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 FuzzerInitialize(int *argc, char ***argv) {
24 int FuzzerTestOneInput(const uint8_t *buf, size_t len) {
32 size_t l1 = 0, l2 = 0, l3 = 0;
33 int s1 = 0, s2 = 0, s3 = 0;
43 /* Divide the input into three parts, using the values of the first two
44 * bytes to choose lengths, which generate b1, b2 and b3. Use three bits
45 * of the third byte to choose signs for the three numbers.
49 l1 = (buf[0] * len) / 255;
51 l2 = (buf[0] * (len - l1)) / 255;
60 OPENSSL_assert(BN_bin2bn(buf, l1, b1) == b1);
61 BN_set_negative(b1, s1);
62 OPENSSL_assert(BN_bin2bn(buf + l1, l2, b2) == b2);
63 BN_set_negative(b2, s2);
64 OPENSSL_assert(BN_bin2bn(buf + l1 + l2, l3, b3) == b3);
65 BN_set_negative(b3, s3);
67 /* mod 0 is undefined */
73 OPENSSL_assert(BN_mod_exp(b4, b1, b2, b3, ctx));
74 OPENSSL_assert(BN_mod_exp_simple(b5, b1, b2, b3, ctx));
76 success = BN_cmp(b4, b5) == 0;
78 BN_print_fp(stdout, b1);
80 BN_print_fp(stdout, b2);
82 BN_print_fp(stdout, b3);
84 BN_print_fp(stdout, b4);
86 BN_print_fp(stdout, b5);
91 OPENSSL_assert(success);