import java.util.concurrent.*;
import java.math.BigInteger;
import java.util.Random;
import java.security.SecureRandom;

/** This is a Callable implementation for computing big primes. */
public class RandomPrimeSearch implements Callable<BigInteger> {
    static Random prng = new SecureRandom();  // self-seeding
    int n;
    public RandomPrimeSearch(int bitsize) { n = bitsize; }
    public BigInteger call() { return BigInteger.probablePrime(n, prng); }
}