This interface represents a Diffie-Hellman private key. Note that it extends two interfaces: DHKey and java.security.PrivateKey. getX( ) returns the private-key value. If you are working with a PrivateKey you know is a Diffie-Hellman key, you can cast your PrivateKey to a DHPrivateKey.

Figure 17-12. javax.crypto.interfaces.DHPrivateKey

public interface DHPrivateKey extends DHKeyjava.security.PrivateKey {
// Public Constants
5.0  public static final long serialVersionUID;                      =2211791113380396553
// Public Instance Methods
     java.math.BigInteger getX( );  
}