workbench/network/WirelessManager/src/crypto/sha256.c

   1 /*
   2  * SHA-256 hash implementation and interface functions
   3  * Copyright (c) 2003-2007, 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 "sha256.h"
  19 #include "crypto.h"
  20
  21
  22 /**
  23  * hmac_sha256_vector - HMAC-SHA256 over data vector (RFC 2104)
  24  * @key: Key for HMAC operations
  25  * @key_len: Length of the key in bytes
  26  * @num_elem: Number of elements in the data vector
  27  * @addr: Pointers to the data areas
  28  * @len: Lengths of the data blocks
  29  * @mac: Buffer for the hash (32 bytes)
  30  */
  31 void hmac_sha256_vector(const u8 *key, size_t key_len, size_t num_elem,
  32                         const u8 *addr[], const size_t *len, u8 *mac)
  33 {
  34         unsigned char k_pad[64]; /* padding - key XORd with ipad/opad */
  35         unsigned char tk[32];
  36         const u8 *_addr[6];
  37         size_t _len[6], i;
  38
  39         if (num_elem > 5) {
  40                 /*
  41                  * Fixed limit on the number of fragments to avoid having to
  42                  * allocate memory (which could fail).
  43                  */
  44                 return;
  45         }
  46
  47         /* if key is longer than 64 bytes reset it to key = SHA256(key) */
  48         if (key_len > 64) {
  49                 sha256_vector(1, &key, &key_len, tk);
  50                 key = tk;
  51                 key_len = 32;
  52         }
  53
  54         /* the HMAC_SHA256 transform looks like:
  55          *
  56          * SHA256(K XOR opad, SHA256(K XOR ipad, text))
  57          *
  58          * where K is an n byte key
  59          * ipad is the byte 0x36 repeated 64 times
  60          * opad is the byte 0x5c repeated 64 times
  61          * and text is the data being protected */
  62
  63         /* start out by storing key in ipad */
  64         os_memset(k_pad, 0, sizeof(k_pad));
  65         os_memcpy(k_pad, key, key_len);
  66         /* XOR key with ipad values */
  67         for (i = 0; i < 64; i++)
  68                 k_pad[i] ^= 0x36;
  69
  70         /* perform inner SHA256 */
  71         _addr[0] = k_pad;
  72         _len[0] = 64;
  73         for (i = 0; i < num_elem; i++) {
  74                 _addr[i + 1] = addr[i];
  75                 _len[i + 1] = len[i];
  76         }
  77         sha256_vector(1 + num_elem, _addr, _len, mac);
  78
  79         os_memset(k_pad, 0, sizeof(k_pad));
  80         os_memcpy(k_pad, key, key_len);
  81         /* XOR key with opad values */
  82         for (i = 0; i < 64; i++)
  83                 k_pad[i] ^= 0x5c;
  84
  85         /* perform outer SHA256 */
  86         _addr[0] = k_pad;
  87         _len[0] = 64;
  88         _addr[1] = mac;
  89         _len[1] = SHA256_MAC_LEN;
  90         sha256_vector(2, _addr, _len, mac);
  91 }
  92
  93
  94 /**
  95  * hmac_sha256 - HMAC-SHA256 over data buffer (RFC 2104)
  96  * @key: Key for HMAC operations
  97  * @key_len: Length of the key in bytes
  98  * @data: Pointers to the data area
  99  * @data_len: Length of the data area
 100  * @mac: Buffer for the hash (20 bytes)
 101  */
 102 void hmac_sha256(const u8 *key, size_t key_len, const u8 *data,
 103                  size_t data_len, u8 *mac)
 104 {
 105         hmac_sha256_vector(key, key_len, 1, &data, &data_len, mac);
 106 }
 107
 108
 109 /**
 110  * sha256_prf - SHA256-based Pseudo-Random Function (IEEE 802.11r, 8.5.1.5.2)
 111  * @key: Key for PRF
 112  * @key_len: Length of the key in bytes
 113  * @label: A unique label for each purpose of the PRF
 114  * @data: Extra data to bind into the key
 115  * @data_len: Length of the data
 116  * @buf: Buffer for the generated pseudo-random key
 117  * @buf_len: Number of bytes of key to generate
 118  *
 119  * This function is used to derive new, cryptographically separate keys from a
 120  * given key.
 121  */
 122 void sha256_prf(const u8 *key, size_t key_len, const char *label,
 123                 const u8 *data, size_t data_len, u8 *buf, size_t buf_len)
 124 {
 125         u16 counter = 1;
 126         size_t pos, plen;
 127         u8 hash[SHA256_MAC_LEN];
 128         const u8 *addr[4];
 129         size_t len[4];
 130         u8 counter_le[2], length_le[2];
 131
 132         addr[0] = counter_le;
 133         len[0] = 2;
 134         addr[1] = (u8 *) label;
 135         len[1] = os_strlen(label);
 136         addr[2] = data;
 137         len[2] = data_len;
 138         addr[3] = length_le;
 139         len[3] = sizeof(length_le);
 140
 141         WPA_PUT_LE16(length_le, buf_len * 8);
 142         pos = 0;
 143         while (pos < buf_len) {
 144                 plen = buf_len - pos;
 145                 WPA_PUT_LE16(counter_le, counter);
 146                 if (plen >= SHA256_MAC_LEN) {
 147                         hmac_sha256_vector(key, key_len, 4, addr, len,
 148                                            &buf[pos]);
 149                         pos += SHA256_MAC_LEN;
 150                 } else {
 151                         hmac_sha256_vector(key, key_len, 4, addr, len, hash);
 152                         os_memcpy(&buf[pos], hash, plen);
 153                         break;
 154                 }
 155                 counter++;
 156         }
 157 }