workbench/network/WirelessManager/src/crypto/sha1-tprf.c

   1 /*
   2  * SHA1 T-PRF for EAP-FAST
   3  * Copyright (c) 2003-2005, 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 "crypto.h"
  20
  21 /**
  22  * sha1_t_prf - EAP-FAST Pseudo-Random Function (T-PRF)
  23  * @key: Key for PRF
  24  * @key_len: Length of the key in bytes
  25  * @label: A unique label for each purpose of the PRF
  26  * @seed: Seed value to bind into the key
  27  * @seed_len: Length of the seed
  28  * @buf: Buffer for the generated pseudo-random key
  29  * @buf_len: Number of bytes of key to generate
  30  * Returns: 0 on success, -1 of failure
  31  *
  32  * This function is used to derive new, cryptographically separate keys from a
  33  * given key for EAP-FAST. T-PRF is defined in RFC 4851, Section 5.5.
  34  */
  35 int sha1_t_prf(const u8 *key, size_t key_len, const char *label,
  36                const u8 *seed, size_t seed_len, u8 *buf, size_t buf_len)
  37 {
  38         unsigned char counter = 0;
  39         size_t pos, plen;
  40         u8 hash[SHA1_MAC_LEN];
  41         size_t label_len = os_strlen(label);
  42         u8 output_len[2];
  43         const unsigned char *addr[5];
  44         size_t len[5];
  45
  46         addr[0] = hash;
  47         len[0] = 0;
  48         addr[1] = (unsigned char *) label;
  49         len[1] = label_len + 1;
  50         addr[2] = seed;
  51         len[2] = seed_len;
  52         addr[3] = output_len;
  53         len[3] = 2;
  54         addr[4] = &counter;
  55         len[4] = 1;
  56
  57         output_len[0] = (buf_len >> 8) & 0xff;
  58         output_len[1] = buf_len & 0xff;
  59         pos = 0;
  60         while (pos < buf_len) {
  61                 counter++;
  62                 plen = buf_len - pos;
  63                 if (hmac_sha1_vector(key, key_len, 5, addr, len, hash))
  64                         return -1;
  65                 if (plen >= SHA1_MAC_LEN) {
  66                         os_memcpy(&buf[pos], hash, SHA1_MAC_LEN);
  67                         pos += SHA1_MAC_LEN;
  68                 } else {
  69                         os_memcpy(&buf[pos], hash, plen);
  70                         break;
  71                 }
  72                 len[0] = SHA1_MAC_LEN;
  73         }
  74
  75         return 0;
  76 }