1/*
2 * Crypto wrapper for internal crypto implementation - modexp
3 * Copyright (c) 2006-2009, 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 "tls/bignum.h"
19#include "crypto.h"
20
21
22int crypto_mod_exp(const u8 *base, size_t base_len,
23		   const u8 *power, size_t power_len,
24		   const u8 *modulus, size_t modulus_len,
25		   u8 *result, size_t *result_len)
26{
27	struct bignum *bn_base, *bn_exp, *bn_modulus, *bn_result;
28	int ret = -1;
29
30	bn_base = bignum_init();
31	bn_exp = bignum_init();
32	bn_modulus = bignum_init();
33	bn_result = bignum_init();
34
35	if (bn_base == NULL || bn_exp == NULL || bn_modulus == NULL ||
36	    bn_result == NULL)
37		goto error;
38
39	if (bignum_set_unsigned_bin(bn_base, base, base_len) < 0 ||
40	    bignum_set_unsigned_bin(bn_exp, power, power_len) < 0 ||
41	    bignum_set_unsigned_bin(bn_modulus, modulus, modulus_len) < 0)
42		goto error;
43
44	if (bignum_exptmod(bn_base, bn_exp, bn_modulus, bn_result) < 0)
45		goto error;
46
47	ret = bignum_get_unsigned_bin(bn_result, result, result_len);
48
49error:
50	bignum_deinit(bn_base);
51	bignum_deinit(bn_exp);
52	bignum_deinit(bn_modulus);
53	bignum_deinit(bn_result);
54	return ret;
55}
56