md5.c

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00001 /*
00002  * This code implements the MD5 message-digest algorithm.
00003  * The algorithm is due to Ron Rivest.  This code was
00004  * written by Colin Plumb in 1993, no copyright is claimed.
00005  * This code is in the public domain; do with it what you wish.
00006  *
00007  * Equivalent code is available from RSA Data Security, Inc.
00008  * This code has been tested against that, and is equivalent,
00009  * except that you don't need to include two pages of legalese
00010  * with every copy.
00011  *
00012  * To compute the message digest of a chunk of bytes, declare an
00013  * MD5Context structure, pass it to MD5Init, call MD5Update as
00014  * needed on buffers full of bytes, and then call MD5Final, which
00015  * will fill a supplied 16-byte array with the digest.
00016  */
00017 
00018 /* Brutally hacked by John Walker back from ANSI C to K&R (no
00019    prototypes) to maintain the tradition that Netfone will compile
00020    with Sun's original "cc". */
00021 
00022 #include "md5.h"
00023 
00024 
00025 #ifndef HIGHFIRST
00026 #define byteReverse(buf, len)   /* Nothing */
00027 #else
00028 /*
00029  * Note: this code is harmless on little-endian machines.
00030  */
00031 static void 
00032 byteReverse(unsigned char *buf,
00033             unsigned longs)
00034 {
00035     uint32_t t;
00036     do {
00037         t = (uint32_t) ((unsigned) buf[3] << 8 | buf[2]) << 16 |
00038             ((unsigned) buf[1] << 8 | buf[0]);
00039         *(uint32_t *) buf = t;
00040         buf += 4;
00041     } while (--longs);
00042 }
00043 #endif
00044 
00045 
00046 /* The four core functions - F1 is optimized somewhat */
00047 
00048 /* #define F1(x, y, z) (x & y | ~x & z) */
00049 #define F1(x, y, z) (z ^ (x & (y ^ z)))
00050 #define F2(x, y, z) F1(z, x, y)
00051 #define F3(x, y, z) (x ^ y ^ z)
00052 #define F4(x, y, z) (y ^ (x | ~z))
00053 
00054 /* This is the central step in the MD5 algorithm. */
00055 #define MD5STEP(f, w, x, y, z, data, s) \
00056         ( w += f(x, y, z) + data,  w = w<<s | w>>(32-s),  w += x )
00057 
00058 /*
00059  * The core of the MD5 algorithm, this alters an existing MD5 hash to
00060  * reflect the addition of 16 longwords of new data.  MD5Update blocks
00061  * the data and converts bytes into longwords for this routine.
00062  */
00063 static void 
00064 MD5Transform(uint32_t buf[4],
00065              uint32_t in[16])
00066 {
00067   uint32_t a, b, c, d;
00068 
00069     a = buf[0];
00070     b = buf[1];
00071     c = buf[2];
00072     d = buf[3];
00073 
00074     MD5STEP(F1, a, b, c, d, in[0] + 0xd76aa478, 7);
00075     MD5STEP(F1, d, a, b, c, in[1] + 0xe8c7b756, 12);
00076     MD5STEP(F1, c, d, a, b, in[2] + 0x242070db, 17);
00077     MD5STEP(F1, b, c, d, a, in[3] + 0xc1bdceee, 22);
00078     MD5STEP(F1, a, b, c, d, in[4] + 0xf57c0faf, 7);
00079     MD5STEP(F1, d, a, b, c, in[5] + 0x4787c62a, 12);
00080     MD5STEP(F1, c, d, a, b, in[6] + 0xa8304613, 17);
00081     MD5STEP(F1, b, c, d, a, in[7] + 0xfd469501, 22);
00082     MD5STEP(F1, a, b, c, d, in[8] + 0x698098d8, 7);
00083     MD5STEP(F1, d, a, b, c, in[9] + 0x8b44f7af, 12);
00084     MD5STEP(F1, c, d, a, b, in[10] + 0xffff5bb1, 17);
00085     MD5STEP(F1, b, c, d, a, in[11] + 0x895cd7be, 22);
00086     MD5STEP(F1, a, b, c, d, in[12] + 0x6b901122, 7);
00087     MD5STEP(F1, d, a, b, c, in[13] + 0xfd987193, 12);
00088     MD5STEP(F1, c, d, a, b, in[14] + 0xa679438e, 17);
00089     MD5STEP(F1, b, c, d, a, in[15] + 0x49b40821, 22);
00090 
00091     MD5STEP(F2, a, b, c, d, in[1] + 0xf61e2562, 5);
00092     MD5STEP(F2, d, a, b, c, in[6] + 0xc040b340, 9);
00093     MD5STEP(F2, c, d, a, b, in[11] + 0x265e5a51, 14);
00094     MD5STEP(F2, b, c, d, a, in[0] + 0xe9b6c7aa, 20);
00095     MD5STEP(F2, a, b, c, d, in[5] + 0xd62f105d, 5);
00096     MD5STEP(F2, d, a, b, c, in[10] + 0x02441453, 9);
00097     MD5STEP(F2, c, d, a, b, in[15] + 0xd8a1e681, 14);
00098     MD5STEP(F2, b, c, d, a, in[4] + 0xe7d3fbc8, 20);
00099     MD5STEP(F2, a, b, c, d, in[9] + 0x21e1cde6, 5);
00100     MD5STEP(F2, d, a, b, c, in[14] + 0xc33707d6, 9);
00101     MD5STEP(F2, c, d, a, b, in[3] + 0xf4d50d87, 14);
00102     MD5STEP(F2, b, c, d, a, in[8] + 0x455a14ed, 20);
00103     MD5STEP(F2, a, b, c, d, in[13] + 0xa9e3e905, 5);
00104     MD5STEP(F2, d, a, b, c, in[2] + 0xfcefa3f8, 9);
00105     MD5STEP(F2, c, d, a, b, in[7] + 0x676f02d9, 14);
00106     MD5STEP(F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);
00107 
00108     MD5STEP(F3, a, b, c, d, in[5] + 0xfffa3942, 4);
00109     MD5STEP(F3, d, a, b, c, in[8] + 0x8771f681, 11);
00110     MD5STEP(F3, c, d, a, b, in[11] + 0x6d9d6122, 16);
00111     MD5STEP(F3, b, c, d, a, in[14] + 0xfde5380c, 23);
00112     MD5STEP(F3, a, b, c, d, in[1] + 0xa4beea44, 4);
00113     MD5STEP(F3, d, a, b, c, in[4] + 0x4bdecfa9, 11);
00114     MD5STEP(F3, c, d, a, b, in[7] + 0xf6bb4b60, 16);
00115     MD5STEP(F3, b, c, d, a, in[10] + 0xbebfbc70, 23);
00116     MD5STEP(F3, a, b, c, d, in[13] + 0x289b7ec6, 4);
00117     MD5STEP(F3, d, a, b, c, in[0] + 0xeaa127fa, 11);
00118     MD5STEP(F3, c, d, a, b, in[3] + 0xd4ef3085, 16);
00119     MD5STEP(F3, b, c, d, a, in[6] + 0x04881d05, 23);
00120     MD5STEP(F3, a, b, c, d, in[9] + 0xd9d4d039, 4);
00121     MD5STEP(F3, d, a, b, c, in[12] + 0xe6db99e5, 11);
00122     MD5STEP(F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);
00123     MD5STEP(F3, b, c, d, a, in[2] + 0xc4ac5665, 23);
00124 
00125     MD5STEP(F4, a, b, c, d, in[0] + 0xf4292244, 6);
00126     MD5STEP(F4, d, a, b, c, in[7] + 0x432aff97, 10);
00127     MD5STEP(F4, c, d, a, b, in[14] + 0xab9423a7, 15);
00128     MD5STEP(F4, b, c, d, a, in[5] + 0xfc93a039, 21);
00129     MD5STEP(F4, a, b, c, d, in[12] + 0x655b59c3, 6);
00130     MD5STEP(F4, d, a, b, c, in[3] + 0x8f0ccc92, 10);
00131     MD5STEP(F4, c, d, a, b, in[10] + 0xffeff47d, 15);
00132     MD5STEP(F4, b, c, d, a, in[1] + 0x85845dd1, 21);
00133     MD5STEP(F4, a, b, c, d, in[8] + 0x6fa87e4f, 6);
00134     MD5STEP(F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);
00135     MD5STEP(F4, c, d, a, b, in[6] + 0xa3014314, 15);
00136     MD5STEP(F4, b, c, d, a, in[13] + 0x4e0811a1, 21);
00137     MD5STEP(F4, a, b, c, d, in[4] + 0xf7537e82, 6);
00138     MD5STEP(F4, d, a, b, c, in[11] + 0xbd3af235, 10);
00139     MD5STEP(F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15);
00140     MD5STEP(F4, b, c, d, a, in[9] + 0xeb86d391, 21);
00141 
00142     buf[0] += a;
00143     buf[1] += b;
00144     buf[2] += c;
00145     buf[3] += d;
00146 }
00147 
00148 
00149 /*
00150  * Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
00151  * initialization constants.
00152  */
00153 void
00154 MD5Init(struct MD5Context *ctx)
00155 {
00156     ctx->buf[0] = 0x67452301;
00157     ctx->buf[1] = 0xefcdab89;
00158     ctx->buf[2] = 0x98badcfe;
00159     ctx->buf[3] = 0x10325476;
00160 
00161     ctx->bits[0] = 0;
00162     ctx->bits[1] = 0;
00163 }
00164 
00165 /*
00166  * Update context to reflect the concatenation of another buffer full
00167  * of bytes.
00168  */
00169 void
00170 MD5Update(struct MD5Context *ctx,
00171           const void *data,
00172           unsigned len)
00173 {
00174     const unsigned char *buf = data;
00175     uint32_t t;
00176 
00177     /* Update bitcount */
00178 
00179     t = ctx->bits[0];
00180     if ((ctx->bits[0] = t + ((uint32_t) len << 3)) < t)
00181         ctx->bits[1]++;         /* Carry from low to high */
00182     ctx->bits[1] += len >> 29;
00183 
00184     t = (t >> 3) & 0x3f;        /* Bytes already in shsInfo->data */
00185 
00186     /* Handle any leading odd-sized chunks */
00187 
00188     if (t) {
00189         unsigned char *p = (unsigned char *) ctx->in + t;
00190 
00191         t = 64 - t;
00192         if (len < t) {
00193             memcpy(p, buf, len);
00194             return;
00195         }
00196         memcpy(p, buf, t);
00197         byteReverse(ctx->in, 16);
00198         MD5Transform(ctx->buf, (uint32_t *) ctx->in);
00199         buf += t;
00200         len -= t;
00201     }
00202     /* Process data in 64-byte chunks */
00203 
00204     while (len >= 64) {
00205         memcpy(ctx->in, buf, 64);
00206         byteReverse(ctx->in, 16);
00207         MD5Transform(ctx->buf, (uint32_t *) ctx->in);
00208         buf += 64;
00209         len -= 64;
00210     }
00211 
00212     /* Handle any remaining bytes of data. */
00213 
00214     memcpy(ctx->in, buf, len);
00215 }
00216 
00217 /*
00218  * Final wrapup - pad to 64-byte boundary with the bit pattern 
00219  * 1 0* (64-bit count of bits processed, MSB-first)
00220  */
00221 void 
00222 MD5Final(unsigned char digest[16],
00223          struct MD5Context *ctx)
00224 {
00225   unsigned count;
00226   unsigned char *p;
00227 
00228   /* Compute number of bytes mod 64 */
00229   count = (ctx->bits[0] >> 3) & 0x3F;
00230   
00231   /* Set the first char of padding to 0x80.  This is safe since there is
00232      always at least one byte free */
00233   p = ctx->in + count;
00234   *p++ = 0x80;
00235   
00236   /* Bytes of padding needed to make 64 bytes */
00237   count = 64 - 1 - count;
00238   
00239   /* Pad out to 56 mod 64 */
00240   if (count < 8) 
00241     {
00242       /* Two lots of padding:  Pad the first block to 64 bytes */
00243       memset(p, 0, count);
00244       byteReverse(ctx->in, 16);
00245       MD5Transform(ctx->buf, (uint32_t *) ctx->in);
00246       
00247       /* Now fill the next block with 56 bytes */
00248       memset(ctx->in, 0, 56);
00249     } 
00250   else 
00251     {
00252       /* Pad block to 56 bytes */
00253       memset(p, 0, count - 8);
00254     }
00255   byteReverse(ctx->in, 14);
00256   
00257   /* Append length in bits and transform */
00258   ((uint32_t *) ctx->in)[14] = ctx->bits[0];
00259   ((uint32_t *) ctx->in)[15] = ctx->bits[1];
00260   
00261   MD5Transform(ctx->buf, (uint32_t *) ctx->in);
00262   byteReverse((unsigned char *) ctx->buf, 4);
00263   memcpy(digest, ctx->buf, 16);
00264   memset(ctx, 0, sizeof(struct MD5Context));        /* In case it's sensitive */
00265 }
00266 
00267 /* end of md5.c */

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