memzap

replay memory writes
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md5.c (7987B)


      1 /*	$OpenBSD: md5.c,v 1.2 2011/01/11 15:42:05 deraadt Exp $	*/
      2 
      3 /*
      4  * This code implements the MD5 message-digest algorithm.
      5  * The algorithm is due to Ron Rivest.	This code was
      6  * written by Colin Plumb in 1993, no copyright is claimed.
      7  * This code is in the public domain; do with it what you wish.
      8  *
      9  * Equivalent code is available from RSA Data Security, Inc.
     10  * This code has been tested against that, and is equivalent,
     11  * except that you don't need to include two pages of legalese
     12  * with every copy.
     13  *
     14  * To compute the message digest of a chunk of bytes, declare an
     15  * MD5Context structure, pass it to MD5Init, call MD5Update as
     16  * needed on buffers full of bytes, and then call MD5Final, which
     17  * will fill a supplied 16-byte array with the digest.
     18  */
     19 
     20 #include <stdio.h>
     21 #include <strings.h>
     22 #include <stdint.h>
     23 
     24 #include "md5.h"
     25 
     26 #define PUT_64BIT_LE(cp, value) do {		\
     27 		(cp)[7] = (value) >> 56;	\
     28 		(cp)[6] = (value) >> 48;	\
     29 		(cp)[5] = (value) >> 40;	\
     30 		(cp)[4] = (value) >> 32;	\
     31 		(cp)[3] = (value) >> 24;	\
     32 		(cp)[2] = (value) >> 16;	\
     33 		(cp)[1] = (value) >> 8;		\
     34 		(cp)[0] = (value); } while (0)
     35 
     36 #define PUT_32BIT_LE(cp, value) do {		\
     37 		(cp)[3] = (value) >> 24;	\
     38 		(cp)[2] = (value) >> 16;	\
     39 		(cp)[1] = (value) >> 8;		\
     40 		(cp)[0] = (value); } while (0)
     41 
     42 static uint8_t PADDING[MD5_BLOCK_LENGTH] = {
     43 	0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
     44 	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
     45 	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
     46 };
     47 
     48 /*
     49  * Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
     50  * initialization constants.
     51  */
     52 void
     53 MD5Init(MD5_CTX *ctx)
     54 {
     55 	ctx->count = 0;
     56 	ctx->state[0] = 0x67452301;
     57 	ctx->state[1] = 0xefcdab89;
     58 	ctx->state[2] = 0x98badcfe;
     59 	ctx->state[3] = 0x10325476;
     60 }
     61 
     62 /*
     63  * Update context to reflect the concatenation of another buffer full
     64  * of bytes.
     65  */
     66 void
     67 MD5Update(MD5_CTX *ctx, const unsigned char *input, size_t len)
     68 {
     69 	size_t have, need;
     70 
     71 	/* Check how many bytes we already have and how many more we need. */
     72 	have = (size_t)((ctx->count >> 3) & (MD5_BLOCK_LENGTH - 1));
     73 	need = MD5_BLOCK_LENGTH - have;
     74 
     75 	/* Update bitcount */
     76 	ctx->count += (uint64_t)len << 3;
     77 
     78 	if (len >= need) {
     79 		if (have != 0) {
     80 			bcopy(input, ctx->buffer + have, need);
     81 			MD5Transform(ctx->state, ctx->buffer);
     82 			input += need;
     83 			len -= need;
     84 			have = 0;
     85 		}
     86 
     87 		/* Process data in MD5_BLOCK_LENGTH-byte chunks. */
     88 		while (len >= MD5_BLOCK_LENGTH) {
     89 			MD5Transform(ctx->state, input);
     90 			input += MD5_BLOCK_LENGTH;
     91 			len -= MD5_BLOCK_LENGTH;
     92 		}
     93 	}
     94 
     95 	/* Handle any remaining bytes of data. */
     96 	if (len != 0)
     97 		bcopy(input, ctx->buffer + have, len);
     98 }
     99 
    100 /* explicit_bzero - don't let the compiler optimize away bzero */
    101 static void
    102 explicit_bzero(void *p, size_t n)
    103 {
    104 	bzero(p, n);
    105 }
    106 
    107 /*
    108  * Final wrapup - pad to 64-byte boundary with the bit pattern
    109  * 1 0* (64-bit count of bits processed, MSB-first)
    110  */
    111 void
    112 MD5Final(unsigned char digest[MD5_DIGEST_LENGTH], MD5_CTX *ctx)
    113 {
    114 	uint8_t count[8];
    115 	size_t padlen;
    116 	int i;
    117 
    118 	/* Convert count to 8 bytes in little endian order. */
    119 	PUT_64BIT_LE(count, ctx->count);
    120 
    121 	/* Pad out to 56 mod 64. */
    122 	padlen = MD5_BLOCK_LENGTH -
    123 		((ctx->count >> 3) & (MD5_BLOCK_LENGTH - 1));
    124 	if (padlen < 1 + 8)
    125 		padlen += MD5_BLOCK_LENGTH;
    126 	MD5Update(ctx, PADDING, padlen - 8); /* padlen - 8 <= 64 */
    127 	MD5Update(ctx, count, 8);
    128 
    129 	if (digest != NULL) {
    130 		for (i = 0; i < 4; i++)
    131 			PUT_32BIT_LE(digest + i * 4, ctx->state[i]);
    132 	}
    133 	explicit_bzero(ctx, sizeof(*ctx)); /* in case it's sensitive */
    134 }
    135 
    136 /* The four core functions - F1 is optimized somewhat */
    137 
    138 /* #define F1(x, y, z) (x & y | ~x & z) */
    139 #define F1(x, y, z) (z ^ (x & (y ^ z)))
    140 #define F2(x, y, z) F1(z, x, y)
    141 #define F3(x, y, z) (x ^ y ^ z)
    142 #define F4(x, y, z) (y ^ (x | ~z))
    143 
    144 /* This is the central step in the MD5 algorithm. */
    145 #define MD5STEP(f, w, x, y, z, data, s) \
    146 	( w += f(x, y, z) + data,  w = w<<s | w>>(32-s),  w += x )
    147 
    148 /*
    149  * The core of the MD5 algorithm, this alters an existing MD5 hash to
    150  * reflect the addition of 16 longwords of new data.  MD5Update blocks
    151  * the data and converts bytes into longwords for this routine.
    152  */
    153 void
    154 MD5Transform(uint32_t state[4], const uint8_t block[MD5_BLOCK_LENGTH])
    155 {
    156 	uint32_t a, b, c, d, in[MD5_BLOCK_LENGTH / 4];
    157 
    158 #if BYTE_ORDER == LITTLE_ENDIAN
    159 	bcopy(block, in, sizeof(in));
    160 #else
    161 	for (a = 0; a < MD5_BLOCK_LENGTH / 4; a++) {
    162 		in[a] = (uint32_t)(
    163 			(uint32_t)(block[a * 4 + 0]) |
    164 			(uint32_t)(block[a * 4 + 1]) <<  8 |
    165 			(uint32_t)(block[a * 4 + 2]) << 16 |
    166 			(uint32_t)(block[a * 4 + 3]) << 24);
    167 	}
    168 #endif
    169 
    170 	a = state[0];
    171 	b = state[1];
    172 	c = state[2];
    173 	d = state[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 	state[0] += a;
    244 	state[1] += b;
    245 	state[2] += c;
    246 	state[3] += d;
    247 }