1189251Ssam/* 2189251Ssam * SHA-256 hash implementation and interface functions 3252726Srpaulo * Copyright (c) 2003-2012, Jouni Malinen <j@w1.fi> 4189251Ssam * 5252726Srpaulo * This software may be distributed under the terms of the BSD license. 6252726Srpaulo * See README for more details. 7189251Ssam */ 8189251Ssam 9189251Ssam#include "includes.h" 10189251Ssam 11189251Ssam#include "common.h" 12189251Ssam#include "sha256.h" 13189251Ssam#include "crypto.h" 14189251Ssam 15189251Ssam 16189251Ssam/** 17189251Ssam * hmac_sha256_vector - HMAC-SHA256 over data vector (RFC 2104) 18189251Ssam * @key: Key for HMAC operations 19189251Ssam * @key_len: Length of the key in bytes 20189251Ssam * @num_elem: Number of elements in the data vector 21189251Ssam * @addr: Pointers to the data areas 22189251Ssam * @len: Lengths of the data blocks 23189251Ssam * @mac: Buffer for the hash (32 bytes) 24252726Srpaulo * Returns: 0 on success, -1 on failure 25189251Ssam */ 26252726Srpauloint hmac_sha256_vector(const u8 *key, size_t key_len, size_t num_elem, 27252726Srpaulo const u8 *addr[], const size_t *len, u8 *mac) 28189251Ssam{ 29189251Ssam unsigned char k_pad[64]; /* padding - key XORd with ipad/opad */ 30189251Ssam unsigned char tk[32]; 31189251Ssam const u8 *_addr[6]; 32189251Ssam size_t _len[6], i; 33189251Ssam 34189251Ssam if (num_elem > 5) { 35189251Ssam /* 36189251Ssam * Fixed limit on the number of fragments to avoid having to 37189251Ssam * allocate memory (which could fail). 38189251Ssam */ 39252726Srpaulo return -1; 40189251Ssam } 41189251Ssam 42189251Ssam /* if key is longer than 64 bytes reset it to key = SHA256(key) */ 43189251Ssam if (key_len > 64) { 44252726Srpaulo if (sha256_vector(1, &key, &key_len, tk) < 0) 45252726Srpaulo return -1; 46189251Ssam key = tk; 47189251Ssam key_len = 32; 48189251Ssam } 49189251Ssam 50189251Ssam /* the HMAC_SHA256 transform looks like: 51189251Ssam * 52189251Ssam * SHA256(K XOR opad, SHA256(K XOR ipad, text)) 53189251Ssam * 54189251Ssam * where K is an n byte key 55189251Ssam * ipad is the byte 0x36 repeated 64 times 56189251Ssam * opad is the byte 0x5c repeated 64 times 57189251Ssam * and text is the data being protected */ 58189251Ssam 59189251Ssam /* start out by storing key in ipad */ 60189251Ssam os_memset(k_pad, 0, sizeof(k_pad)); 61189251Ssam os_memcpy(k_pad, key, key_len); 62189251Ssam /* XOR key with ipad values */ 63189251Ssam for (i = 0; i < 64; i++) 64189251Ssam k_pad[i] ^= 0x36; 65189251Ssam 66189251Ssam /* perform inner SHA256 */ 67189251Ssam _addr[0] = k_pad; 68189251Ssam _len[0] = 64; 69189251Ssam for (i = 0; i < num_elem; i++) { 70189251Ssam _addr[i + 1] = addr[i]; 71189251Ssam _len[i + 1] = len[i]; 72189251Ssam } 73252726Srpaulo if (sha256_vector(1 + num_elem, _addr, _len, mac) < 0) 74252726Srpaulo return -1; 75189251Ssam 76189251Ssam os_memset(k_pad, 0, sizeof(k_pad)); 77189251Ssam os_memcpy(k_pad, key, key_len); 78189251Ssam /* XOR key with opad values */ 79189251Ssam for (i = 0; i < 64; i++) 80189251Ssam k_pad[i] ^= 0x5c; 81189251Ssam 82189251Ssam /* perform outer SHA256 */ 83189251Ssam _addr[0] = k_pad; 84189251Ssam _len[0] = 64; 85189251Ssam _addr[1] = mac; 86189251Ssam _len[1] = SHA256_MAC_LEN; 87252726Srpaulo return sha256_vector(2, _addr, _len, mac); 88189251Ssam} 89189251Ssam 90189251Ssam 91189251Ssam/** 92189251Ssam * hmac_sha256 - HMAC-SHA256 over data buffer (RFC 2104) 93189251Ssam * @key: Key for HMAC operations 94189251Ssam * @key_len: Length of the key in bytes 95189251Ssam * @data: Pointers to the data area 96189251Ssam * @data_len: Length of the data area 97252726Srpaulo * @mac: Buffer for the hash (32 bytes) 98252726Srpaulo * Returns: 0 on success, -1 on failure 99189251Ssam */ 100252726Srpauloint hmac_sha256(const u8 *key, size_t key_len, const u8 *data, 101252726Srpaulo size_t data_len, u8 *mac) 102189251Ssam{ 103252726Srpaulo return hmac_sha256_vector(key, key_len, 1, &data, &data_len, mac); 104189251Ssam} 105