1 /* 2 * MD5 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 "md5.h" 19 #include "crypto.h" 20 21 22 /** 23 * hmac_md5_vector - HMAC-MD5 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 (16 bytes) 30 * Returns: 0 on success, -1 on failure 31 */ 32 int hmac_md5_vector(const u8 *key, size_t key_len, size_t num_elem, 33 const u8 *addr[], const size_t *len, u8 *mac) 34 { 35 u8 k_pad[64]; /* padding - key XORd with ipad/opad */ 36 u8 tk[16]; 37 const u8 *_addr[6]; 38 size_t i, _len[6]; 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 = MD5(key) */ 49 if (key_len > 64) { 50 if (md5_vector(1, &key, &key_len, tk)) 51 return -1; 52 key = tk; 53 key_len = 16; 54 } 55 56 /* the HMAC_MD5 transform looks like: 57 * 58 * MD5(K XOR opad, MD5(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 69 /* XOR key with ipad values */ 70 for (i = 0; i < 64; i++) 71 k_pad[i] ^= 0x36; 72 73 /* perform inner MD5 */ 74 _addr[0] = k_pad; 75 _len[0] = 64; 76 for (i = 0; i < num_elem; i++) { 77 _addr[i + 1] = addr[i]; 78 _len[i + 1] = len[i]; 79 } 80 if (md5_vector(1 + num_elem, _addr, _len, mac)) 81 return -1; 82 83 os_memset(k_pad, 0, sizeof(k_pad)); 84 os_memcpy(k_pad, key, key_len); 85 /* XOR key with opad values */ 86 for (i = 0; i < 64; i++) 87 k_pad[i] ^= 0x5c; 88 89 /* perform outer MD5 */ 90 _addr[0] = k_pad; 91 _len[0] = 64; 92 _addr[1] = mac; 93 _len[1] = MD5_MAC_LEN; 94 return md5_vector(2, _addr, _len, mac); 95 } 96 97 98 /** 99 * hmac_md5 - HMAC-MD5 over data buffer (RFC 2104) 100 * @key: Key for HMAC operations 101 * @key_len: Length of the key in bytes 102 * @data: Pointers to the data area 103 * @data_len: Length of the data area 104 * @mac: Buffer for the hash (16 bytes) 105 * Returns: 0 on success, -1 on failure 106 */ 107 int hmac_md5(const u8 *key, size_t key_len, const u8 *data, size_t data_len, 108 u8 *mac) 109 { 110 return hmac_md5_vector(key, key_len, 1, &data, &data_len, mac); 111 } 112
