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 23 int 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