2 * FIPS 186-2 PRF for internal crypto implementation
3 * Copyright (c) 2006-2007, Jouni Malinen <j@w1.fi>
5 * This software may be distributed under the terms of the BSD license.
6 * See README for more details.
17 int fips186_2_prf(const u8 *seed, size_t seed_len, u8 *x, size_t xlen)
25 if (seed_len < sizeof(xkey))
26 os_memset(xkey + seed_len, 0, sizeof(xkey) - seed_len);
28 seed_len = sizeof(xkey);
30 /* FIPS 186-2 + change notice 1 */
32 os_memcpy(xkey, seed, seed_len);
40 for (j = 0; j < m; j++) {
42 for (i = 0; i < 2; i++) {
43 /* XVAL = (XKEY + XSEED_j) mod 2^b */
45 /* w_i = G(t, XVAL) */
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);
55 /* XKEY = (1 + XKEY + w_i) mod 2^b */
57 for (k = 19; k >= 0; k--) {
58 carry += xkey[k] + xpos[k];
59 xkey[k] = carry & 0xff;