215 {
 216         char *buf = ctx->buffer;
 217         int i;
 218
 219         /* Pad data to block size.  */
 220
 221         buf[ctx->buflen++] = 0x80;
 222         memset(buf + ctx->buflen, 0, 128 - ctx->buflen);
 223
 224         /* Put the 64-bit file length in *bits* at the end of the buffer.  */
 225         ctx->total <<= 3;
 226         if (ctx->buflen > 56)
 227                 buf += 64;
 228
 229         for (i = 0; i < 8; i++)
 230                 buf[56 + i] = ctx->total >> (i*8);
 231
 232         /* Process last bytes.  */
 233         if (buf != ctx->buffer)
 234                 md5_hash_block(ctx->buffer, ctx);
 235         md5_hash_block(buf, ctx);
 236
 237         /* Put result from CTX in first 16 bytes following RESBUF.  The result is
 238          * always in little endian byte order, so that a byte-wise output yields
 239          * to the wanted ASCII representation of the message digest.
 240          *
 241          * IMPORTANT: On some systems it is required that RESBUF is correctly
 242          * aligned for a 32 bits value.
 243          */
 244         ((uint32_t *) resbuf)[0] = SWAP_LE32(ctx->A);
 245         ((uint32_t *) resbuf)[1] = SWAP_LE32(ctx->B);
 246         ((uint32_t *) resbuf)[2] = SWAP_LE32(ctx->C);
 247         ((uint32_t *) resbuf)[3] = SWAP_LE32(ctx->D);
 248 }
 249
 250 int md5sum(char *file, uint32_t *md5)
 251 {
 252         char buf[256];
 253         md5_ctx_t ctx;
 254         int len, fd;
 255         int ret = 0;
 256
 257         memset(md5, 0, sizeof(*md5) * 4);
 258
 259         fd = open(file, O_RDONLY);
 260         if (fd < 0)
 261                 return -1;
 262
 263         md5_begin(&ctx);
 264         do {
 265                 len = read(fd, buf, sizeof(buf));
 266                 if (len < 0) {
 267                         if (errno == EINTR)
 268                                 continue;
 269
 270                         ret = -1;
 271                         goto out;
 272                 }
 273                 if (!len)
 274                         break;
 275
 276                 md5_hash(buf, len, &ctx);
 277         } while(1);
 278
 279         md5_end(md5, &ctx);
 280 out:
 281         close(fd);
 282
 283         return ret;
 284 }