2 * Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.
4 * Licensed under the OpenSSL licenses, (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 * https://www.openssl.org/source/license.html
8 * or in the file LICENSE in the source distribution.
12 * Confirm that a^b mod c agrees when calculated cleverly vs naively, for
17 #include <openssl/bn.h>
20 int FuzzerTestOneInput(const uint8_t *buf, size_t len) {
23 static BN_MONT_CTX *mont;
37 mont = BN_MONT_CTX_new();
39 // Divide the input into three parts, using the values of the first two
40 // bytes to choose lengths, which generate b1, b2 and b3. Use three bits
41 // of the third byte to choose signs for the three numbers.
42 size_t l1 = 0, l2 = 0, l3 = 0;
43 int s1 = 0, s2 = 0, s3 = 0;
46 l1 = (buf[0] * len) / 255;
48 l2 = (buf[0] * (len - l1)) / 255;
57 OPENSSL_assert(BN_bin2bn(buf, l1, b1) == b1);
58 BN_set_negative(b1, s1);
59 OPENSSL_assert(BN_bin2bn(buf + l1, l2, b2) == b2);
60 BN_set_negative(b2, s2);
61 OPENSSL_assert(BN_bin2bn(buf + l1 + l2, l3, b3) == b3);
62 BN_set_negative(b3, s3);
70 OPENSSL_assert(BN_mod_exp(b4, b1, b2, b3, ctx));
71 OPENSSL_assert(BN_mod_exp_simple(b5, b1, b2, b3, ctx));
73 success = BN_cmp(b4, b5) == 0;
75 BN_print_fp(stdout, b1);
77 BN_print_fp(stdout, b2);
79 BN_print_fp(stdout, b3);
81 BN_print_fp(stdout, b4);
83 BN_print_fp(stdout, b5);
88 OPENSSL_assert(success);