1 /* 2 * SHA1-based PRF 3 * Copyright (c) 2003-2005, 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 "sha1.h" 13 #include "crypto.h" 14 15 16 /** 17 * sha1_prf - SHA1-based Pseudo-Random Function (PRF) (IEEE 802.11i, 8.5.1.1) 18 * @key: Key for PRF 19 * @key_len: Length of the key in bytes 20 * @label: A unique label for each purpose of the PRF 21 * @data: Extra data to bind into the key 22 * @data_len: Length of the data 23 * @buf: Buffer for the generated pseudo-random key 24 * @buf_len: Number of bytes of key to generate 25 * Returns: 0 on success, -1 of failure 26 * 27 * This function is used to derive new, cryptographically separate keys from a 28 * given key (e.g., PMK in IEEE 802.11i). 29 */ 30 int sha1_prf(const u8 *key, size_t key_len, const char *label, 31 const u8 *data, size_t data_len, u8 *buf, size_t buf_len) 32 { 33 u8 counter = 0; 34 size_t pos, plen; 35 u8 hash[SHA1_MAC_LEN]; 36 size_t label_len = os_strlen(label) + 1; 37 const unsigned char *addr[3]; 38 size_t len[3]; 39 40 addr[0] = (u8 *) label; 41 len[0] = label_len; 42 addr[1] = data; 43 len[1] = data_len; 44 addr[2] = &counter; 45 len[2] = 1; 46 47 pos = 0; 48 while (pos < buf_len) { 49 plen = buf_len - pos; 50 if (plen >= SHA1_MAC_LEN) { 51 if (hmac_sha1_vector(key, key_len, 3, addr, len, 52 &buf[pos])) 53 return -1; 54 pos += SHA1_MAC_LEN; 55 } else { 56 if (hmac_sha1_vector(key, key_len, 3, addr, len, 57 hash)) 58 return -1; 59 os_memcpy(&buf[pos], hash, plen); 60 break; 61 } 62 counter++; 63 } 64 os_memset(hash, 0, sizeof(hash)); 65 66 return 0; 67 } 68