Mon Mar 19 11:30:28 2012

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: 89333 $")
00026 
00027 #include "asterisk/endian.h"
00028 #include "asterisk/md5.h"
00029 
00030 # if __BYTE_ORDER == __BIG_ENDIAN
00031 #  define HIGHFIRST 1
00032 # endif
00033 #ifndef HIGHFIRST
00034 #define byteReverse(buf, len) /* Nothing */
00035 #else
00036 void byteReverse(unsigned char *buf, unsigned longs);
00037 
00038 #ifndef ASM_MD5
00039 /*
00040  * Note: this code is harmless on little-endian machines.
00041  */
00042 void byteReverse(unsigned char *buf, unsigned longs)
00043 {
00044    uint32_t t;
00045    do {
00046       t = (uint32_t) ((unsigned) buf[3] << 8 | buf[2]) << 16 |
00047          ((unsigned) buf[1] << 8 | buf[0]);
00048       *(uint32_t *) buf = t;
00049       buf += 4;
00050    } while (--longs);
00051 }
00052 #endif
00053 #endif
00054 
00055 /*
00056  * Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
00057  * initialization constants.
00058  */
00059 void MD5Init(struct MD5Context *ctx)
00060 {
00061    ctx->buf[0] = 0x67452301;
00062    ctx->buf[1] = 0xefcdab89;
00063    ctx->buf[2] = 0x98badcfe;
00064    ctx->buf[3] = 0x10325476;
00065 
00066    ctx->bits[0] = 0;
00067    ctx->bits[1] = 0;
00068 }
00069 
00070 /*
00071  * Update context to reflect the concatenation of another buffer full
00072  * of bytes.
00073  */
00074 void MD5Update(struct MD5Context *ctx, unsigned char const *buf, unsigned len)
00075 {
00076    uint32_t t;
00077 
00078    /* Update bitcount */
00079 
00080    t = ctx->bits[0];
00081    if ((ctx->bits[0] = t + ((uint32_t) len << 3)) < t)
00082       ctx->bits[1]++;      /* Carry from low to high */
00083    ctx->bits[1] += len >> 29;
00084 
00085    t = (t >> 3) & 0x3f; /* Bytes already in shsInfo->data */
00086 
00087    /* Handle any leading odd-sized chunks */
00088 
00089    if (t) {
00090       unsigned char *p = (unsigned char *) ctx->in + t;
00091 
00092       t = 64 - t;
00093       if (len < t) {
00094          memcpy(p, buf, len);
00095          return;
00096       }
00097       memcpy(p, buf, t);
00098       byteReverse(ctx->in, 16);
00099       MD5Transform(ctx->buf, (uint32_t *) ctx->in);
00100       buf += t;
00101       len -= t;
00102    }
00103    /* Process data in 64-byte chunks */
00104 
00105    while (len >= 64) {
00106       memcpy(ctx->in, buf, 64);
00107       byteReverse(ctx->in, 16);
00108       MD5Transform(ctx->buf, (uint32_t *) ctx->in);
00109       buf += 64;
00110       len -= 64;
00111    }
00112 
00113    /* Handle any remaining bytes of data. */
00114 
00115    memcpy(ctx->in, buf, len);
00116 }
00117 
00118 /*
00119  * Final wrapup - pad to 64-byte boundary with the bit pattern 
00120  * 1 0* (64-bit count of bits processed, MSB-first)
00121  */
00122 void MD5Final(unsigned char digest[16], struct MD5Context *ctx)
00123 {
00124    unsigned count;
00125    unsigned char *p;
00126 
00127    /* Compute number of bytes mod 64 */
00128    count = (ctx->bits[0] >> 3) & 0x3F;
00129 
00130    /* Set the first char of padding to 0x80.  This is safe since there is
00131       always at least one byte free */
00132    p = ctx->in + count;
00133    *p++ = 0x80;
00134 
00135    /* Bytes of padding needed to make 64 bytes */
00136    count = 64 - 1 - count;
00137 
00138    /* Pad out to 56 mod 64 */
00139    if (count < 8) {
00140       /* Two lots of padding:  Pad the first block to 64 bytes */
00141       memset(p, 0, count);
00142       byteReverse(ctx->in, 16);
00143       MD5Transform(ctx->buf, (uint32_t *) ctx->in);
00144 
00145       /* Now fill the next block with 56 bytes */
00146       memset(ctx->in, 0, 56);
00147    } else {
00148       /* Pad block to 56 bytes */
00149       memset(p, 0, count - 8);
00150    }
00151    byteReverse(ctx->in, 14);
00152 
00153    /* Append length in bits and transform */
00154    ((uint32_t *) ctx->in)[14] = ctx->bits[0];
00155    ((uint32_t *) ctx->in)[15] = ctx->bits[1];
00156 
00157    MD5Transform(ctx->buf, (uint32_t *) ctx->in);
00158    byteReverse((unsigned char *) ctx->buf, 4);
00159    memcpy(digest, ctx->buf, 16);
00160    memset(ctx, 0, sizeof(ctx));  /* In case it's sensitive */
00161 }
00162 
00163 #ifndef ASM_MD5
00164 
00165 /* The four core functions - F1 is optimized somewhat */
00166 
00167 /* #define F1(x, y, z) (x & y | ~x & z) */
00168 #define F1(x, y, z) (z ^ (x & (y ^ z)))
00169 #define F2(x, y, z) F1(z, x, y)
00170 #define F3(x, y, z) (x ^ y ^ z)
00171 #define F4(x, y, z) (y ^ (x | ~z))
00172 
00173 /* This is the central step in the MD5 algorithm. */
00174 #define MD5STEP(f, w, x, y, z, data, s) \
00175    ( w += f(x, y, z) + data,  w = w<<s | w>>(32-s),  w += x )
00176 
00177 /*
00178  * The core of the MD5 algorithm, this alters an existing MD5 hash to
00179  * reflect the addition of 16 longwords of new data.  MD5Update blocks
00180  * the data and converts bytes into longwords for this routine.
00181  */
00182 void MD5Transform(uint32_t buf[4], uint32_t const in[16])
00183 {
00184    register uint32_t a, b, c, d;
00185 
00186    a = buf[0];
00187    b = buf[1];
00188    c = buf[2];
00189    d = buf[3];
00190 
00191    MD5STEP(F1, a, b, c, d, in[0] + 0xd76aa478, 7);
00192    MD5STEP(F1, d, a, b, c, in[1] + 0xe8c7b756, 12);
00193    MD5STEP(F1, c, d, a, b, in[2] + 0x242070db, 17);
00194    MD5STEP(F1, b, c, d, a, in[3] + 0xc1bdceee, 22);
00195    MD5STEP(F1, a, b, c, d, in[4] + 0xf57c0faf, 7);
00196    MD5STEP(F1, d, a, b, c, in[5] + 0x4787c62a, 12);
00197    MD5STEP(F1, c, d, a, b, in[6] + 0xa8304613, 17);
00198    MD5STEP(F1, b, c, d, a, in[7] + 0xfd469501, 22);
00199    MD5STEP(F1, a, b, c, d, in[8] + 0x698098d8, 7);
00200    MD5STEP(F1, d, a, b, c, in[9] + 0x8b44f7af, 12);
00201    MD5STEP(F1, c, d, a, b, in[10] + 0xffff5bb1, 17);
00202    MD5STEP(F1, b, c, d, a, in[11] + 0x895cd7be, 22);
00203    MD5STEP(F1, a, b, c, d, in[12] + 0x6b901122, 7);
00204    MD5STEP(F1, d, a, b, c, in[13] + 0xfd987193, 12);
00205    MD5STEP(F1, c, d, a, b, in[14] + 0xa679438e, 17);
00206    MD5STEP(F1, b, c, d, a, in[15] + 0x49b40821, 22);
00207 
00208    MD5STEP(F2, a, b, c, d, in[1] + 0xf61e2562, 5);
00209    MD5STEP(F2, d, a, b, c, in[6] + 0xc040b340, 9);
00210    MD5STEP(F2, c, d, a, b, in[11] + 0x265e5a51, 14);
00211    MD5STEP(F2, b, c, d, a, in[0] + 0xe9b6c7aa, 20);
00212    MD5STEP(F2, a, b, c, d, in[5] + 0xd62f105d, 5);
00213    MD5STEP(F2, d, a, b, c, in[10] + 0x02441453, 9);
00214    MD5STEP(F2, c, d, a, b, in[15] + 0xd8a1e681, 14);
00215    MD5STEP(F2, b, c, d, a, in[4] + 0xe7d3fbc8, 20);
00216    MD5STEP(F2, a, b, c, d, in[9] + 0x21e1cde6, 5);
00217    MD5STEP(F2, d, a, b, c, in[14] + 0xc33707d6, 9);
00218    MD5STEP(F2, c, d, a, b, in[3] + 0xf4d50d87, 14);
00219    MD5STEP(F2, b, c, d, a, in[8] + 0x455a14ed, 20);
00220    MD5STEP(F2, a, b, c, d, in[13] + 0xa9e3e905, 5);
00221    MD5STEP(F2, d, a, b, c, in[2] + 0xfcefa3f8, 9);
00222    MD5STEP(F2, c, d, a, b, in[7] + 0x676f02d9, 14);
00223    MD5STEP(F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);
00224 
00225    MD5STEP(F3, a, b, c, d, in[5] + 0xfffa3942, 4);
00226    MD5STEP(F3, d, a, b, c, in[8] + 0x8771f681, 11);
00227    MD5STEP(F3, c, d, a, b, in[11] + 0x6d9d6122, 16);
00228    MD5STEP(F3, b, c, d, a, in[14] + 0xfde5380c, 23);
00229    MD5STEP(F3, a, b, c, d, in[1] + 0xa4beea44, 4);
00230    MD5STEP(F3, d, a, b, c, in[4] + 0x4bdecfa9, 11);
00231    MD5STEP(F3, c, d, a, b, in[7] + 0xf6bb4b60, 16);
00232    MD5STEP(F3, b, c, d, a, in[10] + 0xbebfbc70, 23);
00233    MD5STEP(F3, a, b, c, d, in[13] + 0x289b7ec6, 4);
00234    MD5STEP(F3, d, a, b, c, in[0] + 0xeaa127fa, 11);
00235    MD5STEP(F3, c, d, a, b, in[3] + 0xd4ef3085, 16);
00236    MD5STEP(F3, b, c, d, a, in[6] + 0x04881d05, 23);
00237    MD5STEP(F3, a, b, c, d, in[9] + 0xd9d4d039, 4);
00238    MD5STEP(F3, d, a, b, c, in[12] + 0xe6db99e5, 11);
00239    MD5STEP(F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);
00240    MD5STEP(F3, b, c, d, a, in[2] + 0xc4ac5665, 23);
00241 
00242    MD5STEP(F4, a, b, c, d, in[0] + 0xf4292244, 6);
00243    MD5STEP(F4, d, a, b, c, in[7] + 0x432aff97, 10);
00244    MD5STEP(F4, c, d, a, b, in[14] + 0xab9423a7, 15);
00245    MD5STEP(F4, b, c, d, a, in[5] + 0xfc93a039, 21);
00246    MD5STEP(F4, a, b, c, d, in[12] + 0x655b59c3, 6);
00247    MD5STEP(F4, d, a, b, c, in[3] + 0x8f0ccc92, 10);
00248    MD5STEP(F4, c, d, a, b, in[10] + 0xffeff47d, 15);
00249    MD5STEP(F4, b, c, d, a, in[1] + 0x85845dd1, 21);
00250    MD5STEP(F4, a, b, c, d, in[8] + 0x6fa87e4f, 6);
00251    MD5STEP(F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);
00252    MD5STEP(F4, c, d, a, b, in[6] + 0xa3014314, 15);
00253    MD5STEP(F4, b, c, d, a, in[13] + 0x4e0811a1, 21);
00254    MD5STEP(F4, a, b, c, d, in[4] + 0xf7537e82, 6);
00255    MD5STEP(F4, d, a, b, c, in[11] + 0xbd3af235, 10);
00256    MD5STEP(F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15);
00257    MD5STEP(F4, b, c, d, a, in[9] + 0xeb86d391, 21);
00258 
00259    buf[0] += a;
00260    buf[1] += b;
00261    buf[2] += c;
00262    buf[3] += d;
00263 }
00264 
00265 #endif

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