md5_utils.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  * Changed so as no longer to depend on Colin Plumb's `usual.h' header
  18  * definitions
  19  *  - Ian Jackson <ian@chiark.greenend.org.uk>.
  20  * Still in the public domain.
  21  */
  22
  23 #include <string.h>   /* for memcpy() */
  24
  25 #include "md5_utils.h"
  26
  27 void
  28 byteSwap(UWORD32 *buf, unsigned words)
  29 {
  30     md5byte *p;
  31
  32     /* Only swap bytes for big endian machines */
  33     int i = 1;
  34
  35     if (*(char *)&i == 1)
  36         return;
  37
  38     p = (md5byte *)buf;
  39
  40     do
  41     {
  42         *buf++ = (UWORD32)((unsigned)p[3] << 8 | p[2]) << 16 |
  43                  ((unsigned)p[1] << 8 | p[0]);
  44         p += 4;
  45     }
  46     while (--words);
  47 }
  48
  49 /*
  50  * Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
  51  * initialization constants.
  52  */
  53 void
  54 MD5Init(struct MD5Context *ctx)
  55 {
  56     ctx->buf[0] = 0x67452301;
  57     ctx->buf[1] = 0xefcdab89;
  58     ctx->buf[2] = 0x98badcfe;
  59     ctx->buf[3] = 0x10325476;
  60
  61     ctx->bytes[0] = 0;
  62     ctx->bytes[1] = 0;
  63 }
  64
  65 /*
  66  * Update context to reflect the concatenation of another buffer full
  67  * of bytes.
  68  */
  69 void
  70 MD5Update(struct MD5Context *ctx, md5byte const *buf, unsigned len)
  71 {
  72     UWORD32 t;
  73
  74     /* Update byte count */
  75
  76     t = ctx->bytes[0];
  77
  78     if ((ctx->bytes[0] = t + len) < t)
  79         ctx->bytes[1]++;  /* Carry from low to high */
  80
  81     t = 64 - (t & 0x3f);  /* Space available in ctx->in (at least 1) */
  82
  83     if (t > len)
  84     {
  85         memcpy((md5byte *)ctx->in + 64 - t, buf, len);
  86         return;
  87     }
  88
  89     /* First chunk is an odd size */
  90     memcpy((md5byte *)ctx->in + 64 - t, buf, t);
  91     byteSwap(ctx->in, 16);
  92     MD5Transform(ctx->buf, ctx->in);
  93     buf += t;
  94     len -= t;
  95
  96     /* Process data in 64-byte chunks */
  97     while (len >= 64)
  98     {
  99         memcpy(ctx->in, buf, 64);
 100         byteSwap(ctx->in, 16);
 101         MD5Transform(ctx->buf, ctx->in);
 102         buf += 64;
 103         len -= 64;
 104     }
 105
 106     /* Handle any remaining bytes of data. */
 107     memcpy(ctx->in, buf, len);
 108 }
 109
 110 /*
 111  * Final wrapup - pad to 64-byte boundary with the bit pattern
 112  * 1 0* (64-bit count of bits processed, MSB-first)
 113  */
 114 void
 115 MD5Final(md5byte digest[16], struct MD5Context *ctx)
 116 {
 117     int count = ctx->bytes[0] & 0x3f; /* Number of bytes in ctx->in */
 118     md5byte *p = (md5byte *)ctx->in + count;
 119
 120     /* Set the first char of padding to 0x80.  There is always room. */
 121     *p++ = 0x80;
 122
 123     /* Bytes of padding needed to make 56 bytes (-8..55) */
 124     count = 56 - 1 - count;
 125
 126     if (count < 0)    /* Padding forces an extra block */
 127     {
 128         memset(p, 0, count + 8);
 129         byteSwap(ctx->in, 16);
 130         MD5Transform(ctx->buf, ctx->in);
 131         p = (md5byte *)ctx->in;
 132         count = 56;
 133     }
 134
 135     memset(p, 0, count);
 136     byteSwap(ctx->in, 14);
 137
 138     /* Append length in bits and transform */
 139     ctx->in[14] = ctx->bytes[0] << 3;
 140     ctx->in[15] = ctx->bytes[1] << 3 | ctx->bytes[0] >> 29;
 141     MD5Transform(ctx->buf, ctx->in);
 142
 143     byteSwap(ctx->buf, 4);
 144     memcpy(digest, ctx->buf, 16);
 145     memset(ctx, 0, sizeof(*ctx)); /* In case it's sensitive */
 146 }
 147
 148 #ifndef ASM_MD5
 149
 150 /* The four core functions - F1 is optimized somewhat */
 151
 152 /* #define F1(x, y, z) (x & y | ~x & z) */
 153 #define F1(x, y, z) (z ^ (x & (y ^ z)))
 154 #define F2(x, y, z) F1(z, x, y)
 155 #define F3(x, y, z) (x ^ y ^ z)
 156 #define F4(x, y, z) (y ^ (x | ~z))
 157
 158 /* This is the central step in the MD5 algorithm. */
 159 #define MD5STEP(f,w,x,y,z,in,s) \
 160     (w += f(x,y,z) + in, w = (w<<s | w>>(32-s)) + x)
 161
 162 /*
 163  * The core of the MD5 algorithm, this alters an existing MD5 hash to
 164  * reflect the addition of 16 longwords of new data.  MD5Update blocks
 165  * the data and converts bytes into longwords for this routine.
 166  */
 167 void
 168 MD5Transform(UWORD32 buf[4], UWORD32 const in[16])
 169 {
 170     register UWORD32 a, b, c, d;
 171
 172     a = buf[0];
 173     b = buf[1];
 174     c = buf[2];
 175     d = buf[3];
 176
 177     MD5STEP(F1, a, b, c, d, in[0] + 0xd76aa478, 7);
 178     MD5STEP(F1, d, a, b, c, in[1] + 0xe8c7b756, 12);
 179     MD5STEP(F1, c, d, a, b, in[2] + 0x242070db, 17);
 180     MD5STEP(F1, b, c, d, a, in[3] + 0xc1bdceee, 22);
 181     MD5STEP(F1, a, b, c, d, in[4] + 0xf57c0faf, 7);
 182     MD5STEP(F1, d, a, b, c, in[5] + 0x4787c62a, 12);
 183     MD5STEP(F1, c, d, a, b, in[6] + 0xa8304613, 17);
 184     MD5STEP(F1, b, c, d, a, in[7] + 0xfd469501, 22);
 185     MD5STEP(F1, a, b, c, d, in[8] + 0x698098d8, 7);
 186     MD5STEP(F1, d, a, b, c, in[9] + 0x8b44f7af, 12);
 187     MD5STEP(F1, c, d, a, b, in[10] + 0xffff5bb1, 17);
 188     MD5STEP(F1, b, c, d, a, in[11] + 0x895cd7be, 22);
 189     MD5STEP(F1, a, b, c, d, in[12] + 0x6b901122, 7);
 190     MD5STEP(F1, d, a, b, c, in[13] + 0xfd987193, 12);
 191     MD5STEP(F1, c, d, a, b, in[14] + 0xa679438e, 17);
 192     MD5STEP(F1, b, c, d, a, in[15] + 0x49b40821, 22);
 193
 194     MD5STEP(F2, a, b, c, d, in[1] + 0xf61e2562, 5);
 195     MD5STEP(F2, d, a, b, c, in[6] + 0xc040b340, 9);
 196     MD5STEP(F2, c, d, a, b, in[11] + 0x265e5a51, 14);
 197     MD5STEP(F2, b, c, d, a, in[0] + 0xe9b6c7aa, 20);
 198     MD5STEP(F2, a, b, c, d, in[5] + 0xd62f105d, 5);
 199     MD5STEP(F2, d, a, b, c, in[10] + 0x02441453, 9);
 200     MD5STEP(F2, c, d, a, b, in[15] + 0xd8a1e681, 14);
 201     MD5STEP(F2, b, c, d, a, in[4] + 0xe7d3fbc8, 20);
 202     MD5STEP(F2, a, b, c, d, in[9] + 0x21e1cde6, 5);
 203     MD5STEP(F2, d, a, b, c, in[14] + 0xc33707d6, 9);
 204     MD5STEP(F2, c, d, a, b, in[3] + 0xf4d50d87, 14);
 205     MD5STEP(F2, b, c, d, a, in[8] + 0x455a14ed, 20);
 206     MD5STEP(F2, a, b, c, d, in[13] + 0xa9e3e905, 5);
 207     MD5STEP(F2, d, a, b, c, in[2] + 0xfcefa3f8, 9);
 208     MD5STEP(F2, c, d, a, b, in[7] + 0x676f02d9, 14);
 209     MD5STEP(F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);
 210
 211     MD5STEP(F3, a, b, c, d, in[5] + 0xfffa3942, 4);
 212     MD5STEP(F3, d, a, b, c, in[8] + 0x8771f681, 11);
 213     MD5STEP(F3, c, d, a, b, in[11] + 0x6d9d6122, 16);
 214     MD5STEP(F3, b, c, d, a, in[14] + 0xfde5380c, 23);
 215     MD5STEP(F3, a, b, c, d, in[1] + 0xa4beea44, 4);
 216     MD5STEP(F3, d, a, b, c, in[4] + 0x4bdecfa9, 11);
 217     MD5STEP(F3, c, d, a, b, in[7] + 0xf6bb4b60, 16);
 218     MD5STEP(F3, b, c, d, a, in[10] + 0xbebfbc70, 23);
 219     MD5STEP(F3, a, b, c, d, in[13] + 0x289b7ec6, 4);
 220     MD5STEP(F3, d, a, b, c, in[0] + 0xeaa127fa, 11);
 221     MD5STEP(F3, c, d, a, b, in[3] + 0xd4ef3085, 16);
 222     MD5STEP(F3, b, c, d, a, in[6] + 0x04881d05, 23);
 223     MD5STEP(F3, a, b, c, d, in[9] + 0xd9d4d039, 4);
 224     MD5STEP(F3, d, a, b, c, in[12] + 0xe6db99e5, 11);
 225     MD5STEP(F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);
 226     MD5STEP(F3, b, c, d, a, in[2] + 0xc4ac5665, 23);
 227
 228     MD5STEP(F4, a, b, c, d, in[0] + 0xf4292244, 6);
 229     MD5STEP(F4, d, a, b, c, in[7] + 0x432aff97, 10);
 230     MD5STEP(F4, c, d, a, b, in[14] + 0xab9423a7, 15);
 231     MD5STEP(F4, b, c, d, a, in[5] + 0xfc93a039, 21);
 232     MD5STEP(F4, a, b, c, d, in[12] + 0x655b59c3, 6);
 233     MD5STEP(F4, d, a, b, c, in[3] + 0x8f0ccc92, 10);
 234     MD5STEP(F4, c, d, a, b, in[10] + 0xffeff47d, 15);
 235     MD5STEP(F4, b, c, d, a, in[1] + 0x85845dd1, 21);
 236     MD5STEP(F4, a, b, c, d, in[8] + 0x6fa87e4f, 6);
 237     MD5STEP(F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);
 238     MD5STEP(F4, c, d, a, b, in[6] + 0xa3014314, 15);
 239     MD5STEP(F4, b, c, d, a, in[13] + 0x4e0811a1, 21);
 240     MD5STEP(F4, a, b, c, d, in[4] + 0xf7537e82, 6);
 241     MD5STEP(F4, d, a, b, c, in[11] + 0xbd3af235, 10);
 242     MD5STEP(F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15);
 243     MD5STEP(F4, b, c, d, a, in[9] + 0xeb86d391, 21);
 244
 245     buf[0] += a;
 246     buf[1] += b;
 247     buf[2] += c;
 248     buf[3] += d;
 249 }
 250
 251 #endif