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/*
* Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the OpenSSL license (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "../e_os.h"
#include <openssl/bio.h>
#include <openssl/bn.h>
#include <openssl/rand.h>
#include <openssl/err.h>
#define NUM_BITS (BN_BITS2 * 4)
static const char rnd_seed[] =
"string to make the random number generator think it has entropy";
/*
* Test that r == 0 in test_exp_mod_zero(). Returns one on success,
* returns zero and prints debug output otherwise.
*/
static int a_is_zero_mod_one(const char *method, const BIGNUM *r,
const BIGNUM *a) {
if (!BN_is_zero(r)) {
fprintf(stderr, "%s failed:\n", method);
fprintf(stderr, "a ** 0 mod 1 = r (should be 0)\n");
fprintf(stderr, "a = ");
BN_print_fp(stderr, a);
fprintf(stderr, "\nr = ");
BN_print_fp(stderr, r);
fprintf(stderr, "\n");
return 0;
}
return 1;
}
/*
* test_exp_mod_zero tests that x**0 mod 1 == 0. It returns zero on success.
*/
static int test_exp_mod_zero()
{
BIGNUM *a = NULL, *p = NULL, *m = NULL;
BIGNUM *r = NULL;
BN_ULONG one_word = 1;
BN_CTX *ctx = BN_CTX_new();
int ret = 1, failed = 0;
m = BN_new();
if (!m)
goto err;
BN_one(m);
a = BN_new();
if (!a)
goto err;
BN_one(a);
p = BN_new();
if (!p)
goto err;
BN_zero(p);
r = BN_new();
if (!r)
goto err;
if (!BN_rand(a, 1024, BN_RAND_TOP_ONE, BN_RAND_BOTTOM_ANY))
goto err;
if (!BN_mod_exp(r, a, p, m, ctx))
goto err;
if (!a_is_zero_mod_one("BN_mod_exp", r, a))
failed = 1;
if (!BN_mod_exp_recp(r, a, p, m, ctx))
goto err;
if (!a_is_zero_mod_one("BN_mod_exp_recp", r, a))
failed = 1;
if (!BN_mod_exp_simple(r, a, p, m, ctx))
goto err;
if (!a_is_zero_mod_one("BN_mod_exp_simple", r, a))
failed = 1;
if (!BN_mod_exp_mont(r, a, p, m, ctx, NULL))
goto err;
if (!a_is_zero_mod_one("BN_mod_exp_mont", r, a))
failed = 1;
if (!BN_mod_exp_mont_consttime(r, a, p, m, ctx, NULL)) {
goto err;
}
if (!a_is_zero_mod_one("BN_mod_exp_mont_consttime", r, a))
failed = 1;
/*
* A different codepath exists for single word multiplication
* in non-constant-time only.
*/
if (!BN_mod_exp_mont_word(r, one_word, p, m, ctx, NULL))
goto err;
if (!BN_is_zero(r)) {
fprintf(stderr, "BN_mod_exp_mont_word failed:\n");
fprintf(stderr, "1 ** 0 mod 1 = r (should be 0)\n");
fprintf(stderr, "r = ");
BN_print_fp(stderr, r);
fprintf(stderr, "\n");
return 0;
}
ret = failed;
err:
BN_free(r);
BN_free(a);
BN_free(p);
BN_free(m);
BN_CTX_free(ctx);
return ret;
}
int main(int argc, char *argv[])
{
BN_CTX *ctx;
BIO *out = NULL;
int i, ret;
unsigned char c;
BIGNUM *r_mont, *r_mont_const, *r_recp, *r_simple, *a, *b, *m;
/*
* Seed or BN_rand may fail, and we don't even check its return
* value (which we should)
*/
RAND_seed(rnd_seed, sizeof(rnd_seed));
ctx = BN_CTX_new();
if (ctx == NULL)
EXIT(1);
r_mont = BN_new();
r_mont_const = BN_new();
r_recp = BN_new();
r_simple = BN_new();
a = BN_new();
b = BN_new();
m = BN_new();
if ((r_mont == NULL) || (r_recp == NULL) || (a == NULL) || (b == NULL))
goto err;
out = BIO_new(BIO_s_file());
if (out == NULL)
EXIT(1);
BIO_set_fp(out, stdout, BIO_NOCLOSE | BIO_FP_TEXT);
for (i = 0; i < 200; i++) {
RAND_bytes(&c, 1);
c = (c % BN_BITS) - BN_BITS2;
BN_rand(a, NUM_BITS + c, BN_RAND_TOP_ONE, BN_RAND_BOTTOM_ANY);
RAND_bytes(&c, 1);
c = (c % BN_BITS) - BN_BITS2;
BN_rand(b, NUM_BITS + c, BN_RAND_TOP_ONE, BN_RAND_BOTTOM_ANY);
RAND_bytes(&c, 1);
c = (c % BN_BITS) - BN_BITS2;
BN_rand(m, NUM_BITS + c, BN_RAND_TOP_ONE, BN_RAND_BOTTOM_ODD);
BN_mod(a, a, m, ctx);
BN_mod(b, b, m, ctx);
ret = BN_mod_exp_mont(r_mont, a, b, m, ctx, NULL);
if (ret <= 0) {
printf("BN_mod_exp_mont() problems\n");
ERR_print_errors(out);
EXIT(1);
}
ret = BN_mod_exp_recp(r_recp, a, b, m, ctx);
if (ret <= 0) {
printf("BN_mod_exp_recp() problems\n");
ERR_print_errors(out);
EXIT(1);
}
ret = BN_mod_exp_simple(r_simple, a, b, m, ctx);
if (ret <= 0) {
printf("BN_mod_exp_simple() problems\n");
ERR_print_errors(out);
EXIT(1);
}
ret = BN_mod_exp_mont_consttime(r_mont_const, a, b, m, ctx, NULL);
if (ret <= 0) {
printf("BN_mod_exp_mont_consttime() problems\n");
ERR_print_errors(out);
EXIT(1);
}
if (BN_cmp(r_simple, r_mont) == 0
&& BN_cmp(r_simple, r_recp) == 0
&& BN_cmp(r_simple, r_mont_const) == 0) {
printf(".");
fflush(stdout);
} else {
if (BN_cmp(r_simple, r_mont) != 0)
printf("\nsimple and mont results differ\n");
if (BN_cmp(r_simple, r_mont_const) != 0)
printf("\nsimple and mont const time results differ\n");
if (BN_cmp(r_simple, r_recp) != 0)
printf("\nsimple and recp results differ\n");
printf("a (%3d) = ", BN_num_bits(a));
BN_print(out, a);
printf("\nb (%3d) = ", BN_num_bits(b));
BN_print(out, b);
printf("\nm (%3d) = ", BN_num_bits(m));
BN_print(out, m);
printf("\nsimple =");
BN_print(out, r_simple);
printf("\nrecp =");
BN_print(out, r_recp);
printf("\nmont =");
BN_print(out, r_mont);
printf("\nmont_ct =");
BN_print(out, r_mont_const);
printf("\n");
EXIT(1);
}
}
BN_free(r_mont);
BN_free(r_mont_const);
BN_free(r_recp);
BN_free(r_simple);
BN_free(a);
BN_free(b);
BN_free(m);
BN_CTX_free(ctx);
if (test_exp_mod_zero() != 0)
goto err;
#ifndef OPENSSL_NO_CRYPTO_MDEBUG
if (CRYPTO_mem_leaks(out) <= 0)
goto err;
#endif
BIO_free(out);
printf("\n");
printf("done\n");
EXIT(0);
err:
ERR_print_errors(out);
EXIT(1);
}
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