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eap_pax_common.c
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eap_pax_common.c
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/*
* WPA Supplicant / EAP-PAX shared routines
* Copyright (c) 2005, Jouni Malinen <jkmaline@cc.hut.fi>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* Alternatively, this software may be distributed under the terms of BSD
* license.
*
* See README and COPYING for more details.
*/
#include "includes.h"
#include "common.h"
#include "sha1.h"
#include "eap_pax_common.h"
/**
* eap_pax_kdf - PAX Key Derivation Function
* @mac_id: MAC ID (EAP_PAX_MAC_*) / currently, only HMAC_SHA1_128 is supported
* @key: Secret key (X)
* @key_len: Length of the secret key in bytes
* @identifier: Public identifier for the key (Y)
* @entropy: Exchanged entropy to seed the KDF (Z)
* @entropy_len: Length of the entropy in bytes
* @output_len: Output len in bytes (W)
* @output: Buffer for the derived key
* Returns: 0 on success, -1 failed
*
* draft-clancy-eap-pax-04.txt, chap. 2.5: PAX-KDF-W(X, Y, Z)
*/
int 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)
{
u8 mac[SHA1_MAC_LEN];
u8 counter, *pos;
const u8 *addr[3];
size_t len[3];
size_t num_blocks, left;
num_blocks = (output_len + EAP_PAX_MAC_LEN - 1) / EAP_PAX_MAC_LEN;
if (identifier == NULL || num_blocks >= 255)
return -1;
/* TODO: add support for EAP_PAX_MAC_AES_CBC_MAC_128 */
if (mac_id != EAP_PAX_MAC_HMAC_SHA1_128)
return -1;
addr[0] = (const u8 *) identifier;
len[0] = strlen(identifier);
addr[1] = entropy;
len[1] = entropy_len;
addr[2] = &counter;
len[2] = 1;
pos = output;
left = output_len;
for (counter = 1; counter <= (u8) num_blocks; counter++) {
size_t clen = left > EAP_PAX_MAC_LEN ? EAP_PAX_MAC_LEN : left;
hmac_sha1_vector(key, key_len, 3, addr, len, mac);
memcpy(pos, mac, clen);
pos += clen;
left -= clen;
}
return 0;
}
/**
* eap_pax_mac - EAP-PAX MAC
* @mac_id: MAC ID (EAP_PAX_MAC_*) / currently, only HMAC_SHA1_128 is supported
* @key: Secret key
* @key_len: Length of the secret key in bytes
* @data1: Optional data, first block; %NULL if not used
* @data1_len: Length of data1 in bytes
* @data2: Optional data, second block; %NULL if not used
* @data2_len: Length of data2 in bytes
* @data3: Optional data, third block; %NULL if not used
* @data3_len: Length of data3 in bytes
* @mac: Buffer for the MAC value (EAP_PAX_MAC_LEN = 16 bytes)
* Returns: 0 on success, -1 on failure
*
* Wrapper function to calculate EAP-PAX MAC.
*/
int 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)
{
u8 hash[SHA1_MAC_LEN];
const u8 *addr[3];
size_t len[3];
size_t count;
/* TODO: add support for EAP_PAX_MAC_AES_CBC_MAC_128 */
if (mac_id != EAP_PAX_MAC_HMAC_SHA1_128)
return -1;
addr[0] = data1;
len[0] = data1_len;
addr[1] = data2;
len[1] = data2_len;
addr[2] = data3;
len[2] = data3_len;
count = (data1 ? 1 : 0) + (data2 ? 1 : 0) + (data3 ? 1 : 0);
hmac_sha1_vector(key, key_len, count, addr, len, hash);
memcpy(mac, hash, EAP_PAX_MAC_LEN);
return 0;
}
/**
* eap_pax_initial_key_derivation - EAP-PAX initial key derivation
* @mac_id: MAC ID (EAP_PAX_MAC_*) / currently, only HMAC_SHA1_128 is supported
* @ak: Authentication Key
* @e: Entropy
* @mk: Buffer for the derived Master Key
* @ck: Buffer for the derived Confirmation Key
* @ick: Buffer for the derived Integrity Check Key
* Returns: 0 on success, -1 on failure
*/
int eap_pax_initial_key_derivation(u8 mac_id, const u8 *ak, const u8 *e,
u8 *mk, u8 *ck, u8 *ick)
{
wpa_printf(MSG_DEBUG, "EAP-PAX: initial key derivation");
if (eap_pax_kdf(mac_id, ak, EAP_PAX_AK_LEN, "Master Key",
e, 2 * EAP_PAX_RAND_LEN, EAP_PAX_MK_LEN, mk) ||
eap_pax_kdf(mac_id, mk, EAP_PAX_MK_LEN, "Confirmation Key",
e, 2 * EAP_PAX_RAND_LEN, EAP_PAX_CK_LEN, ck) ||
eap_pax_kdf(mac_id, mk, EAP_PAX_MK_LEN, "Integrity Check Key",
e, 2 * EAP_PAX_RAND_LEN, EAP_PAX_ICK_LEN, ick))
return -1;
wpa_hexdump_key(MSG_MSGDUMP, "EAP-PAX: AK", ak, EAP_PAX_AK_LEN);
wpa_hexdump_key(MSG_MSGDUMP, "EAP-PAX: MK", mk, EAP_PAX_MK_LEN);
wpa_hexdump_key(MSG_MSGDUMP, "EAP-PAX: CK", ck, EAP_PAX_CK_LEN);
wpa_hexdump_key(MSG_MSGDUMP, "EAP-PAX: ICK", ick, EAP_PAX_ICK_LEN);
return 0;
}