md5c.c

   1 /*
   2  * This code implements the MD5 message-digest algorithm.
   3  * The algorithm is due to Ron Rivest.  This code was
   4  * written by Colin Plumb in 1993, no copyright is claimed.
   5  * This code is in the public domain; do with it what you wish.
   6  *
   7  * Equivalent code is available from RSA Data Security, Inc.
   8  * This code has been tested against that, and is equivalent,
   9  * except that you don't need to include two pages of legalese
  10  * with every copy.
  11  *
  12  * To compute the message digest of a chunk of bytes, declare an
  13  * MD5Context structure, pass it to MD5Init, call MD5Update as
  14  * needed on buffers full of bytes, and then call MD5Final, which
  15  * will fill a supplied 16-byte array with the digest.
  16  */
  17
  18 #include "md5.h"
  19 #include <string.h>             /* for memcpy() */
  20
  21 #ifdef WORDS_LITTEENDIAN
  22 #define byteReverse(buf, len)   /* Nothing */
  23 #else
  24 static void byteReverse(unsigned char *buf, unsigned longs);
  25
  26 /*
  27  * Note: this code is harmless on little-endian machines.
  28  */
  29 static void byteReverse(unsigned char *buf, unsigned longs)
  30 {
  31     uint32_t t;
  32     do {
  33         t = (uint32_t) ((unsigned) buf[3] << 8 | buf[2]) << 16 |
  34             ((unsigned) buf[1] << 8 | buf[0]);
  35         *(uint32_t *) buf = t;
  36         buf += 4;
  37     } while (--longs);
  38 }
  39 #endif
  40
  41 /*
  42  * Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
  43  * initialization constants.
  44  */
  45 void MD5Init(MD5_CTX *ctx)
  46 {
  47     ctx->buf[0] = 0x67452301;
  48     ctx->buf[1] = 0xefcdab89;
  49     ctx->buf[2] = 0x98badcfe;
  50     ctx->buf[3] = 0x10325476;
  51
  52     ctx->bits[0] = 0;
  53     ctx->bits[1] = 0;
  54 }
  55
  56 /*
  57  * Update context to reflect the concatenation of another buffer full
  58  * of bytes.
  59  */
  60 void MD5Update(MD5_CTX *ctx, unsigned char const *buf, unsigned len)
  61 {
  62     uint32_t t;
  63
  64     /* Update bitcount */
  65
  66     t = ctx->bits[0];
  67     if ((ctx->bits[0] = t + ((uint32_t) len << 3)) < t)
  68         ctx->bits[1]++;         /* Carry from low to high */
  69     ctx->bits[1] += len >> 29;
  70
  71     t = (t >> 3) & 0x3f;        /* Bytes already in shsInfo->data */
  72
  73     /* Handle any leading odd-sized chunks */
  74
  75     if (t) {
  76         unsigned char *p = (unsigned char *) ctx->in + t;
  77
  78         t = 64 - t;
  79         if (len < t) {
  80             memcpy(p, buf, len);
  81             return;
  82         }
  83         memcpy(p, buf, t);
  84         byteReverse(ctx->in, 16);
  85         MD5Transform(ctx->buf, (uint32_t *) ctx->in);
  86         buf += t;
  87         len -= t;
  88     }
  89     /* Process data in 64-byte chunks */
  90
  91     while (len >= 64) {
  92         memcpy(ctx->in, buf, 64);
  93         byteReverse(ctx->in, 16);
  94         MD5Transform(ctx->buf, (uint32_t *) ctx->in);
  95         buf += 64;
  96         len -= 64;
  97     }
  98
  99     /* Handle any remaining bytes of data. */
 100
 101     memcpy(ctx->in, buf, len);
 102 }
 103
 104 /*
 105  * Final wrapup - pad to 64-byte boundary with the bit pattern
 106  * 1 0* (64-bit count of bits processed, MSB-first)
 107  */
 108 void MD5Final(unsigned char digest[16], MD5_CTX *ctx)
 109 {
 110     unsigned count;
 111     unsigned char *p;
 112
 113     /* Compute number of bytes mod 64 */
 114     count = (ctx->bits[0] >> 3) & 0x3F;
 115
 116     /* Set the first char of padding to 0x80.  This is safe since there is
 117        always at least one byte free */
 118     p = ctx->in + count;
 119     *p++ = 0x80;
 120
 121     /* Bytes of padding needed to make 64 bytes */
 122     count = 64 - 1 - count;
 123
 124     /* Pad out to 56 mod 64 */
 125     if (count < 8) {
 126         /* Two lots of padding:  Pad the first block to 64 bytes */
 127         memset(p, 0, count);
 128         byteReverse(ctx->in, 16);
 129         MD5Transform(ctx->buf, (uint32_t *) ctx->in);
 130
 131         /* Now fill the next block with 56 bytes */
 132         memset(ctx->in, 0, 56);
 133     } else {
 134         /* Pad block to 56 bytes */
 135         memset(p, 0, count - 8);
 136     }
 137     byteReverse(ctx->in, 14);
 138
 139     /* Append length in bits and transform */
 140     ((uint32_t *) ctx->in)[14] = ctx->bits[0];
 141     ((uint32_t *) ctx->in)[15] = ctx->bits[1];
 142
 143     MD5Transform(ctx->buf, (uint32_t *) ctx->in);
 144     byteReverse((unsigned char *) ctx->buf, 4);
 145     memcpy(digest, ctx->buf, 16);
 146     memset((char *) ctx, 0, sizeof(ctx));       /* In case it's sensitive */
 147 }
 148
 149 /* The four core functions - F1 is optimized somewhat */
 150
 151 /* #define F1(x, y, z) (x & y | ~x & z) */
 152 #define F1(x, y, z) (z ^ (x & (y ^ z)))
 153 #define F2(x, y, z) F1(z, x, y)
 154 #define F3(x, y, z) (x ^ y ^ z)
 155 #define F4(x, y, z) (y ^ (x | ~z))
 156
 157 /* This is the central step in the MD5 algorithm. */
 158 #define MD5STEP(f, w, x, y, z, data, s) \
 159         ( w += f(x, y, z) + data,  w = w<<s | w>>(32-s),  w += x )
 160
 161 /*
 162  * The core of the MD5 algorithm, this alters an existing MD5 hash to
 163  * reflect the addition of 16 longwords of new data.  MD5Update blocks
 164  * the data and converts bytes into longwords for this routine.
 165  */
 166 void MD5Transform(uint32_t buf[4], uint32_t const in[16])
 167 {
 168     register uint32_t a, b, c, d;
 169
 170     a = buf[0];
 171     b = buf[1];
 172     c = buf[2];
 173     d = buf[3];
 174
 175     MD5STEP(F1, a, b, c, d, in[0] + 0xd76aa478, 7);
 176     MD5STEP(F1, d, a, b, c, in[1] + 0xe8c7b756, 12);
 177     MD5STEP(F1, c, d, a, b, in[2] + 0x242070db, 17);
 178     MD5STEP(F1, b, c, d, a, in[3] + 0xc1bdceee, 22);
 179     MD5STEP(F1, a, b, c, d, in[4] + 0xf57c0faf, 7);
 180     MD5STEP(F1, d, a, b, c, in[5] + 0x4787c62a, 12);
 181     MD5STEP(F1, c, d, a, b, in[6] + 0xa8304613, 17);
 182     MD5STEP(F1, b, c, d, a, in[7] + 0xfd469501, 22);
 183     MD5STEP(F1, a, b, c, d, in[8] + 0x698098d8, 7);
 184     MD5STEP(F1, d, a, b, c, in[9] + 0x8b44f7af, 12);
 185     MD5STEP(F1, c, d, a, b, in[10] + 0xffff5bb1, 17);
 186     MD5STEP(F1, b, c, d, a, in[11] + 0x895cd7be, 22);
 187     MD5STEP(F1, a, b, c, d, in[12] + 0x6b901122, 7);
 188     MD5STEP(F1, d, a, b, c, in[13] + 0xfd987193, 12);
 189     MD5STEP(F1, c, d, a, b, in[14] + 0xa679438e, 17);
 190     MD5STEP(F1, b, c, d, a, in[15] + 0x49b40821, 22);
 191
 192     MD5STEP(F2, a, b, c, d, in[1] + 0xf61e2562, 5);
 193     MD5STEP(F2, d, a, b, c, in[6] + 0xc040b340, 9);
 194     MD5STEP(F2, c, d, a, b, in[11] + 0x265e5a51, 14);
 195     MD5STEP(F2, b, c, d, a, in[0] + 0xe9b6c7aa, 20);
 196     MD5STEP(F2, a, b, c, d, in[5] + 0xd62f105d, 5);
 197     MD5STEP(F2, d, a, b, c, in[10] + 0x02441453, 9);
 198     MD5STEP(F2, c, d, a, b, in[15] + 0xd8a1e681, 14);
 199     MD5STEP(F2, b, c, d, a, in[4] + 0xe7d3fbc8, 20);
 200     MD5STEP(F2, a, b, c, d, in[9] + 0x21e1cde6, 5);
 201     MD5STEP(F2, d, a, b, c, in[14] + 0xc33707d6, 9);
 202     MD5STEP(F2, c, d, a, b, in[3] + 0xf4d50d87, 14);
 203     MD5STEP(F2, b, c, d, a, in[8] + 0x455a14ed, 20);
 204     MD5STEP(F2, a, b, c, d, in[13] + 0xa9e3e905, 5);
 205     MD5STEP(F2, d, a, b, c, in[2] + 0xfcefa3f8, 9);
 206     MD5STEP(F2, c, d, a, b, in[7] + 0x676f02d9, 14);
 207     MD5STEP(F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);
 208
 209     MD5STEP(F3, a, b, c, d, in[5] + 0xfffa3942, 4);
 210     MD5STEP(F3, d, a, b, c, in[8] + 0x8771f681, 11);
 211     MD5STEP(F3, c, d, a, b, in[11] + 0x6d9d6122, 16);
 212     MD5STEP(F3, b, c, d, a, in[14] + 0xfde5380c, 23);
 213     MD5STEP(F3, a, b, c, d, in[1] + 0xa4beea44, 4);
 214     MD5STEP(F3, d, a, b, c, in[4] + 0x4bdecfa9, 11);
 215     MD5STEP(F3, c, d, a, b, in[7] + 0xf6bb4b60, 16);
 216     MD5STEP(F3, b, c, d, a, in[10] + 0xbebfbc70, 23);
 217     MD5STEP(F3, a, b, c, d, in[13] + 0x289b7ec6, 4);
 218     MD5STEP(F3, d, a, b, c, in[0] + 0xeaa127fa, 11);
 219     MD5STEP(F3, c, d, a, b, in[3] + 0xd4ef3085, 16);
 220     MD5STEP(F3, b, c, d, a, in[6] + 0x04881d05, 23);
 221     MD5STEP(F3, a, b, c, d, in[9] + 0xd9d4d039, 4);
 222     MD5STEP(F3, d, a, b, c, in[12] + 0xe6db99e5, 11);
 223     MD5STEP(F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);
 224     MD5STEP(F3, b, c, d, a, in[2] + 0xc4ac5665, 23);
 225
 226     MD5STEP(F4, a, b, c, d, in[0] + 0xf4292244, 6);
 227     MD5STEP(F4, d, a, b, c, in[7] + 0x432aff97, 10);
 228     MD5STEP(F4, c, d, a, b, in[14] + 0xab9423a7, 15);
 229     MD5STEP(F4, b, c, d, a, in[5] + 0xfc93a039, 21);
 230     MD5STEP(F4, a, b, c, d, in[12] + 0x655b59c3, 6);
 231     MD5STEP(F4, d, a, b, c, in[3] + 0x8f0ccc92, 10);
 232     MD5STEP(F4, c, d, a, b, in[10] + 0xffeff47d, 15);
 233     MD5STEP(F4, b, c, d, a, in[1] + 0x85845dd1, 21);
 234     MD5STEP(F4, a, b, c, d, in[8] + 0x6fa87e4f, 6);
 235     MD5STEP(F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);
 236     MD5STEP(F4, c, d, a, b, in[6] + 0xa3014314, 15);
 237     MD5STEP(F4, b, c, d, a, in[13] + 0x4e0811a1, 21);
 238     MD5STEP(F4, a, b, c, d, in[4] + 0xf7537e82, 6);
 239     MD5STEP(F4, d, a, b, c, in[11] + 0xbd3af235, 10);
 240     MD5STEP(F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15);
 241     MD5STEP(F4, b, c, d, a, in[9] + 0xeb86d391, 21);
 242
 243     buf[0] += a;
 244     buf[1] += b;
 245     buf[2] += c;
 246     buf[3] += d;
 247 }