md5.c revision 8d520ff1dc2da35cdca849e982051b86468016d8 
1/*
2 * MD5 hash implementation and interface functions
3 * Copyright (c) 2003-2005, Jouni Malinen <j@w1.fi>
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
8 *
9 * Alternatively, this software may be distributed under the terms of BSD
10 * license.
11 *
12 * See README and COPYING for more details.
13 */
14
15#include "includes.h"
16
17#include "common.h"
18#include "md5.h"
19#include "crypto.h"
20
21
22/**
23 * hmac_md5_vector - HMAC-MD5 over data vector (RFC 2104)
24 * @key: Key for HMAC operations
25 * @key_len: Length of the key in bytes
26 * @num_elem: Number of elements in the data vector
27 * @addr: Pointers to the data areas
28 * @len: Lengths of the data blocks
29 * @mac: Buffer for the hash (16 bytes)
30 * Returns: 0 on success, -1 on failure
31 */
32int hmac_md5_vector(const u8 *key, size_t key_len, size_t num_elem,
33		    const u8 *addr[], const size_t *len, u8 *mac)
34{
35	u8 k_pad[64]; /* padding - key XORd with ipad/opad */
36	u8 tk[16];
37	const u8 *_addr[6];
38	size_t i, _len[6];
39
40	if (num_elem > 5) {
41		/*
42		 * Fixed limit on the number of fragments to avoid having to
43		 * allocate memory (which could fail).
44		 */
45		return -1;
46	}
47
48        /* if key is longer than 64 bytes reset it to key = MD5(key) */
49        if (key_len > 64) {
50		if (md5_vector(1, &key, &key_len, tk))
51			return -1;
52		key = tk;
53		key_len = 16;
54        }
55
56	/* the HMAC_MD5 transform looks like:
57	 *
58	 * MD5(K XOR opad, MD5(K XOR ipad, text))
59	 *
60	 * where K is an n byte key
61	 * ipad is the byte 0x36 repeated 64 times
62	 * opad is the byte 0x5c repeated 64 times
63	 * and text is the data being protected */
64
65	/* start out by storing key in ipad */
66	os_memset(k_pad, 0, sizeof(k_pad));
67	os_memcpy(k_pad, key, key_len);
68
69	/* XOR key with ipad values */
70	for (i = 0; i < 64; i++)
71		k_pad[i] ^= 0x36;
72
73	/* perform inner MD5 */
74	_addr[0] = k_pad;
75	_len[0] = 64;
76	for (i = 0; i < num_elem; i++) {
77		_addr[i + 1] = addr[i];
78		_len[i + 1] = len[i];
79	}
80	if (md5_vector(1 + num_elem, _addr, _len, mac))
81		return -1;
82
83	os_memset(k_pad, 0, sizeof(k_pad));
84	os_memcpy(k_pad, key, key_len);
85	/* XOR key with opad values */
86	for (i = 0; i < 64; i++)
87		k_pad[i] ^= 0x5c;
88
89	/* perform outer MD5 */
90	_addr[0] = k_pad;
91	_len[0] = 64;
92	_addr[1] = mac;
93	_len[1] = MD5_MAC_LEN;
94	return md5_vector(2, _addr, _len, mac);
95}
96
97
98/**
99 * hmac_md5 - HMAC-MD5 over data buffer (RFC 2104)
100 * @key: Key for HMAC operations
101 * @key_len: Length of the key in bytes
102 * @data: Pointers to the data area
103 * @data_len: Length of the data area
104 * @mac: Buffer for the hash (16 bytes)
105 * Returns: 0 on success, -1 on failure
106 */
107int hmac_md5(const u8 *key, size_t key_len, const u8 *data, size_t data_len,
108	      u8 *mac)
109{
110	return hmac_md5_vector(key, key_len, 1, &data, &data_len, mac);
111}
112