1 /* 2 * EAP server/peer: EAP-PAX shared routines 3 * Copyright (c) 2005, Jouni Malinen <j@w1.fi> 4 * 5 * This program is free software; you can redistribute it and/or modify 6 * it under the terms of the GNU General Public License version 2 as 7 * published by the Free Software Foundation. 8 * 9 * Alternatively, this software may be distributed under the terms of BSD 10 * license. 11 * 12 * See README and COPYING for more details. 13 */ 14 15 #include "includes.h" 16 17 #include "common.h" 18 #include "sha1.h" 19 #include "eap_pax_common.h" 20 21 22 /** 23 * eap_pax_kdf - PAX Key Derivation Function 24 * @mac_id: MAC ID (EAP_PAX_MAC_*) / currently, only HMAC_SHA1_128 is supported 25 * @key: Secret key (X) 26 * @key_len: Length of the secret key in bytes 27 * @identifier: Public identifier for the key (Y) 28 * @entropy: Exchanged entropy to seed the KDF (Z) 29 * @entropy_len: Length of the entropy in bytes 30 * @output_len: Output len in bytes (W) 31 * @output: Buffer for the derived key 32 * Returns: 0 on success, -1 failed 33 * 34 * RFC 4746, Section 2.6: PAX-KDF-W(X, Y, Z) 35 */ 36 int eap_pax_kdf(u8 mac_id, const u8 *key, size_t key_len, 37 const char *identifier, 38 const u8 *entropy, size_t entropy_len, 39 size_t output_len, u8 *output) 40 { 41 u8 mac[SHA1_MAC_LEN]; 42 u8 counter, *pos; 43 const u8 *addr[3]; 44 size_t len[3]; 45 size_t num_blocks, left; 46 47 num_blocks = (output_len + EAP_PAX_MAC_LEN - 1) / EAP_PAX_MAC_LEN; 48 if (identifier == NULL || num_blocks >= 255) 49 return -1; 50 51 /* TODO: add support for EAP_PAX_HMAC_SHA256_128 */ 52 if (mac_id != EAP_PAX_MAC_HMAC_SHA1_128) 53 return -1; 54 55 addr[0] = (const u8 *) identifier; 56 len[0] = os_strlen(identifier); 57 addr[1] = entropy; 58 len[1] = entropy_len; 59 addr[2] = &counter; 60 len[2] = 1; 61 62 pos = output; 63 left = output_len; 64 for (counter = 1; counter <= (u8) num_blocks; counter++) { 65 size_t clen = left > EAP_PAX_MAC_LEN ? EAP_PAX_MAC_LEN : left; 66 hmac_sha1_vector(key, key_len, 3, addr, len, mac); 67 os_memcpy(pos, mac, clen); 68 pos += clen; 69 left -= clen; 70 } 71 72 return 0; 73 } 74 75 76 /** 77 * eap_pax_mac - EAP-PAX MAC 78 * @mac_id: MAC ID (EAP_PAX_MAC_*) / currently, only HMAC_SHA1_128 is supported 79 * @key: Secret key 80 * @key_len: Length of the secret key in bytes 81 * @data1: Optional data, first block; %NULL if not used 82 * @data1_len: Length of data1 in bytes 83 * @data2: Optional data, second block; %NULL if not used 84 * @data2_len: Length of data2 in bytes 85 * @data3: Optional data, third block; %NULL if not used 86 * @data3_len: Length of data3 in bytes 87 * @mac: Buffer for the MAC value (EAP_PAX_MAC_LEN = 16 bytes) 88 * Returns: 0 on success, -1 on failure 89 * 90 * Wrapper function to calculate EAP-PAX MAC. 91 */ 92 int eap_pax_mac(u8 mac_id, const u8 *key, size_t key_len, 93 const u8 *data1, size_t data1_len, 94 const u8 *data2, size_t data2_len, 95 const u8 *data3, size_t data3_len, 96 u8 *mac) 97 { 98 u8 hash[SHA1_MAC_LEN]; 99 const u8 *addr[3]; 100 size_t len[3]; 101 size_t count; 102 103 /* TODO: add support for EAP_PAX_HMAC_SHA256_128 */ 104 if (mac_id != EAP_PAX_MAC_HMAC_SHA1_128) 105 return -1; 106 107 addr[0] = data1; 108 len[0] = data1_len; 109 addr[1] = data2; 110 len[1] = data2_len; 111 addr[2] = data3; 112 len[2] = data3_len; 113 114 count = (data1 ? 1 : 0) + (data2 ? 1 : 0) + (data3 ? 1 : 0); 115 hmac_sha1_vector(key, key_len, count, addr, len, hash); 116 os_memcpy(mac, hash, EAP_PAX_MAC_LEN); 117 118 return 0; 119 } 120 121 122 /** 123 * eap_pax_initial_key_derivation - EAP-PAX initial key derivation 124 * @mac_id: MAC ID (EAP_PAX_MAC_*) / currently, only HMAC_SHA1_128 is supported 125 * @ak: Authentication Key 126 * @e: Entropy 127 * @mk: Buffer for the derived Master Key 128 * @ck: Buffer for the derived Confirmation Key 129 * @ick: Buffer for the derived Integrity Check Key 130 * Returns: 0 on success, -1 on failure 131 */ 132 int eap_pax_initial_key_derivation(u8 mac_id, const u8 *ak, const u8 *e, 133 u8 *mk, u8 *ck, u8 *ick) 134 { 135 wpa_printf(MSG_DEBUG, "EAP-PAX: initial key derivation"); 136 if (eap_pax_kdf(mac_id, ak, EAP_PAX_AK_LEN, "Master Key", 137 e, 2 * EAP_PAX_RAND_LEN, EAP_PAX_MK_LEN, mk) || 138 eap_pax_kdf(mac_id, mk, EAP_PAX_MK_LEN, "Confirmation Key", 139 e, 2 * EAP_PAX_RAND_LEN, EAP_PAX_CK_LEN, ck) || 140 eap_pax_kdf(mac_id, mk, EAP_PAX_MK_LEN, "Integrity Check Key", 141 e, 2 * EAP_PAX_RAND_LEN, EAP_PAX_ICK_LEN, ick)) 142 return -1; 143 144 wpa_hexdump_key(MSG_MSGDUMP, "EAP-PAX: AK", ak, EAP_PAX_AK_LEN); 145 wpa_hexdump_key(MSG_MSGDUMP, "EAP-PAX: MK", mk, EAP_PAX_MK_LEN); 146 wpa_hexdump_key(MSG_MSGDUMP, "EAP-PAX: CK", ck, EAP_PAX_CK_LEN); 147 wpa_hexdump_key(MSG_MSGDUMP, "EAP-PAX: ICK", ick, EAP_PAX_ICK_LEN); 148 149 return 0; 150 } 151