1 /* 2 * MD5 hash implementation and interface functions 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 "md5.h" 13 #include "crypto.h" 14 15 16 /** 17 * hmac_md5_vector - HMAC-MD5 over data vector (RFC 2104) 18 * @key: Key for HMAC operations 19 * @key_len: Length of the key in bytes 20 * @num_elem: Number of elements in the data vector 21 * @addr: Pointers to the data areas 22 * @len: Lengths of the data blocks 23 * @mac: Buffer for the hash (16 bytes) 24 * Returns: 0 on success, -1 on failure 25 */ 26 int hmac_md5_vector(const u8 *key, size_t key_len, size_t num_elem, 27 const u8 *addr[], const size_t *len, u8 *mac) 28 { 29 u8 k_pad[64]; /* padding - key XORd with ipad/opad */ 30 u8 tk[16]; 31 const u8 *_addr[6]; 32 size_t i, _len[6]; 33 34 if (num_elem > 5) { 35 /* 36 * Fixed limit on the number of fragments to avoid having to 37 * allocate memory (which could fail). 38 */ 39 return -1; 40 } 41 42 /* if key is longer than 64 bytes reset it to key = MD5(key) */ 43 if (key_len > 64) { 44 if (md5_vector(1, &key, &key_len, tk)) 45 return -1; 46 key = tk; 47 key_len = 16; 48 } 49 50 /* the HMAC_MD5 transform looks like: 51 * 52 * MD5(K XOR opad, MD5(K XOR ipad, text)) 53 * 54 * where K is an n byte key 55 * ipad is the byte 0x36 repeated 64 times 56 * opad is the byte 0x5c repeated 64 times 57 * and text is the data being protected */ 58 59 /* start out by storing key in ipad */ 60 os_memset(k_pad, 0, sizeof(k_pad)); 61 os_memcpy(k_pad, key, key_len); 62 63 /* XOR key with ipad values */ 64 for (i = 0; i < 64; i++) 65 k_pad[i] ^= 0x36; 66 67 /* perform inner MD5 */ 68 _addr[0] = k_pad; 69 _len[0] = 64; 70 for (i = 0; i < num_elem; i++) { 71 _addr[i + 1] = addr[i]; 72 _len[i + 1] = len[i]; 73 } 74 if (md5_vector(1 + num_elem, _addr, _len, mac)) 75 return -1; 76 77 os_memset(k_pad, 0, sizeof(k_pad)); 78 os_memcpy(k_pad, key, key_len); 79 /* XOR key with opad values */ 80 for (i = 0; i < 64; i++) 81 k_pad[i] ^= 0x5c; 82 83 /* perform outer MD5 */ 84 _addr[0] = k_pad; 85 _len[0] = 64; 86 _addr[1] = mac; 87 _len[1] = MD5_MAC_LEN; 88 return md5_vector(2, _addr, _len, mac); 89 } 90 91 92 /** 93 * hmac_md5 - HMAC-MD5 over data buffer (RFC 2104) 94 * @key: Key for HMAC operations 95 * @key_len: Length of the key in bytes 96 * @data: Pointers to the data area 97 * @data_len: Length of the data area 98 * @mac: Buffer for the hash (16 bytes) 99 * Returns: 0 on success, -1 on failure 100 */ 101 int hmac_md5(const u8 *key, size_t key_len, const u8 *data, size_t data_len, 102 u8 *mac) 103 { 104 return hmac_md5_vector(key, key_len, 1, &data, &data_len, mac); 105 } 106