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