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/*
* SPDX-License-Identifier: CC0-1.0
*
* Copyright (C) 2024 W. Kosior <koszko@koszko.org>
*/
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include "pqcrypto_poly.h"
/* Exponent for Mersenne prime, for testing. */
#define TEST_MERSENNE_EXPONENT 7 /* 89 */
static void marsenne_prime_init(fmpz_t prime, const ulong exponent) {
fmpz_init(prime);
fmpz_ui_pow_ui(prime, 2, exponent);
fmpz_sub_ui(prime, prime, 1);
}
static void init_read_poly(fmpz_poly_t poly, FILE * file) {
bool first = true;
fmpz_t coef;
fmpz_poly_init(poly);
fmpz_init(coef);
for (ulong exponent = 0;; exponent++) {
int separator_char;
if (first) {
first = false;
} else {
separator_char = getc(file);
if (separator_char == '\n')
break;
if (separator_char != ' ')
goto error;
}
if (fmpz_fread(file, coef) < 0)
goto error;
fmpz_poly_set_coeff_fmpz(poly, exponent, coef);
}
fmpz_clear(coef);
return;
error:
fprintf(stderr, "Error reading polynomial.\n");
abort();
}
int main(const int argc, const char* const* const argv) {
fmpz_t prime; /* integer for modulo operations */
mod_centered_0_ctx_t mod_ctx;
(void) argc;
(void) argv;
/*
* Marsenne primes are used just for testing. Cryptographic algorithm
* will use different ones.
*/
marsenne_prime_init(prime, TEST_MERSENNE_EXPONENT);
printf("Prime used for modulo operations: ");
fmpz_fprint(stdout, prime);
putchar('\n');
mod_c0_ctx_init(mod_ctx, prime);
{ /* Experiment 1 — modulo addition */
fmpz_t num1, num2, num_sum;
fmpz_init_set_ui(num1, 55);
fmpz_init_set_ui(num2, 31);
fmpz_init(num_sum);
fmpz_fprint(stdout, num1);
printf(" + ");
fmpz_fprint(stdout, num2);
printf(" mod [-");
fmpz_fprint(stdout, mod_ctx[0].range_max);
putchar(',');
fmpz_fprint(stdout, mod_ctx[0].range_max);
printf("] = ");
fmpz_add(num_sum, num1, num2);
mod_c0(num_sum, mod_ctx);
fmpz_fprint(stdout, num_sum);
putchar('\n');
fmpz_clear(num1);
fmpz_clear(num2);
fmpz_clear(num_sum);
} /* End of experiment 1 */
{ /* Experiment 2 */
fmpz_poly_t poly1, poly2, poly_computed;
slong divisor_degree;
poly_ring_ctx_t poly_ring_ctx;
printf("Give first polynomial for the experiment:\n");
init_read_poly(poly1, stdin);
printf("Read polynomial: ");
fmpz_poly_print_pretty(poly1, "x");
putchar('\n');
printf("Give second polynomial for the experiment:\n");
init_read_poly(poly2, stdin);
printf("Read polynomial: ");
fmpz_poly_print_pretty(poly2, "x");
putchar('\n');
fmpz_poly_init(poly_computed);
printf("Normal product of polynomials:\n");
fmpz_poly_mul(poly_computed, poly1, poly2);
fmpz_poly_print_pretty(poly_computed, "x");
putchar('\n');
printf("Normal sum of polynomials:\n");
fmpz_poly_add(poly_computed, poly1, poly2);
fmpz_poly_print_pretty(poly_computed, "x");
putchar('\n');
printf("Give the degree m of X^m+1 polynomial to be used as ");
printf("divisor in the ring:\n");
if (flint_scanf("%wd", &divisor_degree) < 1 ||
divisor_degree < 1) {
fprintf(stderr, "Bad divisor.\n");
abort();
}
poly_ring_ctx_init(poly_ring_ctx, mod_ctx, divisor_degree);
printf("Product of polynomials in the ring:\n");
poly_mul_in_ring(poly_computed, poly1, poly2, poly_ring_ctx);
fmpz_poly_print_pretty(poly_computed, "x");
putchar('\n');
printf("Sum of polynomials in the ring:\n");
poly_add_in_ring(poly_computed, poly1, poly2, poly_ring_ctx);
fmpz_poly_print_pretty(poly_computed, "x");
putchar('\n');
fmpz_poly_clear(poly1);
fmpz_poly_clear(poly2);
fmpz_poly_clear(poly_computed);
poly_ring_ctx_clear(poly_ring_ctx);
} /* End of experiment 2 */
mod_c0_ctx_clear(mod_ctx);
fmpz_clear(prime);
flint_cleanup();
return EXIT_SUCCESS;
}
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