sha1.c revision c5ec7f57ead87efa365800228aa0b09a12d9e6c4 
1/*
2 * SHA1 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 "sha1.h"
13#include "crypto.h"
14
15
16/**
17 * hmac_sha1_vector - HMAC-SHA1 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 (20 bytes)
24 * Returns: 0 on success, -1 on failure
25 */
26int hmac_sha1_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[20];
31	const u8 *_addr[6];
32	size_t _len[6], i;
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 = SHA1(key) */
43        if (key_len > 64) {
44		if (sha1_vector(1, &key, &key_len, tk))
45			return -1;
46		key = tk;
47		key_len = 20;
48        }
49
50	/* the HMAC_SHA1 transform looks like:
51	 *
52	 * SHA1(K XOR opad, SHA1(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 SHA1 */
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 (sha1_vector(1 + num_elem, _addr, _len, mac))
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 SHA1 */
83	_addr[0] = k_pad;
84	_len[0] = 64;
85	_addr[1] = mac;
86	_len[1] = SHA1_MAC_LEN;
87	return sha1_vector(2, _addr, _len, mac);
88}
89
90
91/**
92 * hmac_sha1 - HMAC-SHA1 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 (20 bytes)
98 * Returns: 0 on success, -1 of failure
99 */
100int hmac_sha1(const u8 *key, size_t key_len, const u8 *data, size_t data_len,
101	       u8 *mac)
102{
103	return hmac_sha1_vector(key, key_len, 1, &data, &data_len, mac);
104}
105
106
107/**
108 * sha1_prf - SHA1-based Pseudo-Random Function (PRF) (IEEE 802.11i, 8.5.1.1)
109 * @key: Key for PRF
110 * @key_len: Length of the key in bytes
111 * @label: A unique label for each purpose of the PRF
112 * @data: Extra data to bind into the key
113 * @data_len: Length of the data
114 * @buf: Buffer for the generated pseudo-random key
115 * @buf_len: Number of bytes of key to generate
116 * Returns: 0 on success, -1 of failure
117 *
118 * This function is used to derive new, cryptographically separate keys from a
119 * given key (e.g., PMK in IEEE 802.11i).
120 */
121int sha1_prf(const u8 *key, size_t key_len, const char *label,
122	     const u8 *data, size_t data_len, u8 *buf, size_t buf_len)
123{
124	u8 counter = 0;
125	size_t pos, plen;
126	u8 hash[SHA1_MAC_LEN];
127	size_t label_len = os_strlen(label) + 1;
128	const unsigned char *addr[3];
129	size_t len[3];
130
131	addr[0] = (u8 *) label;
132	len[0] = label_len;
133	addr[1] = data;
134	len[1] = data_len;
135	addr[2] = &counter;
136	len[2] = 1;
137
138	pos = 0;
139	while (pos < buf_len) {
140		plen = buf_len - pos;
141		if (plen >= SHA1_MAC_LEN) {
142			if (hmac_sha1_vector(key, key_len, 3, addr, len,
143					     &buf[pos]))
144				return -1;
145			pos += SHA1_MAC_LEN;
146		} else {
147			if (hmac_sha1_vector(key, key_len, 3, addr, len,
148					     hash))
149				return -1;
150			os_memcpy(&buf[pos], hash, plen);
151			break;
152		}
153		counter++;
154	}
155
156	return 0;
157}
158