Sat Aug 6 00:39:30 2011

Asterisk developer's documentation


md5.c

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00001 
00002 /*!\file
00003 \brief     MD5 checksum routines used for authentication.  Not covered by GPL, but
00004    in the public domain as per the copyright below */
00005 
00006 /*
00007  * This code implements the MD5 message-digest algorithm.
00008  * The algorithm is due to Ron Rivest.  This code was
00009  * written by Colin Plumb in 1993, no copyright is claimed.
00010  * This code is in the public domain; do with it what you wish.
00011  *
00012  * Equivalent code is available from RSA Data Security, Inc.
00013  * This code has been tested against that, and is equivalent,
00014  * except that you don't need to include two pages of legalese
00015  * with every copy.
00016  *
00017  * To compute the message digest of a chunk of bytes, declare an
00018  * MD5Context structure, pass it to MD5Init, call MD5Update as
00019  * needed on buffers full of bytes, and then call MD5Final, which
00020  * will fill a supplied 16-byte array with the digest.
00021  */
00022 
00023 #include "asterisk.h"
00024 
00025 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 40722 $")
00026 
00027 #include <string.h>     /* for memcpy() */
00028 
00029 #include "asterisk/endian.h"
00030 #include "asterisk/md5.h"
00031 
00032 # if __BYTE_ORDER == __BIG_ENDIAN
00033 #  define HIGHFIRST 1
00034 # endif
00035 #ifndef HIGHFIRST
00036 #define byteReverse(buf, len) /* Nothing */
00037 #else
00038 void byteReverse(unsigned char *buf, unsigned longs);
00039 
00040 #ifndef ASM_MD5
00041 /*
00042  * Note: this code is harmless on little-endian machines.
00043  */
00044 void byteReverse(unsigned char *buf, unsigned longs)
00045 {
00046    uint32_t t;
00047    do {
00048       t = (uint32_t) ((unsigned) buf[3] << 8 | buf[2]) << 16 |
00049          ((unsigned) buf[1] << 8 | buf[0]);
00050       *(uint32_t *) buf = t;
00051       buf += 4;
00052    } while (--longs);
00053 }
00054 #endif
00055 #endif
00056 
00057 /*
00058  * Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
00059  * initialization constants.
00060  */
00061 void MD5Init(struct MD5Context *ctx)
00062 {
00063    ctx->buf[0] = 0x67452301;
00064    ctx->buf[1] = 0xefcdab89;
00065    ctx->buf[2] = 0x98badcfe;
00066    ctx->buf[3] = 0x10325476;
00067 
00068    ctx->bits[0] = 0;
00069    ctx->bits[1] = 0;
00070 }
00071 
00072 /*
00073  * Update context to reflect the concatenation of another buffer full
00074  * of bytes.
00075  */
00076 void MD5Update(struct MD5Context *ctx, unsigned char const *buf, unsigned len)
00077 {
00078    uint32_t t;
00079 
00080    /* Update bitcount */
00081 
00082    t = ctx->bits[0];
00083    if ((ctx->bits[0] = t + ((uint32_t) len << 3)) < t)
00084       ctx->bits[1]++;      /* Carry from low to high */
00085    ctx->bits[1] += len >> 29;
00086 
00087    t = (t >> 3) & 0x3f; /* Bytes already in shsInfo->data */
00088 
00089    /* Handle any leading odd-sized chunks */
00090 
00091    if (t) {
00092       unsigned char *p = (unsigned char *) ctx->in + t;
00093 
00094       t = 64 - t;
00095       if (len < t) {
00096          memcpy(p, buf, len);
00097          return;
00098       }
00099       memcpy(p, buf, t);
00100       byteReverse(ctx->in, 16);
00101       MD5Transform(ctx->buf, (uint32_t *) ctx->in);
00102       buf += t;
00103       len -= t;
00104    }
00105    /* Process data in 64-byte chunks */
00106 
00107    while (len >= 64) {
00108       memcpy(ctx->in, buf, 64);
00109       byteReverse(ctx->in, 16);
00110       MD5Transform(ctx->buf, (uint32_t *) ctx->in);
00111       buf += 64;
00112       len -= 64;
00113    }
00114 
00115    /* Handle any remaining bytes of data. */
00116 
00117    memcpy(ctx->in, buf, len);
00118 }
00119 
00120 /*
00121  * Final wrapup - pad to 64-byte boundary with the bit pattern 
00122  * 1 0* (64-bit count of bits processed, MSB-first)
00123  */
00124 void MD5Final(unsigned char digest[16], struct MD5Context *ctx)
00125 {
00126    unsigned count;
00127    unsigned char *p;
00128 
00129    /* Compute number of bytes mod 64 */
00130    count = (ctx->bits[0] >> 3) & 0x3F;
00131 
00132    /* Set the first char of padding to 0x80.  This is safe since there is
00133       always at least one byte free */
00134    p = ctx->in + count;
00135    *p++ = 0x80;
00136 
00137    /* Bytes of padding needed to make 64 bytes */
00138    count = 64 - 1 - count;
00139 
00140    /* Pad out to 56 mod 64 */
00141    if (count < 8) {
00142       /* Two lots of padding:  Pad the first block to 64 bytes */
00143       memset(p, 0, count);
00144       byteReverse(ctx->in, 16);
00145       MD5Transform(ctx->buf, (uint32_t *) ctx->in);
00146 
00147       /* Now fill the next block with 56 bytes */
00148       memset(ctx->in, 0, 56);
00149    } else {
00150       /* Pad block to 56 bytes */
00151       memset(p, 0, count - 8);
00152    }
00153    byteReverse(ctx->in, 14);
00154 
00155    /* Append length in bits and transform */
00156    ((uint32_t *) ctx->in)[14] = ctx->bits[0];
00157    ((uint32_t *) ctx->in)[15] = ctx->bits[1];
00158 
00159    MD5Transform(ctx->buf, (uint32_t *) ctx->in);
00160    byteReverse((unsigned char *) ctx->buf, 4);
00161    memcpy(digest, ctx->buf, 16);
00162    memset(ctx, 0, sizeof(ctx));  /* In case it's sensitive */
00163 }
00164 
00165 #ifndef ASM_MD5
00166 
00167 /* The four core functions - F1 is optimized somewhat */
00168 
00169 /* #define F1(x, y, z) (x & y | ~x & z) */
00170 #define F1(x, y, z) (z ^ (x & (y ^ z)))
00171 #define F2(x, y, z) F1(z, x, y)
00172 #define F3(x, y, z) (x ^ y ^ z)
00173 #define F4(x, y, z) (y ^ (x | ~z))
00174 
00175 /* This is the central step in the MD5 algorithm. */
00176 #define MD5STEP(f, w, x, y, z, data, s) \
00177    ( w += f(x, y, z) + data,  w = w<<s | w>>(32-s),  w += x )
00178 
00179 /*
00180  * The core of the MD5 algorithm, this alters an existing MD5 hash to
00181  * reflect the addition of 16 longwords of new data.  MD5Update blocks
00182  * the data and converts bytes into longwords for this routine.
00183  */
00184 void MD5Transform(uint32_t buf[4], uint32_t const in[16])
00185 {
00186    register uint32_t a, b, c, d;
00187 
00188    a = buf[0];
00189    b = buf[1];
00190    c = buf[2];
00191    d = buf[3];
00192 
00193    MD5STEP(F1, a, b, c, d, in[0] + 0xd76aa478, 7);
00194    MD5STEP(F1, d, a, b, c, in[1] + 0xe8c7b756, 12);
00195    MD5STEP(F1, c, d, a, b, in[2] + 0x242070db, 17);
00196    MD5STEP(F1, b, c, d, a, in[3] + 0xc1bdceee, 22);
00197    MD5STEP(F1, a, b, c, d, in[4] + 0xf57c0faf, 7);
00198    MD5STEP(F1, d, a, b, c, in[5] + 0x4787c62a, 12);
00199    MD5STEP(F1, c, d, a, b, in[6] + 0xa8304613, 17);
00200    MD5STEP(F1, b, c, d, a, in[7] + 0xfd469501, 22);
00201    MD5STEP(F1, a, b, c, d, in[8] + 0x698098d8, 7);
00202    MD5STEP(F1, d, a, b, c, in[9] + 0x8b44f7af, 12);
00203    MD5STEP(F1, c, d, a, b, in[10] + 0xffff5bb1, 17);
00204    MD5STEP(F1, b, c, d, a, in[11] + 0x895cd7be, 22);
00205    MD5STEP(F1, a, b, c, d, in[12] + 0x6b901122, 7);
00206    MD5STEP(F1, d, a, b, c, in[13] + 0xfd987193, 12);
00207    MD5STEP(F1, c, d, a, b, in[14] + 0xa679438e, 17);
00208    MD5STEP(F1, b, c, d, a, in[15] + 0x49b40821, 22);
00209 
00210    MD5STEP(F2, a, b, c, d, in[1] + 0xf61e2562, 5);
00211    MD5STEP(F2, d, a, b, c, in[6] + 0xc040b340, 9);
00212    MD5STEP(F2, c, d, a, b, in[11] + 0x265e5a51, 14);
00213    MD5STEP(F2, b, c, d, a, in[0] + 0xe9b6c7aa, 20);
00214    MD5STEP(F2, a, b, c, d, in[5] + 0xd62f105d, 5);
00215    MD5STEP(F2, d, a, b, c, in[10] + 0x02441453, 9);
00216    MD5STEP(F2, c, d, a, b, in[15] + 0xd8a1e681, 14);
00217    MD5STEP(F2, b, c, d, a, in[4] + 0xe7d3fbc8, 20);
00218    MD5STEP(F2, a, b, c, d, in[9] + 0x21e1cde6, 5);
00219    MD5STEP(F2, d, a, b, c, in[14] + 0xc33707d6, 9);
00220    MD5STEP(F2, c, d, a, b, in[3] + 0xf4d50d87, 14);
00221    MD5STEP(F2, b, c, d, a, in[8] + 0x455a14ed, 20);
00222    MD5STEP(F2, a, b, c, d, in[13] + 0xa9e3e905, 5);
00223    MD5STEP(F2, d, a, b, c, in[2] + 0xfcefa3f8, 9);
00224    MD5STEP(F2, c, d, a, b, in[7] + 0x676f02d9, 14);
00225    MD5STEP(F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);
00226 
00227    MD5STEP(F3, a, b, c, d, in[5] + 0xfffa3942, 4);
00228    MD5STEP(F3, d, a, b, c, in[8] + 0x8771f681, 11);
00229    MD5STEP(F3, c, d, a, b, in[11] + 0x6d9d6122, 16);
00230    MD5STEP(F3, b, c, d, a, in[14] + 0xfde5380c, 23);
00231    MD5STEP(F3, a, b, c, d, in[1] + 0xa4beea44, 4);
00232    MD5STEP(F3, d, a, b, c, in[4] + 0x4bdecfa9, 11);
00233    MD5STEP(F3, c, d, a, b, in[7] + 0xf6bb4b60, 16);
00234    MD5STEP(F3, b, c, d, a, in[10] + 0xbebfbc70, 23);
00235    MD5STEP(F3, a, b, c, d, in[13] + 0x289b7ec6, 4);
00236    MD5STEP(F3, d, a, b, c, in[0] + 0xeaa127fa, 11);
00237    MD5STEP(F3, c, d, a, b, in[3] + 0xd4ef3085, 16);
00238    MD5STEP(F3, b, c, d, a, in[6] + 0x04881d05, 23);
00239    MD5STEP(F3, a, b, c, d, in[9] + 0xd9d4d039, 4);
00240    MD5STEP(F3, d, a, b, c, in[12] + 0xe6db99e5, 11);
00241    MD5STEP(F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);
00242    MD5STEP(F3, b, c, d, a, in[2] + 0xc4ac5665, 23);
00243 
00244    MD5STEP(F4, a, b, c, d, in[0] + 0xf4292244, 6);
00245    MD5STEP(F4, d, a, b, c, in[7] + 0x432aff97, 10);
00246    MD5STEP(F4, c, d, a, b, in[14] + 0xab9423a7, 15);
00247    MD5STEP(F4, b, c, d, a, in[5] + 0xfc93a039, 21);
00248    MD5STEP(F4, a, b, c, d, in[12] + 0x655b59c3, 6);
00249    MD5STEP(F4, d, a, b, c, in[3] + 0x8f0ccc92, 10);
00250    MD5STEP(F4, c, d, a, b, in[10] + 0xffeff47d, 15);
00251    MD5STEP(F4, b, c, d, a, in[1] + 0x85845dd1, 21);
00252    MD5STEP(F4, a, b, c, d, in[8] + 0x6fa87e4f, 6);
00253    MD5STEP(F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);
00254    MD5STEP(F4, c, d, a, b, in[6] + 0xa3014314, 15);
00255    MD5STEP(F4, b, c, d, a, in[13] + 0x4e0811a1, 21);
00256    MD5STEP(F4, a, b, c, d, in[4] + 0xf7537e82, 6);
00257    MD5STEP(F4, d, a, b, c, in[11] + 0xbd3af235, 10);
00258    MD5STEP(F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15);
00259    MD5STEP(F4, b, c, d, a, in[9] + 0xeb86d391, 21);
00260 
00261    buf[0] += a;
00262    buf[1] += b;
00263    buf[2] += c;
00264    buf[3] += d;
00265 }
00266 
00267 #endif

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