/**
* calculate our initial message.
*/
public BigInteger calculateMessage()
{
DHKeyPairGenerator dhGen = new DHKeyPairGenerator();
dhGen.init(new DHKeyGenerationParameters(random, dhParams));
AsymmetricCipherKeyPair dhPair = dhGen.generateKeyPair();
this.privateValue = ((DHPrivateKeyParameters)dhPair.getPrivate()).getX();
return ((DHPublicKeyParameters)dhPair.getPublic()).getY();
}