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, 5, 7, 11, 13, 17, 19, 23, 29,
			31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101,
			103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167,
			173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239,
			241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 313,
			317, 331, 337, 347, 349, 353, 359, 367, 373, 379, 383, 389, 397,
			401, 409, 419, 421, 431, 433, 439, 443, 449, 457, 461, 463, 467,
			479, 487, 491, 499, 503, 509, 521, 523, 541, 547, 557, 563, 569,
			571, 577, 587, 593, 599, 601, 607, 613, 617, 619, 631, 641, 643,
			647, 653, 659, 661, 673, 677, 683, 691, 701, 709, 719, 727, 733,
			739, 743, 751, 757, 761, 769, 773, 787, 797, 809, 811, 821, 823,
			827, 829, 839, 853, 857, 859, 863, 877, 881, 883, 887, 907, 911,
			919, 929, 937, 941, 947, 953, 967, 971, 977, 983, 991, 997, 1009,
			1013, 1019, 1021 };

	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);
		}
		System.out.print("Base ");
		for (int i = 0; i < numValues; i++) { 
			BigInteger a = BigInteger.valueOf(aValues[i]); 
			boolean r = testPr(n, a, s, d);
			System.out.print(aValues[i] + " \n");
			if (!r) {
				return false;
			}
		}
		return true;
	}

	public static void main(String[] args) {
		long a = new Random().nextInt(999999999);
		System.out.println(millerRabin(BigInteger.valueOf((a)),
				aValues.length));
	}
}