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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 | */ | |
31 | void hmac_md5_vector(const u8 *key, size_t key_len, size_t num_elem, | |
32 | const u8 *addr[], const size_t *len, u8 *mac) | |
33 | { | |
34 | u8 k_pad[64]; /* padding - key XORd with ipad/opad */ | |
35 | u8 tk[16]; | |
36 | const u8 *_addr[6]; | |
37 | size_t i, _len[6]; | |
38 | ||
39 | if (num_elem > 5) { | |
40 | /* | |
41 | * Fixed limit on the number of fragments to avoid having to | |
42 | * allocate memory (which could fail). | |
43 | */ | |
44 | return; | |
45 | } | |
46 | ||
47 | /* if key is longer than 64 bytes reset it to key = MD5(key) */ | |
48 | if (key_len > 64) { | |
49 | md5_vector(1, &key, &key_len, tk); | |
50 | key = tk; | |
51 | key_len = 16; | |
52 | } | |
53 | ||
54 | /* the HMAC_MD5 transform looks like: | |
55 | * | |
56 | * MD5(K XOR opad, MD5(K XOR ipad, text)) | |
57 | * | |
58 | * where K is an n byte key | |
59 | * ipad is the byte 0x36 repeated 64 times | |
60 | * opad is the byte 0x5c repeated 64 times | |
61 | * and text is the data being protected */ | |
62 | ||
63 | /* start out by storing key in ipad */ | |
64 | os_memset(k_pad, 0, sizeof(k_pad)); | |
65 | os_memcpy(k_pad, key, key_len); | |
66 | ||
67 | /* XOR key with ipad values */ | |
68 | for (i = 0; i < 64; i++) | |
69 | k_pad[i] ^= 0x36; | |
70 | ||
71 | /* perform inner MD5 */ | |
72 | _addr[0] = k_pad; | |
73 | _len[0] = 64; | |
74 | for (i = 0; i < num_elem; i++) { | |
75 | _addr[i + 1] = addr[i]; | |
76 | _len[i + 1] = len[i]; | |
77 | } | |
78 | md5_vector(1 + num_elem, _addr, _len, mac); | |
79 | ||
80 | os_memset(k_pad, 0, sizeof(k_pad)); | |
81 | os_memcpy(k_pad, key, key_len); | |
82 | /* XOR key with opad values */ | |
83 | for (i = 0; i < 64; i++) | |
84 | k_pad[i] ^= 0x5c; | |
85 | ||
86 | /* perform outer MD5 */ | |
87 | _addr[0] = k_pad; | |
88 | _len[0] = 64; | |
89 | _addr[1] = mac; | |
90 | _len[1] = MD5_MAC_LEN; | |
91 | md5_vector(2, _addr, _len, mac); | |
92 | } | |
93 | ||
94 | ||
95 | /** | |
96 | * hmac_md5 - HMAC-MD5 over data buffer (RFC 2104) | |
97 | * @key: Key for HMAC operations | |
98 | * @key_len: Length of the key in bytes | |
99 | * @data: Pointers to the data area | |
100 | * @data_len: Length of the data area | |
101 | * @mac: Buffer for the hash (16 bytes) | |
102 | */ | |
103 | void hmac_md5(const u8 *key, size_t key_len, const u8 *data, size_t data_len, | |
104 | u8 *mac) | |
105 | { | |
106 | hmac_md5_vector(key, key_len, 1, &data, &data_len, mac); | |
107 | } |