110 lines
2.5 KiB
C
110 lines
2.5 KiB
C
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/*
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* Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the Apache License 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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* https://www.openssl.org/source/license.html
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* or in the file LICENSE in the source distribution.
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*/
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/*
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* Confirm that a^b mod c agrees when calculated cleverly vs naively, for
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* random a, b and c.
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*/
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#include <stdio.h>
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#include <openssl/bn.h>
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#include <openssl/err.h>
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#include "fuzzer.h"
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int FuzzerInitialize(int *argc, char ***argv)
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{
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OPENSSL_init_crypto(OPENSSL_INIT_LOAD_CRYPTO_STRINGS, NULL);
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ERR_clear_error();
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return 1;
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}
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int FuzzerTestOneInput(const uint8_t *buf, size_t len)
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{
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int success = 0;
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size_t l1 = 0, l2 = 0, l3 = 0;
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int s1 = 0, s3 = 0;
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BN_CTX *ctx;
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BIGNUM *b1;
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BIGNUM *b2;
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BIGNUM *b3;
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BIGNUM *b4;
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BIGNUM *b5;
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b1 = BN_new();
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b2 = BN_new();
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b3 = BN_new();
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b4 = BN_new();
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b5 = BN_new();
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ctx = BN_CTX_new();
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/* Divide the input into three parts, using the values of the first two
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* bytes to choose lengths, which generate b1, b2 and b3. Use three bits
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* of the third byte to choose signs for the three numbers.
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*/
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if (len > 2) {
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len -= 3;
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l1 = (buf[0] * len) / 255;
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++buf;
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l2 = (buf[0] * (len - l1)) / 255;
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++buf;
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l3 = len - l1 - l2;
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s1 = buf[0] & 1;
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s3 = buf[0] & 4;
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++buf;
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}
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OPENSSL_assert(BN_bin2bn(buf, l1, b1) == b1);
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BN_set_negative(b1, s1);
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OPENSSL_assert(BN_bin2bn(buf + l1, l2, b2) == b2);
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OPENSSL_assert(BN_bin2bn(buf + l1 + l2, l3, b3) == b3);
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BN_set_negative(b3, s3);
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/* mod 0 is undefined */
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if (BN_is_zero(b3)) {
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success = 1;
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goto done;
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}
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OPENSSL_assert(BN_mod_exp(b4, b1, b2, b3, ctx));
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OPENSSL_assert(BN_mod_exp_simple(b5, b1, b2, b3, ctx));
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success = BN_cmp(b4, b5) == 0;
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if (!success) {
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BN_print_fp(stdout, b1);
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putchar('\n');
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BN_print_fp(stdout, b2);
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putchar('\n');
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BN_print_fp(stdout, b3);
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putchar('\n');
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BN_print_fp(stdout, b4);
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putchar('\n');
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BN_print_fp(stdout, b5);
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putchar('\n');
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}
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done:
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OPENSSL_assert(success);
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BN_free(b1);
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BN_free(b2);
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BN_free(b3);
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BN_free(b4);
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BN_free(b5);
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BN_CTX_free(ctx);
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ERR_clear_error();
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return 0;
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}
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void FuzzerCleanup(void)
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{
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}
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