1/*
2 * EAP server/peer: EAP-PAX shared routines
3 * Copyright (c) 2005, 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_pax_common.h"
14
15
16/**
17 * eap_pax_kdf - PAX Key Derivation Function
18 * @mac_id: MAC ID (EAP_PAX_MAC_*) / currently, only HMAC_SHA1_128 is supported
19 * @key: Secret key (X)
20 * @key_len: Length of the secret key in bytes
21 * @identifier: Public identifier for the key (Y)
22 * @entropy: Exchanged entropy to seed the KDF (Z)
23 * @entropy_len: Length of the entropy in bytes
24 * @output_len: Output len in bytes (W)
25 * @output: Buffer for the derived key
26 * Returns: 0 on success, -1 failed
27 *
28 * RFC 4746, Section 2.6: PAX-KDF-W(X, Y, Z)
29 */
30int eap_pax_kdf(u8 mac_id, const u8 *key, size_t key_len,
31		const char *identifier,
32		const u8 *entropy, size_t entropy_len,
33		size_t output_len, u8 *output)
34{
35	u8 mac[SHA1_MAC_LEN];
36	u8 counter, *pos;
37	const u8 *addr[3];
38	size_t len[3];
39	size_t num_blocks, left;
40
41	num_blocks = (output_len + EAP_PAX_MAC_LEN - 1) / EAP_PAX_MAC_LEN;
42	if (identifier == NULL || num_blocks >= 255)
43		return -1;
44
45	/* TODO: add support for EAP_PAX_HMAC_SHA256_128 */
46	if (mac_id != EAP_PAX_MAC_HMAC_SHA1_128)
47		return -1;
48
49	addr[0] = (const u8 *) identifier;
50	len[0] = os_strlen(identifier);
51	addr[1] = entropy;
52	len[1] = entropy_len;
53	addr[2] = &counter;
54	len[2] = 1;
55
56	pos = output;
57	left = output_len;
58	for (counter = 1; counter <= (u8) num_blocks; counter++) {
59		size_t clen = left > EAP_PAX_MAC_LEN ? EAP_PAX_MAC_LEN : left;
60		hmac_sha1_vector(key, key_len, 3, addr, len, mac);
61		os_memcpy(pos, mac, clen);
62		pos += clen;
63		left -= clen;
64	}
65
66	return 0;
67}
68
69
70/**
71 * eap_pax_mac - EAP-PAX MAC
72 * @mac_id: MAC ID (EAP_PAX_MAC_*) / currently, only HMAC_SHA1_128 is supported
73 * @key: Secret key
74 * @key_len: Length of the secret key in bytes
75 * @data1: Optional data, first block; %NULL if not used
76 * @data1_len: Length of data1 in bytes
77 * @data2: Optional data, second block; %NULL if not used
78 * @data2_len: Length of data2 in bytes
79 * @data3: Optional data, third block; %NULL if not used
80 * @data3_len: Length of data3 in bytes
81 * @mac: Buffer for the MAC value (EAP_PAX_MAC_LEN = 16 bytes)
82 * Returns: 0 on success, -1 on failure
83 *
84 * Wrapper function to calculate EAP-PAX MAC.
85 */
86int eap_pax_mac(u8 mac_id, const u8 *key, size_t key_len,
87		const u8 *data1, size_t data1_len,
88		const u8 *data2, size_t data2_len,
89		const u8 *data3, size_t data3_len,
90		u8 *mac)
91{
92	u8 hash[SHA1_MAC_LEN];
93	const u8 *addr[3];
94	size_t len[3];
95	size_t count;
96
97	/* TODO: add support for EAP_PAX_HMAC_SHA256_128 */
98	if (mac_id != EAP_PAX_MAC_HMAC_SHA1_128)
99		return -1;
100
101	addr[0] = data1;
102	len[0] = data1_len;
103	addr[1] = data2;
104	len[1] = data2_len;
105	addr[2] = data3;
106	len[2] = data3_len;
107
108	count = (data1 ? 1 : 0) + (data2 ? 1 : 0) + (data3 ? 1 : 0);
109	hmac_sha1_vector(key, key_len, count, addr, len, hash);
110	os_memcpy(mac, hash, EAP_PAX_MAC_LEN);
111
112	return 0;
113}
114
115
116/**
117 * eap_pax_initial_key_derivation - EAP-PAX initial key derivation
118 * @mac_id: MAC ID (EAP_PAX_MAC_*) / currently, only HMAC_SHA1_128 is supported
119 * @ak: Authentication Key
120 * @e: Entropy
121 * @mk: Buffer for the derived Master Key
122 * @ck: Buffer for the derived Confirmation Key
123 * @ick: Buffer for the derived Integrity Check Key
124 * Returns: 0 on success, -1 on failure
125 */
126int eap_pax_initial_key_derivation(u8 mac_id, const u8 *ak, const u8 *e,
127				   u8 *mk, u8 *ck, u8 *ick)
128{
129	wpa_printf(MSG_DEBUG, "EAP-PAX: initial key derivation");
130	if (eap_pax_kdf(mac_id, ak, EAP_PAX_AK_LEN, "Master Key",
131			e, 2 * EAP_PAX_RAND_LEN, EAP_PAX_MK_LEN, mk) ||
132	    eap_pax_kdf(mac_id, mk, EAP_PAX_MK_LEN, "Confirmation Key",
133			e, 2 * EAP_PAX_RAND_LEN, EAP_PAX_CK_LEN, ck) ||
134	    eap_pax_kdf(mac_id, mk, EAP_PAX_MK_LEN, "Integrity Check Key",
135			e, 2 * EAP_PAX_RAND_LEN, EAP_PAX_ICK_LEN, ick))
136		return -1;
137
138	wpa_hexdump_key(MSG_MSGDUMP, "EAP-PAX: AK", ak, EAP_PAX_AK_LEN);
139	wpa_hexdump_key(MSG_MSGDUMP, "EAP-PAX: MK", mk, EAP_PAX_MK_LEN);
140	wpa_hexdump_key(MSG_MSGDUMP, "EAP-PAX: CK", ck, EAP_PAX_CK_LEN);
141	wpa_hexdump_key(MSG_MSGDUMP, "EAP-PAX: ICK", ick, EAP_PAX_ICK_LEN);
142
143	return 0;
144}
145