1/*
2 * SHA1 hash implementation and interface functions
3 * Copyright (c) 2003-2005, Jouni Malinen <j@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 "sha1.h"
19#include "crypto.h"
20
21
22/**
23 * hmac_sha1_vector - HMAC-SHA1 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 (20 bytes)
30 * Returns: 0 on success, -1 on failure
31 */
32int hmac_sha1_vector(const u8 *key, size_t key_len, size_t num_elem,
33		     const u8 *addr[], const size_t *len, u8 *mac)
34{
35	unsigned char k_pad[64]; /* padding - key XORd with ipad/opad */
36	unsigned char tk[20];
37	const u8 *_addr[6];
38	size_t _len[6], i;
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 = SHA1(key) */
49        if (key_len > 64) {
50		if (sha1_vector(1, &key, &key_len, tk))
51			return -1;
52		key = tk;
53		key_len = 20;
54        }
55
56	/* the HMAC_SHA1 transform looks like:
57	 *
58	 * SHA1(K XOR opad, SHA1(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	/* XOR key with ipad values */
69	for (i = 0; i < 64; i++)
70		k_pad[i] ^= 0x36;
71
72	/* perform inner SHA1 */
73	_addr[0] = k_pad;
74	_len[0] = 64;
75	for (i = 0; i < num_elem; i++) {
76		_addr[i + 1] = addr[i];
77		_len[i + 1] = len[i];
78	}
79	if (sha1_vector(1 + num_elem, _addr, _len, mac))
80		return -1;
81
82	os_memset(k_pad, 0, sizeof(k_pad));
83	os_memcpy(k_pad, key, key_len);
84	/* XOR key with opad values */
85	for (i = 0; i < 64; i++)
86		k_pad[i] ^= 0x5c;
87
88	/* perform outer SHA1 */
89	_addr[0] = k_pad;
90	_len[0] = 64;
91	_addr[1] = mac;
92	_len[1] = SHA1_MAC_LEN;
93	return sha1_vector(2, _addr, _len, mac);
94}
95
96
97/**
98 * hmac_sha1 - HMAC-SHA1 over data buffer (RFC 2104)
99 * @key: Key for HMAC operations
100 * @key_len: Length of the key in bytes
101 * @data: Pointers to the data area
102 * @data_len: Length of the data area
103 * @mac: Buffer for the hash (20 bytes)
104 * Returns: 0 on success, -1 of failure
105 */
106int hmac_sha1(const u8 *key, size_t key_len, const u8 *data, size_t data_len,
107	       u8 *mac)
108{
109	return hmac_sha1_vector(key, key_len, 1, &data, &data_len, mac);
110}
111
112
113/**
114 * sha1_prf - SHA1-based Pseudo-Random Function (PRF) (IEEE 802.11i, 8.5.1.1)
115 * @key: Key for PRF
116 * @key_len: Length of the key in bytes
117 * @label: A unique label for each purpose of the PRF
118 * @data: Extra data to bind into the key
119 * @data_len: Length of the data
120 * @buf: Buffer for the generated pseudo-random key
121 * @buf_len: Number of bytes of key to generate
122 * Returns: 0 on success, -1 of failure
123 *
124 * This function is used to derive new, cryptographically separate keys from a
125 * given key (e.g., PMK in IEEE 802.11i).
126 */
127int sha1_prf(const u8 *key, size_t key_len, const char *label,
128	     const u8 *data, size_t data_len, u8 *buf, size_t buf_len)
129{
130	u8 counter = 0;
131	size_t pos, plen;
132	u8 hash[SHA1_MAC_LEN];
133	size_t label_len = os_strlen(label) + 1;
134	const unsigned char *addr[3];
135	size_t len[3];
136
137	addr[0] = (u8 *) label;
138	len[0] = label_len;
139	addr[1] = data;
140	len[1] = data_len;
141	addr[2] = &counter;
142	len[2] = 1;
143
144	pos = 0;
145	while (pos < buf_len) {
146		plen = buf_len - pos;
147		if (plen >= SHA1_MAC_LEN) {
148			if (hmac_sha1_vector(key, key_len, 3, addr, len,
149					     &buf[pos]))
150				return -1;
151			pos += SHA1_MAC_LEN;
152		} else {
153			if (hmac_sha1_vector(key, key_len, 3, addr, len,
154					     hash))
155				return -1;
156			os_memcpy(&buf[pos], hash, plen);
157			break;
158		}
159		counter++;
160	}
161
162	return 0;
163}
164