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 */
eap_pax_kdf(u8 mac_id,const u8 * key,size_t key_len,const char * identifier,const u8 * entropy,size_t entropy_len,size_t output_len,u8 * output)30 int 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 if (hmac_sha1_vector(key, key_len, 3, addr, len, mac) < 0)
61 return -1;
62 os_memcpy(pos, mac, clen);
63 pos += clen;
64 left -= clen;
65 }
66
67 return 0;
68 }
69
70
71 /**
72 * eap_pax_mac - EAP-PAX MAC
73 * @mac_id: MAC ID (EAP_PAX_MAC_*) / currently, only HMAC_SHA1_128 is supported
74 * @key: Secret key
75 * @key_len: Length of the secret key in bytes
76 * @data1: Optional data, first block; %NULL if not used
77 * @data1_len: Length of data1 in bytes
78 * @data2: Optional data, second block; %NULL if not used
79 * @data2_len: Length of data2 in bytes
80 * @data3: Optional data, third block; %NULL if not used
81 * @data3_len: Length of data3 in bytes
82 * @mac: Buffer for the MAC value (EAP_PAX_MAC_LEN = 16 bytes)
83 * Returns: 0 on success, -1 on failure
84 *
85 * Wrapper function to calculate EAP-PAX MAC.
86 */
eap_pax_mac(u8 mac_id,const u8 * key,size_t key_len,const u8 * data1,size_t data1_len,const u8 * data2,size_t data2_len,const u8 * data3,size_t data3_len,u8 * mac)87 int eap_pax_mac(u8 mac_id, const u8 *key, size_t key_len,
88 const u8 *data1, size_t data1_len,
89 const u8 *data2, size_t data2_len,
90 const u8 *data3, size_t data3_len,
91 u8 *mac)
92 {
93 u8 hash[SHA1_MAC_LEN];
94 const u8 *addr[3];
95 size_t len[3];
96 size_t count;
97
98 /* TODO: add support for EAP_PAX_HMAC_SHA256_128 */
99 if (mac_id != EAP_PAX_MAC_HMAC_SHA1_128)
100 return -1;
101
102 addr[0] = data1;
103 len[0] = data1_len;
104 addr[1] = data2;
105 len[1] = data2_len;
106 addr[2] = data3;
107 len[2] = data3_len;
108
109 count = (data1 ? 1 : 0) + (data2 ? 1 : 0) + (data3 ? 1 : 0);
110 if (hmac_sha1_vector(key, key_len, count, addr, len, hash) < 0)
111 return -1;
112 os_memcpy(mac, hash, EAP_PAX_MAC_LEN);
113
114 return 0;
115 }
116
117
118 /**
119 * eap_pax_initial_key_derivation - EAP-PAX initial key derivation
120 * @mac_id: MAC ID (EAP_PAX_MAC_*) / currently, only HMAC_SHA1_128 is supported
121 * @ak: Authentication Key
122 * @e: Entropy
123 * @mk: Buffer for the derived Master Key
124 * @ck: Buffer for the derived Confirmation Key
125 * @ick: Buffer for the derived Integrity Check Key
126 * @mid: Buffer for the derived Method ID
127 * Returns: 0 on success, -1 on failure
128 */
eap_pax_initial_key_derivation(u8 mac_id,const u8 * ak,const u8 * e,u8 * mk,u8 * ck,u8 * ick,u8 * mid)129 int eap_pax_initial_key_derivation(u8 mac_id, const u8 *ak, const u8 *e,
130 u8 *mk, u8 *ck, u8 *ick, u8 *mid)
131 {
132 wpa_printf(MSG_DEBUG, "EAP-PAX: initial key derivation");
133 if (eap_pax_kdf(mac_id, ak, EAP_PAX_AK_LEN, "Master Key",
134 e, 2 * EAP_PAX_RAND_LEN, EAP_PAX_MK_LEN, mk) ||
135 eap_pax_kdf(mac_id, mk, EAP_PAX_MK_LEN, "Confirmation Key",
136 e, 2 * EAP_PAX_RAND_LEN, EAP_PAX_CK_LEN, ck) ||
137 eap_pax_kdf(mac_id, mk, EAP_PAX_MK_LEN, "Integrity Check Key",
138 e, 2 * EAP_PAX_RAND_LEN, EAP_PAX_ICK_LEN, ick) ||
139 eap_pax_kdf(mac_id, mk, EAP_PAX_MK_LEN, "Method ID",
140 e, 2 * EAP_PAX_RAND_LEN, EAP_PAX_MID_LEN, mid))
141 return -1;
142
143 wpa_hexdump_key(MSG_MSGDUMP, "EAP-PAX: AK", ak, EAP_PAX_AK_LEN);
144 wpa_hexdump_key(MSG_MSGDUMP, "EAP-PAX: MK", mk, EAP_PAX_MK_LEN);
145 wpa_hexdump_key(MSG_MSGDUMP, "EAP-PAX: CK", ck, EAP_PAX_CK_LEN);
146 wpa_hexdump_key(MSG_MSGDUMP, "EAP-PAX: ICK", ick, EAP_PAX_ICK_LEN);
147 wpa_hexdump_key(MSG_MSGDUMP, "EAP-PAX: MID", mid, EAP_PAX_MID_LEN);
148
149 return 0;
150 }
151