1 /* 2 * SHA1 hash implementation and interface functions 3 * Copyright (c) 2003-2005, Jouni Malinen <j (at) 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 /** 23 * hmac_sha1_vector - HMAC-SHA1 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 (20 bytes) 30 * Returns: 0 on success, -1 on failure 31 */ 32 int hmac_sha1_vector(const u8 *key, size_t key_len, size_t num_elem, 33 const u8 *addr[], const size_t *len, u8 *mac) 34 { 35 unsigned char k_pad[64]; /* padding - key XORd with ipad/opad */ 36 unsigned char tk[20]; 37 const u8 *_addr[6]; 38 size_t _len[6], i; 39 40 if (num_elem > 5) { 41 /* 42 * Fixed limit on the number of fragments to avoid having to 43 * allocate memory (which could fail). 44 */ 45 return -1; 46 } 47 48 /* if key is longer than 64 bytes reset it to key = SHA1(key) */ 49 if (key_len > 64) { 50 if (sha1_vector(1, &key, &key_len, tk)) 51 return -1; 52 key = tk; 53 key_len = 20; 54 } 55 56 /* the HMAC_SHA1 transform looks like: 57 * 58 * SHA1(K XOR opad, SHA1(K XOR ipad, text)) 59 * 60 * where K is an n byte key 61 * ipad is the byte 0x36 repeated 64 times 62 * opad is the byte 0x5c repeated 64 times 63 * and text is the data being protected */ 64 65 /* start out by storing key in ipad */ 66 os_memset(k_pad, 0, sizeof(k_pad)); 67 os_memcpy(k_pad, key, key_len); 68 /* XOR key with ipad values */ 69 for (i = 0; i < 64; i++) 70 k_pad[i] ^= 0x36; 71 72 /* perform inner SHA1 */ 73 _addr[0] = k_pad; 74 _len[0] = 64; 75 for (i = 0; i < num_elem; i++) { 76 _addr[i + 1] = addr[i]; 77 _len[i + 1] = len[i]; 78 } 79 if (sha1_vector(1 + num_elem, _addr, _len, mac)) 80 return -1; 81 82 os_memset(k_pad, 0, sizeof(k_pad)); 83 os_memcpy(k_pad, key, key_len); 84 /* XOR key with opad values */ 85 for (i = 0; i < 64; i++) 86 k_pad[i] ^= 0x5c; 87 88 /* perform outer SHA1 */ 89 _addr[0] = k_pad; 90 _len[0] = 64; 91 _addr[1] = mac; 92 _len[1] = SHA1_MAC_LEN; 93 return sha1_vector(2, _addr, _len, mac); 94 } 95 96 97 /** 98 * hmac_sha1 - HMAC-SHA1 over data buffer (RFC 2104) 99 * @key: Key for HMAC operations 100 * @key_len: Length of the key in bytes 101 * @data: Pointers to the data area 102 * @data_len: Length of the data area 103 * @mac: Buffer for the hash (20 bytes) 104 * Returns: 0 on success, -1 of failure 105 */ 106 int hmac_sha1(const u8 *key, size_t key_len, const u8 *data, size_t data_len, 107 u8 *mac) 108 { 109 return hmac_sha1_vector(key, key_len, 1, &data, &data_len, mac); 110 } 111 112 113 /** 114 * sha1_prf - SHA1-based Pseudo-Random Function (PRF) (IEEE 802.11i, 8.5.1.1) 115 * @key: Key for PRF 116 * @key_len: Length of the key in bytes 117 * @label: A unique label for each purpose of the PRF 118 * @data: Extra data to bind into the key 119 * @data_len: Length of the data 120 * @buf: Buffer for the generated pseudo-random key 121 * @buf_len: Number of bytes of key to generate 122 * Returns: 0 on success, -1 of failure 123 * 124 * This function is used to derive new, cryptographically separate keys from a 125 * given key (e.g., PMK in IEEE 802.11i). 126 */ 127 int sha1_prf(const u8 *key, size_t key_len, const char *label, 128 const u8 *data, size_t data_len, u8 *buf, size_t buf_len) 129 { 130 u8 counter = 0; 131 size_t pos, plen; 132 u8 hash[SHA1_MAC_LEN]; 133 size_t label_len = os_strlen(label) + 1; 134 const unsigned char *addr[3]; 135 size_t len[3]; 136 137 addr[0] = (u8 *) label; 138 len[0] = label_len; 139 addr[1] = data; 140 len[1] = data_len; 141 addr[2] = &counter; 142 len[2] = 1; 143 144 pos = 0; 145 while (pos < buf_len) { 146 plen = buf_len - pos; 147 if (plen >= SHA1_MAC_LEN) { 148 if (hmac_sha1_vector(key, key_len, 3, addr, len, 149 &buf[pos])) 150 return -1; 151 pos += SHA1_MAC_LEN; 152 } else { 153 if (hmac_sha1_vector(key, key_len, 3, addr, len, 154 hash)) 155 return -1; 156 os_memcpy(&buf[pos], hash, plen); 157 break; 158 } 159 counter++; 160 } 161 162 return 0; 163 } 164
