sha1-tprf.c revision 214501
1214501Srpaulo/* 2214501Srpaulo * SHA1 T-PRF for EAP-FAST 3214501Srpaulo * Copyright (c) 2003-2005, Jouni Malinen <j@w1.fi> 4214501Srpaulo * 5214501Srpaulo * This program is free software; you can redistribute it and/or modify 6214501Srpaulo * it under the terms of the GNU General Public License version 2 as 7214501Srpaulo * published by the Free Software Foundation. 8214501Srpaulo * 9214501Srpaulo * Alternatively, this software may be distributed under the terms of BSD 10214501Srpaulo * license. 11214501Srpaulo * 12214501Srpaulo * See README and COPYING for more details. 13214501Srpaulo */ 14214501Srpaulo 15214501Srpaulo#include "includes.h" 16214501Srpaulo 17214501Srpaulo#include "common.h" 18214501Srpaulo#include "sha1.h" 19214501Srpaulo#include "crypto.h" 20214501Srpaulo 21214501Srpaulo/** 22214501Srpaulo * sha1_t_prf - EAP-FAST Pseudo-Random Function (T-PRF) 23214501Srpaulo * @key: Key for PRF 24214501Srpaulo * @key_len: Length of the key in bytes 25214501Srpaulo * @label: A unique label for each purpose of the PRF 26214501Srpaulo * @seed: Seed value to bind into the key 27214501Srpaulo * @seed_len: Length of the seed 28214501Srpaulo * @buf: Buffer for the generated pseudo-random key 29214501Srpaulo * @buf_len: Number of bytes of key to generate 30214501Srpaulo * Returns: 0 on success, -1 of failure 31214501Srpaulo * 32214501Srpaulo * This function is used to derive new, cryptographically separate keys from a 33214501Srpaulo * given key for EAP-FAST. T-PRF is defined in RFC 4851, Section 5.5. 34214501Srpaulo */ 35214501Srpauloint sha1_t_prf(const u8 *key, size_t key_len, const char *label, 36214501Srpaulo const u8 *seed, size_t seed_len, u8 *buf, size_t buf_len) 37214501Srpaulo{ 38214501Srpaulo unsigned char counter = 0; 39214501Srpaulo size_t pos, plen; 40214501Srpaulo u8 hash[SHA1_MAC_LEN]; 41214501Srpaulo size_t label_len = os_strlen(label); 42214501Srpaulo u8 output_len[2]; 43214501Srpaulo const unsigned char *addr[5]; 44214501Srpaulo size_t len[5]; 45214501Srpaulo 46214501Srpaulo addr[0] = hash; 47214501Srpaulo len[0] = 0; 48214501Srpaulo addr[1] = (unsigned char *) label; 49214501Srpaulo len[1] = label_len + 1; 50214501Srpaulo addr[2] = seed; 51214501Srpaulo len[2] = seed_len; 52214501Srpaulo addr[3] = output_len; 53214501Srpaulo len[3] = 2; 54214501Srpaulo addr[4] = &counter; 55214501Srpaulo len[4] = 1; 56214501Srpaulo 57214501Srpaulo output_len[0] = (buf_len >> 8) & 0xff; 58214501Srpaulo output_len[1] = buf_len & 0xff; 59214501Srpaulo pos = 0; 60214501Srpaulo while (pos < buf_len) { 61214501Srpaulo counter++; 62214501Srpaulo plen = buf_len - pos; 63214501Srpaulo if (hmac_sha1_vector(key, key_len, 5, addr, len, hash)) 64214501Srpaulo return -1; 65214501Srpaulo if (plen >= SHA1_MAC_LEN) { 66214501Srpaulo os_memcpy(&buf[pos], hash, SHA1_MAC_LEN); 67214501Srpaulo pos += SHA1_MAC_LEN; 68214501Srpaulo } else { 69214501Srpaulo os_memcpy(&buf[pos], hash, plen); 70214501Srpaulo break; 71214501Srpaulo } 72214501Srpaulo len[0] = SHA1_MAC_LEN; 73214501Srpaulo } 74214501Srpaulo 75214501Srpaulo return 0; 76214501Srpaulo} 77