eap_psk_common.c revision 214734 
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 "crypto/aes_wrap.h"
19#include "eap_defs.h"
20#include "eap_psk_common.h"
21
22#define aes_block_size 16
23
24
25int eap_psk_key_setup(const u8 *psk, u8 *ak, u8 *kdk)
26{
27	os_memset(ak, 0, aes_block_size);
28	if (aes_128_encrypt_block(psk, ak, ak))
29		return -1;
30	os_memcpy(kdk, ak, aes_block_size);
31	ak[aes_block_size - 1] ^= 0x01;
32	kdk[aes_block_size - 1] ^= 0x02;
33	if (aes_128_encrypt_block(psk, ak, ak) ||
34	    aes_128_encrypt_block(psk, kdk, kdk))
35		return -1;
36	return 0;
37}
38
39
40int eap_psk_derive_keys(const u8 *kdk, const u8 *rand_p, u8 *tek, u8 *msk,
41			u8 *emsk)
42{
43	u8 hash[aes_block_size];
44	u8 counter = 1;
45	int i;
46
47	if (aes_128_encrypt_block(kdk, rand_p, hash))
48		return -1;
49
50	hash[aes_block_size - 1] ^= counter;
51	if (aes_128_encrypt_block(kdk, hash, tek))
52		return -1;
53	hash[aes_block_size - 1] ^= counter;
54	counter++;
55
56	for (i = 0; i < EAP_MSK_LEN / aes_block_size; i++) {
57		hash[aes_block_size - 1] ^= counter;
58		if (aes_128_encrypt_block(kdk, hash, &msk[i * aes_block_size]))
59			return -1;
60		hash[aes_block_size - 1] ^= counter;
61		counter++;
62	}
63
64	for (i = 0; i < EAP_EMSK_LEN / aes_block_size; i++) {
65		hash[aes_block_size - 1] ^= counter;
66		if (aes_128_encrypt_block(kdk, hash,
67					  &emsk[i * aes_block_size]))
68			return -1;
69		hash[aes_block_size - 1] ^= counter;
70		counter++;
71	}
72
73	return 0;
74}
75