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( );  
}