import java.math.BigInteger;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.SecureRandom;
import javax.crypto.spec.DHParameterSpec;
import javax.crypto.spec.DHPublicKeySpec;
public class MainClass {
public final static int pValue = 47;
public final static int gValue = 71;
public final static int XaValue = 9;
public final static int XbValue = 14;
public static void main(String[] args) throws Exception {
BigInteger p = new BigInteger(Integer.toString(pValue));
BigInteger g = new BigInteger(Integer.toString(gValue));
BigInteger Xa = new BigInteger(Integer.toString(XaValue));
BigInteger Xb = new BigInteger(Integer.toString(XbValue));
createKey();
int bitLength = 512; // 512 bits
SecureRandom rnd = new SecureRandom();
p = BigInteger.probablePrime(bitLength, rnd);
g = BigInteger.probablePrime(bitLength, rnd);
createSpecificKey(p, g);
}
public static void createKey() throws Exception {
KeyPairGenerator kpg = KeyPairGenerator.getInstance("DiffieHellman");
kpg.initialize(512);
KeyPair kp = kpg.generateKeyPair();
KeyFactory kfactory = KeyFactory.getInstance("DiffieHellman");
DHPublicKeySpec kspec = (DHPublicKeySpec) kfactory.getKeySpec(kp.getPublic(),
DHPublicKeySpec.class);
}
public static void createSpecificKey(BigInteger p, BigInteger g) throws Exception {
KeyPairGenerator kpg = KeyPairGenerator.getInstance("DiffieHellman");
DHParameterSpec param = new DHParameterSpec(p, g);
kpg.initialize(param);
KeyPair kp = kpg.generateKeyPair();
KeyFactory kfactory = KeyFactory.getInstance("DiffieHellman");
DHPublicKeySpec kspec = (DHPublicKeySpec) kfactory.getKeySpec(kp.getPublic(),
DHPublicKeySpec.class);
}
}