fips_prf_internal.c revision 214734 
1/*
2 * FIPS 186-2 PRF for internal crypto implementation
3 * Copyright (c) 2006-2007, 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 "sha1_i.h"
20#include "crypto.h"
21
22
23int fips186_2_prf(const u8 *seed, size_t seed_len, u8 *x, size_t xlen)
24{
25	u8 xkey[64];
26	u32 t[5], _t[5];
27	int i, j, m, k;
28	u8 *xpos = x;
29	u32 carry;
30
31	if (seed_len > sizeof(xkey))
32		seed_len = sizeof(xkey);
33
34	/* FIPS 186-2 + change notice 1 */
35
36	os_memcpy(xkey, seed, seed_len);
37	os_memset(xkey + seed_len, 0, 64 - seed_len);
38	t[0] = 0x67452301;
39	t[1] = 0xEFCDAB89;
40	t[2] = 0x98BADCFE;
41	t[3] = 0x10325476;
42	t[4] = 0xC3D2E1F0;
43
44	m = xlen / 40;
45	for (j = 0; j < m; j++) {
46		/* XSEED_j = 0 */
47		for (i = 0; i < 2; i++) {
48			/* XVAL = (XKEY + XSEED_j) mod 2^b */
49
50			/* w_i = G(t, XVAL) */
51			os_memcpy(_t, t, 20);
52			SHA1Transform(_t, xkey);
53			_t[0] = host_to_be32(_t[0]);
54			_t[1] = host_to_be32(_t[1]);
55			_t[2] = host_to_be32(_t[2]);
56			_t[3] = host_to_be32(_t[3]);
57			_t[4] = host_to_be32(_t[4]);
58			os_memcpy(xpos, _t, 20);
59
60			/* XKEY = (1 + XKEY + w_i) mod 2^b */
61			carry = 1;
62			for (k = 19; k >= 0; k--) {
63				carry += xkey[k] + xpos[k];
64				xkey[k] = carry & 0xff;
65				carry >>= 8;
66			}
67
68			xpos += SHA1_MAC_LEN;
69		}
70		/* x_j = w_0|w_1 */
71	}
72
73	return 0;
74}
75