1/*
2 * FIPS 186-2 PRF for libcrypto
3 * Copyright (c) 2004-2005, 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#include <openssl/sha.h>
11
12#include "common.h"
13#include "crypto.h"
14
15
16static void sha1_transform(u8 *state, const u8 data[64])
17{
18	SHA_CTX context;
19	os_memset(&context, 0, sizeof(context));
20	os_memcpy(&context.h0, state, 5 * 4);
21	SHA1_Transform(&context, data);
22	os_memcpy(state, &context.h0, 5 * 4);
23}
24
25
26int fips186_2_prf(const u8 *seed, size_t seed_len, u8 *x, size_t xlen)
27{
28	u8 xkey[64];
29	u32 t[5], _t[5];
30	int i, j, m, k;
31	u8 *xpos = x;
32	u32 carry;
33
34	if (seed_len < sizeof(xkey))
35		os_memset(xkey + seed_len, 0, sizeof(xkey) - seed_len);
36	else
37		seed_len = sizeof(xkey);
38
39	/* FIPS 186-2 + change notice 1 */
40
41	os_memcpy(xkey, seed, seed_len);
42	t[0] = 0x67452301;
43	t[1] = 0xEFCDAB89;
44	t[2] = 0x98BADCFE;
45	t[3] = 0x10325476;
46	t[4] = 0xC3D2E1F0;
47
48	m = xlen / 40;
49	for (j = 0; j < m; j++) {
50		/* XSEED_j = 0 */
51		for (i = 0; i < 2; i++) {
52			/* XVAL = (XKEY + XSEED_j) mod 2^b */
53
54			/* w_i = G(t, XVAL) */
55			os_memcpy(_t, t, 20);
56			sha1_transform((u8 *) _t, xkey);
57			_t[0] = host_to_be32(_t[0]);
58			_t[1] = host_to_be32(_t[1]);
59			_t[2] = host_to_be32(_t[2]);
60			_t[3] = host_to_be32(_t[3]);
61			_t[4] = host_to_be32(_t[4]);
62			os_memcpy(xpos, _t, 20);
63
64			/* XKEY = (1 + XKEY + w_i) mod 2^b */
65			carry = 1;
66			for (k = 19; k >= 0; k--) {
67				carry += xkey[k] + xpos[k];
68				xkey[k] = carry & 0xff;
69				carry >>= 8;
70			}
71
72			xpos += 20;
73		}
74		/* x_j = w_0|w_1 */
75	}
76
77	return 0;
78}
79