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