1 /*
2 * SHA1-based PRF
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 * sha1_prf - SHA1-based Pseudo-Random Function (PRF) (IEEE 802.11i, 8.5.1.1)
18 * @key: Key for PRF
19 * @key_len: Length of the key in bytes
20 * @label: A unique label for each purpose of the PRF
21 * @data: Extra data to bind into the key
22 * @data_len: Length of the data
23 * @buf: Buffer for the generated pseudo-random key
24 * @buf_len: Number of bytes of key to generate
25 * Returns: 0 on success, -1 of failure
26 *
27 * This function is used to derive new, cryptographically separate keys from a
28 * given key (e.g., PMK in IEEE 802.11i).
29 */
sha1_prf(const u8 * key,size_t key_len,const char * label,const u8 * data,size_t data_len,u8 * buf,size_t buf_len)30 int sha1_prf(const u8 *key, size_t key_len, const char *label,
31 const u8 *data, size_t data_len, u8 *buf, size_t buf_len)
32 {
33 u8 counter = 0;
34 size_t pos, plen;
35 u8 hash[SHA1_MAC_LEN];
36 size_t label_len = os_strlen(label) + 1;
37 const unsigned char *addr[3];
38 size_t len[3];
39
40 addr[0] = (u8 *) label;
41 len[0] = label_len;
42 addr[1] = data;
43 len[1] = data_len;
44 addr[2] = &counter;
45 len[2] = 1;
46
47 pos = 0;
48 while (pos < buf_len) {
49 plen = buf_len - pos;
50 if (plen >= SHA1_MAC_LEN) {
51 if (hmac_sha1_vector(key, key_len, 3, addr, len,
52 &buf[pos]))
53 return -1;
54 pos += SHA1_MAC_LEN;
55 } else {
56 if (hmac_sha1_vector(key, key_len, 3, addr, len,
57 hash))
58 return -1;
59 os_memcpy(&buf[pos], hash, plen);
60 break;
61 }
62 counter++;
63 }
64 forced_memzero(hash, sizeof(hash));
65
66 return 0;
67 }
68
