1/*
2 * EAP server/peer: EAP-PSK shared routines
3 * Copyright (c) 2004-2006, 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 "crypto/aes_wrap.h"
13#include "eap_defs.h"
14#include "eap_psk_common.h"
15
16#define aes_block_size 16
17
18
19int eap_psk_key_setup(const u8 *psk, u8 *ak, u8 *kdk)
20{
21	os_memset(ak, 0, aes_block_size);
22	if (aes_128_encrypt_block(psk, ak, ak))
23		return -1;
24	os_memcpy(kdk, ak, aes_block_size);
25	ak[aes_block_size - 1] ^= 0x01;
26	kdk[aes_block_size - 1] ^= 0x02;
27	if (aes_128_encrypt_block(psk, ak, ak) ||
28	    aes_128_encrypt_block(psk, kdk, kdk))
29		return -1;
30	return 0;
31}
32
33
34int eap_psk_derive_keys(const u8 *kdk, const u8 *rand_p, u8 *tek, u8 *msk,
35			u8 *emsk)
36{
37	u8 hash[aes_block_size];
38	u8 counter = 1;
39	int i;
40
41	if (aes_128_encrypt_block(kdk, rand_p, hash))
42		return -1;
43
44	hash[aes_block_size - 1] ^= counter;
45	if (aes_128_encrypt_block(kdk, hash, tek))
46		return -1;
47	hash[aes_block_size - 1] ^= counter;
48	counter++;
49
50	for (i = 0; i < EAP_MSK_LEN / aes_block_size; i++) {
51		hash[aes_block_size - 1] ^= counter;
52		if (aes_128_encrypt_block(kdk, hash, &msk[i * aes_block_size]))
53			return -1;
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		if (aes_128_encrypt_block(kdk, hash,
61					  &emsk[i * aes_block_size]))
62			return -1;
63		hash[aes_block_size - 1] ^= counter;
64		counter++;
65	}
66
67	return 0;
68}
69