Line data Source code
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 : */
30 110 : 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 :
41 110 : num_blocks = (output_len + EAP_PAX_MAC_LEN - 1) / EAP_PAX_MAC_LEN;
42 110 : if (identifier == NULL || num_blocks >= 255)
43 0 : return -1;
44 :
45 : /* TODO: add support for EAP_PAX_HMAC_SHA256_128 */
46 110 : if (mac_id != EAP_PAX_MAC_HMAC_SHA1_128)
47 0 : return -1;
48 :
49 110 : addr[0] = (const u8 *) identifier;
50 110 : len[0] = os_strlen(identifier);
51 110 : addr[1] = entropy;
52 110 : len[1] = entropy_len;
53 110 : addr[2] = &counter;
54 110 : len[2] = 1;
55 :
56 110 : pos = output;
57 110 : left = output_len;
58 298 : for (counter = 1; counter <= (u8) num_blocks; counter++) {
59 188 : size_t clen = left > EAP_PAX_MAC_LEN ? EAP_PAX_MAC_LEN : left;
60 188 : hmac_sha1_vector(key, key_len, 3, addr, len, mac);
61 188 : os_memcpy(pos, mac, clen);
62 188 : pos += clen;
63 188 : left -= clen;
64 : }
65 :
66 110 : 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 : */
86 161 : int 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 */
98 161 : if (mac_id != EAP_PAX_MAC_HMAC_SHA1_128)
99 0 : return -1;
100 :
101 161 : addr[0] = data1;
102 161 : len[0] = data1_len;
103 161 : addr[1] = data2;
104 161 : len[1] = data2_len;
105 161 : addr[2] = data3;
106 161 : len[2] = data3_len;
107 :
108 161 : count = (data1 ? 1 : 0) + (data2 ? 1 : 0) + (data3 ? 1 : 0);
109 161 : hmac_sha1_vector(key, key_len, count, addr, len, hash);
110 161 : os_memcpy(mac, hash, EAP_PAX_MAC_LEN);
111 :
112 161 : 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 : */
126 28 : int eap_pax_initial_key_derivation(u8 mac_id, const u8 *ak, const u8 *e,
127 : u8 *mk, u8 *ck, u8 *ick)
128 : {
129 28 : wpa_printf(MSG_DEBUG, "EAP-PAX: initial key derivation");
130 28 : if (eap_pax_kdf(mac_id, ak, EAP_PAX_AK_LEN, "Master Key",
131 28 : e, 2 * EAP_PAX_RAND_LEN, EAP_PAX_MK_LEN, mk) ||
132 28 : eap_pax_kdf(mac_id, mk, EAP_PAX_MK_LEN, "Confirmation Key",
133 28 : e, 2 * EAP_PAX_RAND_LEN, EAP_PAX_CK_LEN, ck) ||
134 28 : 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 0 : return -1;
137 :
138 28 : wpa_hexdump_key(MSG_MSGDUMP, "EAP-PAX: AK", ak, EAP_PAX_AK_LEN);
139 28 : wpa_hexdump_key(MSG_MSGDUMP, "EAP-PAX: MK", mk, EAP_PAX_MK_LEN);
140 28 : wpa_hexdump_key(MSG_MSGDUMP, "EAP-PAX: CK", ck, EAP_PAX_CK_LEN);
141 28 : wpa_hexdump_key(MSG_MSGDUMP, "EAP-PAX: ICK", ick, EAP_PAX_ICK_LEN);
142 :
143 28 : return 0;
144 : }
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