1 /*
2  * Crypto wrapper for internal crypto implementation - modexp
3  * Copyright (c) 2006-2009, 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 "tls/bignum.h"
13 #include "crypto.h"
14 
15 
16 int crypto_mod_exp(const u8 *base, size_t base_len,
17 		   const u8 *power, size_t power_len,
18 		   const u8 *modulus, size_t modulus_len,
19 		   u8 *result, size_t *result_len)
20 {
21 	struct bignum *bn_base, *bn_exp, *bn_modulus, *bn_result;
22 	int ret = -1;
23 
24 	bn_base = bignum_init();
25 	bn_exp = bignum_init();
26 	bn_modulus = bignum_init();
27 	bn_result = bignum_init();
28 
29 	if (bn_base == NULL || bn_exp == NULL || bn_modulus == NULL ||
30 	    bn_result == NULL)
31 		goto error;
32 
33 	if (bignum_set_unsigned_bin(bn_base, base, base_len) < 0 ||
34 	    bignum_set_unsigned_bin(bn_exp, power, power_len) < 0 ||
35 	    bignum_set_unsigned_bin(bn_modulus, modulus, modulus_len) < 0)
36 		goto error;
37 
38 	if (bignum_exptmod(bn_base, bn_exp, bn_modulus, bn_result) < 0)
39 		goto error;
40 
41 	ret = bignum_get_unsigned_bin(bn_result, result, result_len);
42 
43 error:
44 	bignum_deinit(bn_base);
45 	bignum_deinit(bn_exp);
46 	bignum_deinit(bn_modulus);
47 	bignum_deinit(bn_result);
48 	return ret;
49 }
50