1 /* 2 * SHA-256 hash implementation and interface functions 3 * Copyright (c) 2003-2012, 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 "sha256.h" 13 #include "crypto.h" 14 15 16 /** 17 * hmac_sha256_vector - HMAC-SHA256 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 (32 bytes) 24 * Returns: 0 on success, -1 on failure 25 */ 26 int hmac_sha256_vector(const u8 *key, size_t key_len, size_t num_elem, 27 const u8 *addr[], const size_t *len, u8 *mac) 28 { 29 unsigned char k_pad[64]; /* padding - key XORd with ipad/opad */ 30 unsigned char tk[32]; 31 const u8 *_addr[11]; 32 size_t _len[11], i; 33 34 if (num_elem > 10) { 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 = SHA256(key) */ 43 if (key_len > 64) { 44 if (sha256_vector(1, &key, &key_len, tk) < 0) 45 return -1; 46 key = tk; 47 key_len = 32; 48 } 49 50 /* the HMAC_SHA256 transform looks like: 51 * 52 * SHA256(K XOR opad, SHA256(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 /* XOR key with ipad values */ 63 for (i = 0; i < 64; i++) 64 k_pad[i] ^= 0x36; 65 66 /* perform inner SHA256 */ 67 _addr[0] = k_pad; 68 _len[0] = 64; 69 for (i = 0; i < num_elem; i++) { 70 _addr[i + 1] = addr[i]; 71 _len[i + 1] = len[i]; 72 } 73 if (sha256_vector(1 + num_elem, _addr, _len, mac) < 0) 74 return -1; 75 76 os_memset(k_pad, 0, sizeof(k_pad)); 77 os_memcpy(k_pad, key, key_len); 78 /* XOR key with opad values */ 79 for (i = 0; i < 64; i++) 80 k_pad[i] ^= 0x5c; 81 82 /* perform outer SHA256 */ 83 _addr[0] = k_pad; 84 _len[0] = 64; 85 _addr[1] = mac; 86 _len[1] = SHA256_MAC_LEN; 87 return sha256_vector(2, _addr, _len, mac); 88 } 89 90 91 /** 92 * hmac_sha256 - HMAC-SHA256 over data buffer (RFC 2104) 93 * @key: Key for HMAC operations 94 * @key_len: Length of the key in bytes 95 * @data: Pointers to the data area 96 * @data_len: Length of the data area 97 * @mac: Buffer for the hash (32 bytes) 98 * Returns: 0 on success, -1 on failure 99 */ 100 int hmac_sha256(const u8 *key, size_t key_len, const u8 *data, 101 size_t data_len, u8 *mac) 102 { 103 return hmac_sha256_vector(key, key_len, 1, &data, &data_len, mac); 104 } 105