xref: /freebsd/contrib/wpa/src/crypto/md5.c (revision 730cecb05aaf016ac52ef7cfc691ccec3a0408cd)
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  */
32 int 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  */
107 int 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