Java BigInteger is Prime isBigPrime(BigInteger number)

Description

is Big Prime

License

Open Source License

Declaration

public static boolean isBigPrime(BigInteger number) 

Method Source Code

//package com.java2s;
/*******************************************************************************
 * Copyright (c) 2010 liXiaopeng. All rights reserved. 
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 *
 * Contributors://from www .  j  a  v a 2  s  .c om
 *     LiXiaopeng - initial API and implementation
 *
 * Create on 2011-3-7 ????03:28:18
 *******************************************************************************/

import java.math.BigInteger;

import java.util.Random;

public class Main {

    public static boolean isBigPrime(BigInteger number) {

        BigInteger random = createRandomInteger(number, new Random());

        return testPrime(number, random);
    }

    public static boolean isBigPrime(BigInteger number, int agains) {

        BigInteger[] randoms = new BigInteger[agains];
        Random r = new Random();

        for (int index = 0; index < agains; index++) {
            randoms[index] = createRandomInteger(number, r);
        }

        for (BigInteger bi : randoms) {
            if (!testPrime(number, bi)) {
                return false;
            }
        }
        return true;
    }

    private static BigInteger createRandomInteger(BigInteger number,
            Random random) {

        BigInteger result = new BigInteger(number.bitLength(), random);
        if (result.compareTo(number) >= 0) {
            result = result.divide(BigInteger.valueOf(2));
        }

        if (result.compareTo(BigInteger.valueOf(0)) == 0) {
            result = BigInteger.valueOf(1);
        }
        return result;
    }

    private static boolean testPrime(BigInteger number, BigInteger random) {

        System.out.println(random.intValue());

        BigInteger result = random.modPow(
                number.add(BigInteger.valueOf(-1)), number);

        System.out.println(result.intValue());

        return result.intValue() == 1;
    }
}

Related

1. calculateMPrime(BigInteger n, byte[] message)
2. fnvHash(final byte[] data, final BigInteger fnvOffs, final BigInteger fnvPrime, final BigInteger mod)
3. hasSqrtModPrime(BigInteger r, BigInteger p)
4. isCoprime(BigInteger a, BigInteger b)
5. isFermatPrime(BigInteger f)
6. isPrime(BigInteger value)
7. primeProcessPart(BigInteger from)