src/eap_common/eap_peap_common.c

   1 /*
   2  * EAP-PEAP common routines
   3  * Copyright (c) 2008, 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 "crypto/sha1.h"
  19 #include "eap_peap_common.h"
  20
  21 void peap_prfplus(int version, const u8 *key, size_t key_len,
  22                   const char *label, const u8 *seed, size_t seed_len,
  23                   u8 *buf, size_t buf_len)
  24 {
  25         unsigned char counter = 0;
  26         size_t pos, plen;
  27         u8 hash[SHA1_MAC_LEN];
  28         size_t label_len = os_strlen(label);
  29         u8 extra[2];
  30         const unsigned char *addr[5];
  31         size_t len[5];
  32
  33         addr[0] = hash;
  34         len[0] = 0;
  35         addr[1] = (unsigned char *) label;
  36         len[1] = label_len;
  37         addr[2] = seed;
  38         len[2] = seed_len;
  39
  40         if (version == 0) {
  41                 /*
  42                  * PRF+(K, S, LEN) = T1 | T2 | ... | Tn
  43                  * T1 = HMAC-SHA1(K, S | 0x01 | 0x00 | 0x00)
  44                  * T2 = HMAC-SHA1(K, T1 | S | 0x02 | 0x00 | 0x00)
  45                  * ...
  46                  * Tn = HMAC-SHA1(K, Tn-1 | S | n | 0x00 | 0x00)
  47                  */
  48
  49                 extra[0] = 0;
  50                 extra[1] = 0;
  51
  52                 addr[3] = &counter;
  53                 len[3] = 1;
  54                 addr[4] = extra;
  55                 len[4] = 2;
  56         } else {
  57                 /*
  58                  * PRF (K,S,LEN) = T1 | T2 | T3 | T4 | ... where:
  59                  * T1 = HMAC-SHA1(K, S | LEN | 0x01)
  60                  * T2 = HMAC-SHA1 (K, T1 | S | LEN | 0x02)
  61                  * T3 = HMAC-SHA1 (K, T2 | S | LEN | 0x03)
  62                  * T4 = HMAC-SHA1 (K, T3 | S | LEN | 0x04)
  63                  *   ...
  64                  */
  65
  66                 extra[0] = buf_len & 0xff;
  67
  68                 addr[3] = extra;
  69                 len[3] = 1;
  70                 addr[4] = &counter;
  71                 len[4] = 1;
  72         }
  73
  74         pos = 0;
  75         while (pos < buf_len) {
  76                 counter++;
  77                 plen = buf_len - pos;
  78                 hmac_sha1_vector(key, key_len, 5, addr, len, hash);
  79                 if (plen >= SHA1_MAC_LEN) {
  80                         os_memcpy(&buf[pos], hash, SHA1_MAC_LEN);
  81                         pos += SHA1_MAC_LEN;
  82                 } else {
  83                         os_memcpy(&buf[pos], hash, plen);
  84                         break;
  85                 }
  86                 len[0] = SHA1_MAC_LEN;
  87         }
  88 }