eap_pax_common.c revision 8d520ff1dc2da35cdca849e982051b86468016d8 
1/*
2 * EAP server/peer: EAP-PAX shared routines
3 * Copyright (c) 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 "crypto/sha1.h"
19#include "eap_pax_common.h"
20
21
22/**
23 * eap_pax_kdf - PAX Key Derivation Function
24 * @mac_id: MAC ID (EAP_PAX_MAC_*) / currently, only HMAC_SHA1_128 is supported
25 * @key: Secret key (X)
26 * @key_len: Length of the secret key in bytes
27 * @identifier: Public identifier for the key (Y)
28 * @entropy: Exchanged entropy to seed the KDF (Z)
29 * @entropy_len: Length of the entropy in bytes
30 * @output_len: Output len in bytes (W)
31 * @output: Buffer for the derived key
32 * Returns: 0 on success, -1 failed
33 *
34 * RFC 4746, Section 2.6: PAX-KDF-W(X, Y, Z)
35 */
36int eap_pax_kdf(u8 mac_id, const u8 *key, size_t key_len,
37		const char *identifier,
38		const u8 *entropy, size_t entropy_len,
39		size_t output_len, u8 *output)
40{
41	u8 mac[SHA1_MAC_LEN];
42	u8 counter, *pos;
43	const u8 *addr[3];
44	size_t len[3];
45	size_t num_blocks, left;
46
47	num_blocks = (output_len + EAP_PAX_MAC_LEN - 1) / EAP_PAX_MAC_LEN;
48	if (identifier == NULL || num_blocks >= 255)
49		return -1;
50
51	/* TODO: add support for EAP_PAX_HMAC_SHA256_128 */
52	if (mac_id != EAP_PAX_MAC_HMAC_SHA1_128)
53		return -1;
54
55	addr[0] = (const u8 *) identifier;
56	len[0] = os_strlen(identifier);
57	addr[1] = entropy;
58	len[1] = entropy_len;
59	addr[2] = &counter;
60	len[2] = 1;
61
62	pos = output;
63	left = output_len;
64	for (counter = 1; counter <= (u8) num_blocks; counter++) {
65		size_t clen = left > EAP_PAX_MAC_LEN ? EAP_PAX_MAC_LEN : left;
66		hmac_sha1_vector(key, key_len, 3, addr, len, mac);
67		os_memcpy(pos, mac, clen);
68		pos += clen;
69		left -= clen;
70	}
71
72	return 0;
73}
74
75
76/**
77 * eap_pax_mac - EAP-PAX MAC
78 * @mac_id: MAC ID (EAP_PAX_MAC_*) / currently, only HMAC_SHA1_128 is supported
79 * @key: Secret key
80 * @key_len: Length of the secret key in bytes
81 * @data1: Optional data, first block; %NULL if not used
82 * @data1_len: Length of data1 in bytes
83 * @data2: Optional data, second block; %NULL if not used
84 * @data2_len: Length of data2 in bytes
85 * @data3: Optional data, third block; %NULL if not used
86 * @data3_len: Length of data3 in bytes
87 * @mac: Buffer for the MAC value (EAP_PAX_MAC_LEN = 16 bytes)
88 * Returns: 0 on success, -1 on failure
89 *
90 * Wrapper function to calculate EAP-PAX MAC.
91 */
92int eap_pax_mac(u8 mac_id, const u8 *key, size_t key_len,
93		const u8 *data1, size_t data1_len,
94		const u8 *data2, size_t data2_len,
95		const u8 *data3, size_t data3_len,
96		u8 *mac)
97{
98	u8 hash[SHA1_MAC_LEN];
99	const u8 *addr[3];
100	size_t len[3];
101	size_t count;
102
103	/* TODO: add support for EAP_PAX_HMAC_SHA256_128 */
104	if (mac_id != EAP_PAX_MAC_HMAC_SHA1_128)
105		return -1;
106
107	addr[0] = data1;
108	len[0] = data1_len;
109	addr[1] = data2;
110	len[1] = data2_len;
111	addr[2] = data3;
112	len[2] = data3_len;
113
114	count = (data1 ? 1 : 0) + (data2 ? 1 : 0) + (data3 ? 1 : 0);
115	hmac_sha1_vector(key, key_len, count, addr, len, hash);
116	os_memcpy(mac, hash, EAP_PAX_MAC_LEN);
117
118	return 0;
119}
120
121
122/**
123 * eap_pax_initial_key_derivation - EAP-PAX initial key derivation
124 * @mac_id: MAC ID (EAP_PAX_MAC_*) / currently, only HMAC_SHA1_128 is supported
125 * @ak: Authentication Key
126 * @e: Entropy
127 * @mk: Buffer for the derived Master Key
128 * @ck: Buffer for the derived Confirmation Key
129 * @ick: Buffer for the derived Integrity Check Key
130 * Returns: 0 on success, -1 on failure
131 */
132int eap_pax_initial_key_derivation(u8 mac_id, const u8 *ak, const u8 *e,
133				   u8 *mk, u8 *ck, u8 *ick)
134{
135	wpa_printf(MSG_DEBUG, "EAP-PAX: initial key derivation");
136	if (eap_pax_kdf(mac_id, ak, EAP_PAX_AK_LEN, "Master Key",
137			e, 2 * EAP_PAX_RAND_LEN, EAP_PAX_MK_LEN, mk) ||
138	    eap_pax_kdf(mac_id, mk, EAP_PAX_MK_LEN, "Confirmation Key",
139			e, 2 * EAP_PAX_RAND_LEN, EAP_PAX_CK_LEN, ck) ||
140	    eap_pax_kdf(mac_id, mk, EAP_PAX_MK_LEN, "Integrity Check Key",
141			e, 2 * EAP_PAX_RAND_LEN, EAP_PAX_ICK_LEN, ick))
142		return -1;
143
144	wpa_hexdump_key(MSG_MSGDUMP, "EAP-PAX: AK", ak, EAP_PAX_AK_LEN);
145	wpa_hexdump_key(MSG_MSGDUMP, "EAP-PAX: MK", mk, EAP_PAX_MK_LEN);
146	wpa_hexdump_key(MSG_MSGDUMP, "EAP-PAX: CK", ck, EAP_PAX_CK_LEN);
147	wpa_hexdump_key(MSG_MSGDUMP, "EAP-PAX: ICK", ick, EAP_PAX_ICK_LEN);
148
149	return 0;
150}
151