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