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  */
hmac_md5_vector(const u8 * key,size_t key_len,size_t num_elem,const u8 * addr[],const size_t * len,u8 * mac)26 int 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  */
hmac_md5(const u8 * key,size_t key_len,const u8 * data,size_t data_len,u8 * mac)105 int 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