contrib/hostapd-0.5.8/eap_pax_common.c

   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 }