md5.c

/* Copyright (c) 2013, Robert Clausecker
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE. */

#include <limits.h>
#include <string.h>
#include "finalize.h"
#include "md5.h"

const struct md5_state md5_init =
	{ 0, { 0x67452301, 0xefcdab89, 0x98badcfe, 0x10325476 } };

/* shift parameters */
static const char shiftp[64] = {
	7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22,
	5,  9, 14, 20, 5,  9, 14, 20, 5,  9, 14, 20, 5,  9, 14, 20,
	4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23,
	6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21,
};

/* MD5 constants. Automatically generated by mksintab */
static const uint32_t md5const[64] = {
	0xd76aa478, 0xe8c7b756, 0x242070db, 0xc1bdceee,
	0xf57c0faf, 0x4787c62a, 0xa8304613, 0xfd469501,
	0x698098d8, 0x8b44f7af, 0xffff5bb1, 0x895cd7be,
	0x6b901122, 0xfd987193, 0xa679438e, 0x49b40821,
	0xf61e2562, 0xc040b340, 0x265e5a51, 0xe9b6c7aa,
	0xd62f105d, 0x02441453, 0xd8a1e681, 0xe7d3fbc8,
	0x21e1cde6, 0xc33707d6, 0xf4d50d87, 0x455a14ed,
	0xa9e3e905, 0xfcefa3f8, 0x676f02d9, 0x8d2a4c8a,
	0xfffa3942, 0x8771f681, 0x6d9d6122, 0xfde5380c,
	0xa4beea44, 0x4bdecfa9, 0xf6bb4b60, 0xbebfbc70,
	0x289b7ec6, 0xeaa127fa, 0xd4ef3085, 0x04881d05,
	0xd9d4d039, 0xe6db99e5, 0x1fa27cf8, 0xc4ac5665,
	0xf4292244, 0x432aff97, 0xab9423a7, 0xfc93a039,
	0x655b59c3, 0x8f0ccc92, 0xffeff47d, 0x85845dd1,
	0x6fa87e4f, 0xfe2ce6e0, 0xa3014314, 0x4e0811a1,
	0xf7537e82, 0xbd3af235, 0x2ad7d2bb, 0xeb86d391,
};

#define ROL(n, m) ((n) << (m) | (n) >> (32 - (m)))

extern void md5_block(union digest_state *u, const uint8_t *p) {
	struct md5_state *s = (struct md5_state*)u;

	int i, g;
	uint32_t a = s->h[0], b = s->h[1], c = s->h[2], d = s->h[3], f, t, x, y;
	const uint8_t *po;

	s->n++;

	for (i = 0; i < 64; i++) {
		if (i < 16) {
			f = b&c | ~b&d;
			g = i;
		} else if (i < 32) {
			f = d&b | ~d&c;
			g = 5*i + 1;
		} else if (i < 48) {
			f = b ^ c ^ d;
			g = 3*i + 5;
		} else {
			f = c ^ (b | ~d);
			g = 7*i;
		}

		t = d;
		d = c;
		c = b;
		/* compiler doesn't detect rotation when this is less explicit */
		po = p + sizeof(uint32_t)*(g&0xf);
		x = a + f + md5const[i];
		x += *po | *(po+1) << 8 | *(po+2) << 16 | *(po+3) << 24;
		y = shiftp[i];
		b += ROL(x, y);
		a = t;
	}

	s->h[0] += a;
	s->h[1] += b;
	s->h[2] += c;
	s->h[3] += d;
}

/* expects that n < 64. Overwrites p. */
extern void md5_final(union digest_state *u, uint8_t *p, size_t n, uint8_t *d) {
	finalize(u, p, n, d, MD5_DIGESTLEN, BIG, md5_block);
}