contrib/hostapd-0.5.8/eap_psk_common.c

   1 /*
   2  * EAP server/peer: EAP-PSK shared routines
   3  * Copyright (c) 2004-2006, 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 "aes_wrap.h"
  19 #include "eap_defs.h"
  20 #include "eap_psk_common.h"
  21
  22 #define aes_block_size 16
  23
  24
  25 void eap_psk_key_setup(const u8 *psk, u8 *ak, u8 *kdk)
  26 {
  27         os_memset(ak, 0, aes_block_size);
  28         aes_128_encrypt_block(psk, ak, ak);
  29         os_memcpy(kdk, ak, aes_block_size);
  30         ak[aes_block_size - 1] ^= 0x01;
  31         kdk[aes_block_size - 1] ^= 0x02;
  32         aes_128_encrypt_block(psk, ak, ak);
  33         aes_128_encrypt_block(psk, kdk, kdk);
  34 }
  35
  36
  37 void eap_psk_derive_keys(const u8 *kdk, const u8 *rand_p, u8 *tek, u8 *msk,
  38                          u8 *emsk)
  39 {
  40         u8 hash[aes_block_size];
  41         u8 counter = 1;
  42         int i;
  43
  44         aes_128_encrypt_block(kdk, rand_p, hash);
  45
  46         hash[aes_block_size - 1] ^= counter;
  47         aes_128_encrypt_block(kdk, hash, tek);
  48         hash[aes_block_size - 1] ^= counter;
  49         counter++;
  50
  51         for (i = 0; i < EAP_MSK_LEN / aes_block_size; i++) {
  52                 hash[aes_block_size - 1] ^= counter;
  53                 aes_128_encrypt_block(kdk, hash, &msk[i * aes_block_size]);
  54                 hash[aes_block_size - 1] ^= counter;
  55                 counter++;
  56         }
  57
  58         for (i = 0; i < EAP_EMSK_LEN / aes_block_size; i++) {
  59                 hash[aes_block_size - 1] ^= counter;
  60                 aes_128_encrypt_block(kdk, hash, &emsk[i * aes_block_size]);
  61                 hash[aes_block_size - 1] ^= counter;
  62                 counter++;
  63         }
  64 }