SENG2250_Assignment3/Q2RSA.java

import java.math.BigInteger;
import java.security.SecureRandom;

public class Q2RSA {
    
    private static SecureRandom randomNum = new SecureRandom();
    private BigInteger e;
    private BigInteger p;
    private BigInteger q;
    private BigInteger n;
    private BigInteger m;
    private BigInteger d;

    Q2RSA()
    {
        generateRSA();
    }

    private void generateRSA()
    {
        //Public Key:
        e = new BigInteger("65537");
        //Generate p
        
        p = BigInteger.probablePrime(1024, randomNum);

        //Generate q
        q = BigInteger.probablePrime(1024, randomNum);

        //Generate n
        n = p.multiply(q);

        //Generate phi n
        m = ((p.subtract(BigInteger.valueOf(1))).multiply((q.subtract(BigInteger.valueOf(1)))));

        //Generate d (private key)
        d = e.modInverse(m);
    }    



    /**
     * Returns an array that represents a public key
     * 0 - n
     * 1 - e
     * @return
     */
    public BigInteger[] getPublicKey()
    {
        BigInteger[] publicKey = new BigInteger[2];
        publicKey[0] = n;
        publicKey[1] = e;

        return publicKey;
    }

    /**
     * @return the private key
     */
    public BigInteger getPrivateKey()
    {
        return d;
    }    
}