This interface represents an RSA public key
and provides direct access to the underlying key values. If you are
working with a public key you know is an RSA key, you can cast the
PublicKey to an RSAPublicKey.
Figure 14-83. java.security.interfaces.RSAPublicKey

public interface RSAPublicKey extends java.security.PublicKeyRSAKey {
// Public Constants
5.0 public static final long serialVersionUID ; =-8727434096241101194
// Public Instance Methods
java.math.BigInteger getPublicExponent ( );
}