#include <gmp.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

// Generate a random large prime number between lower and upper bounds
void GenerateLargePrime(mpz_t p, mpz_t l, mpz_t u) {
    mpz_t temp;
    mpz_init(temp);

    gmp_randstate_t state;
    gmp_randinit_default(state);
    gmp_randseed_ui(state, time(NULL));

    do {
        mpz_urandomm(temp, state, u); // Generate a random number between 0 and u
        mpz_add(temp, temp, l);       // Add l to the random number to get a number between l and u
        mpz_nextprime(p, temp);       // Find the next prime number after temp
    } while (mpz_cmp(p, u) > 0);    // Repeat until the prime number is within the range [l, u]

    mpz_clear(temp);
    gmp_randclear(state);
}

int main() {
    mpz_t l, u, p;
    mpz_init(l);
    mpz_init(u);
    mpz_init(p);

    mpz_set_str(l, "57896044618658097711785492504343953926634992332820282019728792003956564819968", 10); // Set lower bound 2^255
    mpz_set_str(u, "115792089237316195423570985008687907853269984665640564039457584007913129639935", 10); // Set upper bound 2^256-1

    GenerateLargePrime(p, l, u);

    gmp_printf("Large prime: %Zd\n", p);

    mpz_clear(l);
    mpz_clear(u);
    mpz_clear(p);

    return 0;
}