1/*
2 * EAP-PEAP common routines
3 * Copyright (c) 2008-2011, 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/sha1.h"
13#include "eap_peap_common.h"
14
15int peap_prfplus(int version, const u8 *key, size_t key_len,
16		 const char *label, const u8 *seed, size_t seed_len,
17		 u8 *buf, size_t buf_len)
18{
19	unsigned char counter = 0;
20	size_t pos, plen;
21	u8 hash[SHA1_MAC_LEN];
22	size_t label_len = os_strlen(label);
23	u8 extra[2];
24	const unsigned char *addr[5];
25	size_t len[5];
26
27	addr[0] = hash;
28	len[0] = 0;
29	addr[1] = (unsigned char *) label;
30	len[1] = label_len;
31	addr[2] = seed;
32	len[2] = seed_len;
33
34	if (version == 0) {
35		/*
36		 * PRF+(K, S, LEN) = T1 | T2 | ... | Tn
37		 * T1 = HMAC-SHA1(K, S | 0x01 | 0x00 | 0x00)
38		 * T2 = HMAC-SHA1(K, T1 | S | 0x02 | 0x00 | 0x00)
39		 * ...
40		 * Tn = HMAC-SHA1(K, Tn-1 | S | n | 0x00 | 0x00)
41		 */
42
43		extra[0] = 0;
44		extra[1] = 0;
45
46		addr[3] = &counter;
47		len[3] = 1;
48		addr[4] = extra;
49		len[4] = 2;
50	} else {
51		/*
52		 * PRF (K,S,LEN) = T1 | T2 | T3 | T4 | ... where:
53		 * T1 = HMAC-SHA1(K, S | LEN | 0x01)
54		 * T2 = HMAC-SHA1 (K, T1 | S | LEN | 0x02)
55		 * T3 = HMAC-SHA1 (K, T2 | S | LEN | 0x03)
56		 * T4 = HMAC-SHA1 (K, T3 | S | LEN | 0x04)
57		 *   ...
58		 */
59
60		extra[0] = buf_len & 0xff;
61
62		addr[3] = extra;
63		len[3] = 1;
64		addr[4] = &counter;
65		len[4] = 1;
66	}
67
68	pos = 0;
69	while (pos < buf_len) {
70		counter++;
71		plen = buf_len - pos;
72		if (hmac_sha1_vector(key, key_len, 5, addr, len, hash) < 0)
73			return -1;
74		if (plen >= SHA1_MAC_LEN) {
75			os_memcpy(&buf[pos], hash, SHA1_MAC_LEN);
76			pos += SHA1_MAC_LEN;
77		} else {
78			os_memcpy(&buf[pos], hash, plen);
79			break;
80		}
81		len[0] = SHA1_MAC_LEN;
82	}
83
84	return 0;
85}
86