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
fips186_2_prf(const u8 * seed,size_t seed_len,u8 * x,size_t xlen)17 int 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
