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