src/eap_common/eap_peap_common.c

   1 /*
   2  * EAP-PEAP common routines
   3  * Copyright (c) 2008-2011, Jouni Malinen <j@w1.fi>
   4  *
   5  * This software may be distributed under the terms of the BSD license.
   6  * See README for more details.
   7  */
   8
   9 #include "includes.h"
  10
  11 #include "common.h"
  12 #include "crypto/sha1.h"
  13 #include "eap_peap_common.h"
  14
  15 int peap_prfplus(int version, const u8 *key, size_t key_len,
  16                  const char *label, const u8 *seed, size_t seed_len,
  17                  u8 *buf, size_t buf_len)
  18 {
  19         unsigned char counter = 0;
  20         size_t pos, plen;
  21         u8 hash[SHA1_MAC_LEN];
  22         size_t label_len = os_strlen(label);
  23         u8 extra[2];
  24         const unsigned char *addr[5];
  25         size_t len[5];
  26
  27         addr[0] = hash;
  28         len[0] = 0;
  29         addr[1] = (unsigned char *) label;
  30         len[1] = label_len;
  31         addr[2] = seed;
  32         len[2] = seed_len;
  33
  34         if (version == 0) {
  35                 /*
  36                  * PRF+(K, S, LEN) = T1 | T2 | ... | Tn
  37                  * T1 = HMAC-SHA1(K, S | 0x01 | 0x00 | 0x00)
  38                  * T2 = HMAC-SHA1(K, T1 | S | 0x02 | 0x00 | 0x00)
  39                  * ...
  40                  * Tn = HMAC-SHA1(K, Tn-1 | S | n | 0x00 | 0x00)
  41                  */
  42
  43                 extra[0] = 0;
  44                 extra[1] = 0;
  45
  46                 addr[3] = &counter;
  47                 len[3] = 1;
  48                 addr[4] = extra;
  49                 len[4] = 2;
  50         } else {
  51                 /*
  52                  * PRF (K,S,LEN) = T1 | T2 | T3 | T4 | ... where:
  53                  * T1 = HMAC-SHA1(K, S | LEN | 0x01)
  54                  * T2 = HMAC-SHA1 (K, T1 | S | LEN | 0x02)
  55                  * T3 = HMAC-SHA1 (K, T2 | S | LEN | 0x03)
  56                  * T4 = HMAC-SHA1 (K, T3 | S | LEN | 0x04)
  57                  *   ...
  58                  */
  59
  60                 extra[0] = buf_len & 0xff;
  61
  62                 addr[3] = extra;
  63                 len[3] = 1;
  64                 addr[4] = &counter;
  65                 len[4] = 1;
  66         }
  67
  68         pos = 0;
  69         while (pos < buf_len) {
  70                 counter++;
  71                 plen = buf_len - pos;
  72                 if (hmac_sha1_vector(key, key_len, 5, addr, len, hash) < 0)
  73                         return -1;
  74                 if (plen >= SHA1_MAC_LEN) {
  75                         os_memcpy(&buf[pos], hash, SHA1_MAC_LEN);
  76                         pos += SHA1_MAC_LEN;
  77                 } else {
  78                         os_memcpy(&buf[pos], hash, plen);
  79                         break;
  80                 }
  81                 len[0] = SHA1_MAC_LEN;
  82         }
  83
  84         return 0;
  85 }