1/*
2 * FIPS 186-2 PRF for internal crypto implementation
3 * Copyright (c) 2006-2007, 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 "sha1_i.h"
14#include "crypto.h"
15
16
17int fips186_2_prf(const u8 *seed, size_t seed_len, u8 *x, size_t xlen)
18{
19	u8 xkey[64];
20	u32 t[5], _t[5];
21	int i, j, m, k;
22	u8 *xpos = x;
23	u32 carry;
24
25	if (seed_len < sizeof(xkey))
26		os_memset(xkey + seed_len, 0, sizeof(xkey) - seed_len);
27	else
28		seed_len = sizeof(xkey);
29
30	/* FIPS 186-2 + change notice 1 */
31
32	os_memcpy(xkey, seed, seed_len);
33	t[0] = 0x67452301;
34	t[1] = 0xEFCDAB89;
35	t[2] = 0x98BADCFE;
36	t[3] = 0x10325476;
37	t[4] = 0xC3D2E1F0;
38
39	m = xlen / 40;
40	for (j = 0; j < m; j++) {
41		/* XSEED_j = 0 */
42		for (i = 0; i < 2; i++) {
43			/* XVAL = (XKEY + XSEED_j) mod 2^b */
44
45			/* w_i = G(t, XVAL) */
46			os_memcpy(_t, t, 20);
47			SHA1Transform(_t, xkey);
48			_t[0] = host_to_be32(_t[0]);
49			_t[1] = host_to_be32(_t[1]);
50			_t[2] = host_to_be32(_t[2]);
51			_t[3] = host_to_be32(_t[3]);
52			_t[4] = host_to_be32(_t[4]);
53			os_memcpy(xpos, _t, 20);
54
55			/* XKEY = (1 + XKEY + w_i) mod 2^b */
56			carry = 1;
57			for (k = 19; k >= 0; k--) {
58				carry += xkey[k] + xpos[k];
59				xkey[k] = carry & 0xff;
60				carry >>= 8;
61			}
62
63			xpos += SHA1_MAC_LEN;
64		}
65		/* x_j = w_0|w_1 */
66	}
67
68	return 0;
69}
70