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