1/*
2 * dhcpcd - DHCP client daemon
3 * Copyright (c) 2006-2015 Roy Marples <roy@marples.name>
4 * All rights reserved
5
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28#include <inttypes.h>
29#include <string.h>
30
31#include "crypt.h"
32
33#include "../config.h"
34#ifdef HAVE_MD5_H
35#  ifndef DEPGEN
36#    include <md5.h>
37#  endif
38#else
39#  include "md5.h"
40#endif
41
42#define HMAC_PAD_LEN	64
43#define IPAD		0x36
44#define OPAD		0x5C
45
46/* hmac_md5 as per RFC3118 */
47void
48hmac_md5(const uint8_t *text, size_t text_len,
49    const uint8_t *key, size_t key_len,
50    uint8_t *digest)
51{
52	uint8_t k_ipad[HMAC_PAD_LEN], k_opad[HMAC_PAD_LEN];
53	uint8_t tk[MD5_DIGEST_LENGTH];
54	int i;
55	MD5_CTX context;
56
57	/* Ensure key is no bigger than HMAC_PAD_LEN */
58	if (key_len > HMAC_PAD_LEN) {
59		MD5Init(&context);
60		MD5Update(&context, key, (unsigned int)key_len);
61		MD5Final(tk, &context);
62		key = tk;
63		key_len = MD5_DIGEST_LENGTH;
64	}
65
66	/* store key in pads */
67	memcpy(k_ipad, key, key_len);
68	memcpy(k_opad, key, key_len);
69	memset(k_ipad + key_len, 0, sizeof(k_ipad) - key_len);
70	memset(k_opad + key_len, 0, sizeof(k_opad) - key_len);
71
72	/* XOR key with ipad and opad values */
73	for (i = 0; i < HMAC_PAD_LEN; i++) {
74		k_ipad[i] ^= IPAD;
75		k_opad[i] ^= OPAD;
76	}
77
78	/* inner MD5 */
79	MD5Init(&context);
80	MD5Update(&context, k_ipad, HMAC_PAD_LEN);
81	MD5Update(&context, text, (unsigned int)text_len);
82	MD5Final(digest, &context);
83
84	/* outer MD5 */
85	MD5Init(&context);
86	MD5Update(&context, k_opad, HMAC_PAD_LEN);
87	MD5Update(&context, digest, MD5_DIGEST_LENGTH);
88	MD5Final(digest, &context);
89}
90