MillerRabin.java

import java.math.BigInteger;
import java.util.Random;



public class MillerRabin {

	public static final BigInteger ZERO = BigInteger.ZERO;
	public static final BigInteger ONE = BigInteger.ONE;
	public static final BigInteger TWO = BigInteger.valueOf(2);
	public static final int[] aValues = { 2, 3 };

	public static boolean testPr(BigInteger n, BigInteger a, int s, BigInteger d) {
		for (int i = 0; i < s; i++) {
			BigInteger exp = TWO.pow(i);
			exp = exp.multiply(d);
			BigInteger res = a.modPow(exp, n);
			if (res.equals(n.subtract(ONE)) || res.equals(ONE)) {
				return true;
			}
		}
		return false;
	}

	public static boolean millerRabin(BigInteger n, int numValues) {
		BigInteger d = n.subtract(ONE); 
		int s = 0;
		while (d.mod(TWO).equals(ZERO)) {
			s++;
			d = d.divide(TWO);
		}
		for (int i = 0; i < numValues; i++) { 
			BigInteger a = BigInteger.valueOf(aValues[i]); 
			boolean r = testPr(n, a, s, d);
			if (!r) {
				return false;
			}
		}
		return true;
	}

	public static void main(String[] args) {
		BigInteger p = new BigInteger(1024, new Random());
		
		while (millerRabin(p, aValues.length) == false) {
			p = p.add(TWO);
			
		}
		System.out.println(p);
	}
}