147 lines
3.9 KiB
C
147 lines
3.9 KiB
C
/*=============================================================================
|
|
|
|
This file is part of FLINT.
|
|
|
|
FLINT is free software; you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation; either version 2 of the License, or
|
|
(at your option) any later version.
|
|
|
|
FLINT is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
GNU General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with FLINT; if not, write to the Free Software
|
|
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
|
|
|
|
=============================================================================*/
|
|
/******************************************************************************
|
|
|
|
Copyright (C) 2011 Sebastian Pancratz
|
|
|
|
******************************************************************************/
|
|
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <gmp.h>
|
|
#include "flint.h"
|
|
#include "ulong_extras.h"
|
|
|
|
int main(void)
|
|
{
|
|
int i, result;
|
|
FLINT_TEST_INIT(state);
|
|
|
|
flint_printf("sqrtmodn....");
|
|
fflush(stdout);
|
|
|
|
|
|
|
|
for (i = 0; i < 1000 * flint_test_multiplier(); i++) /* Test random squares mod n */
|
|
{
|
|
mp_limb_t a, b, n, ninv;
|
|
slong num, i;
|
|
mp_bitcnt_t bits;
|
|
mp_limb_t * sqrt;
|
|
int btest;
|
|
n_factor_t fac;
|
|
|
|
bits = n_randint(state, 18) + 2;
|
|
n = n_randtest_bits(state, bits);
|
|
if (n == 0) n = 1;
|
|
b = n_randtest(state) % n;
|
|
|
|
n_factor_init(&fac);
|
|
n_factor(&fac, n, 0);
|
|
|
|
ninv = n_preinvert_limb(n);
|
|
a = n_mulmod2_preinv(b, b, n, ninv);
|
|
|
|
num = n_sqrtmodn(&sqrt, a, &fac);
|
|
|
|
btest = 0;
|
|
for (i = 0; i < num; i++)
|
|
{
|
|
if (a != n_mulmod2_preinv(sqrt[i], sqrt[i], n, ninv))
|
|
break;
|
|
if (sqrt[i] == b)
|
|
btest = 1;
|
|
}
|
|
|
|
result = btest & (i == num);
|
|
if (!result)
|
|
{
|
|
flint_printf("FAIL:\n");
|
|
flint_printf("n = %wu\n", n);
|
|
flint_printf("a = %wu\n", a);
|
|
flint_printf("b = %wu\n", b);
|
|
flint_printf("num = %wd\n", num);
|
|
|
|
if (!btest)
|
|
flint_printf("Square root not found.\n");
|
|
if (i != num)
|
|
flint_printf("%wu not a square root of %wu mod %wu\n", sqrt[i], a, n);
|
|
|
|
abort();
|
|
}
|
|
|
|
flint_free(sqrt);
|
|
}
|
|
|
|
for (i = 0; i < 500 * flint_test_multiplier(); i++) /* test random nonsquares */
|
|
{
|
|
mp_limb_t a, b, n, ninv;
|
|
mp_bitcnt_t bits;
|
|
mp_limb_t * sqrt;
|
|
n_factor_t fac;
|
|
|
|
bits = n_randint(state, 18) + 2;
|
|
n = n_randtest_bits(state, bits);
|
|
if (n == 2) n++;
|
|
n_factor_init(&fac);
|
|
n_factor(&fac, n, 0);
|
|
|
|
ninv = n_preinvert_limb(n);
|
|
|
|
a = n_randtest(state) % n;
|
|
while (n_sqrtmodn(&sqrt, a, &fac))
|
|
{
|
|
if (n_mulmod2_preinv(sqrt[0], sqrt[0], n, ninv) != a)
|
|
{
|
|
flint_printf("FAIL:\n");
|
|
flint_printf("%wu^2 is not %wu mod %wu\n", sqrt[0], a, n);
|
|
abort();
|
|
}
|
|
|
|
flint_free(sqrt);
|
|
a = n_randtest(state) % n;
|
|
}
|
|
|
|
for (b = 0; b < n; b++)
|
|
{
|
|
if (n_mulmod2_preinv(b, b, n, ninv) == a)
|
|
break;
|
|
}
|
|
|
|
result = (b == n);
|
|
if (!result)
|
|
{
|
|
flint_printf("FAIL:\n");
|
|
flint_printf("n = %wu\n", n);
|
|
flint_printf("a = %wu\n", a);
|
|
flint_printf("b = %wu\n", b);
|
|
|
|
abort();
|
|
}
|
|
|
|
flint_free(sqrt);
|
|
}
|
|
|
|
FLINT_TEST_CLEANUP(state);
|
|
|
|
flint_printf("PASS\n");
|
|
return 0;
|
|
}
|