1 /*
2 * EAP server/peer: EAP-PSK shared routines
3 * Copyright (c) 2004-2006, 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 "aes_wrap.h"
19 #include "eap_defs.h"
20 #include "eap_psk_common.h"
21
22 #define aes_block_size 16
23
24
eap_psk_key_setup(const u8 * psk,u8 * ak,u8 * kdk)25 void eap_psk_key_setup(const u8 *psk, u8 *ak, u8 *kdk)
26 {
27 os_memset(ak, 0, aes_block_size);
28 aes_128_encrypt_block(psk, ak, ak);
29 os_memcpy(kdk, ak, aes_block_size);
30 ak[aes_block_size - 1] ^= 0x01;
31 kdk[aes_block_size - 1] ^= 0x02;
32 aes_128_encrypt_block(psk, ak, ak);
33 aes_128_encrypt_block(psk, kdk, kdk);
34 }
35
36
eap_psk_derive_keys(const u8 * kdk,const u8 * rand_p,u8 * tek,u8 * msk,u8 * emsk)37 void eap_psk_derive_keys(const u8 *kdk, const u8 *rand_p, u8 *tek, u8 *msk,
38 u8 *emsk)
39 {
40 u8 hash[aes_block_size];
41 u8 counter = 1;
42 int i;
43
44 aes_128_encrypt_block(kdk, rand_p, hash);
45
46 hash[aes_block_size - 1] ^= counter;
47 aes_128_encrypt_block(kdk, hash, tek);
48 hash[aes_block_size - 1] ^= counter;
49 counter++;
50
51 for (i = 0; i < EAP_MSK_LEN / aes_block_size; i++) {
52 hash[aes_block_size - 1] ^= counter;
53 aes_128_encrypt_block(kdk, hash, &msk[i * aes_block_size]);
54 hash[aes_block_size - 1] ^= counter;
55 counter++;
56 }
57
58 for (i = 0; i < EAP_EMSK_LEN / aes_block_size; i++) {
59 hash[aes_block_size - 1] ^= counter;
60 aes_128_encrypt_block(kdk, hash, &emsk[i * aes_block_size]);
61 hash[aes_block_size - 1] ^= counter;
62 counter++;
63 }
64 }
65