/* KeyFactorySpi.java --- Key Factory Service Provider Interface
   Copyright (C) 1999 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU Classpath is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Classpath; see the file COPYING.  If not, write to the
Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA.

As a special exception, if you link this library with other files to
produce an executable, this library does not by itself cause the
resulting executable to be covered by the GNU General Public License.
This exception does not however invalidate any other reasons why the
executable file might be covered by the GNU General Public License. */

package java.security;
import java.security.spec.KeySpec;
import java.security.spec.InvalidKeySpecException;

/**
   KeyFactorySpi is the Service Provider Interface (SPI) for the 
   KeyFactory class. This is the interface for providers to 
   supply to implement a key factory for an algorithm.

   Key factories are used to convert keys (opaque cryptographic 
   keys of type Key) into key specifications (transparent 
   representations of the underlying key material).

   Key factories are bi-directional. They allow a key class 
   to be converted into a key specification (key material) and
   back again.

   For example DSA public keys can be specified as 
   DSAPublicKeySpec or X509EncodedKeySpec. The key factory
   translate these key specifications. 

   @since JDK 1.2
   @author Mark Benvenuto
 */
public abstract class KeyFactorySpi
{
  /**
     Constucts a new KeyFactorySpi.
   */
  public KeyFactorySpi()
  {
  }

  /**
     Generates a public key from the provided key specification.

     @param keySpec key specification

     @return the public key

     @throws InvalidKeySpecException invalid key specification for
     this key factory to produce a public key
   */
  protected abstract PublicKey engineGeneratePublic(KeySpec keySpec)
    throws InvalidKeySpecException;


  /**
     Generates a private key from the provided key specification.

     @param keySpec key specification

     @return the private key

     @throws InvalidKeySpecException invalid key specification for
     this key factory to produce a private key
   */
  protected abstract PrivateKey engineGeneratePrivate(KeySpec keySpec)
    throws InvalidKeySpecException;

  /**
     Returns a key specification for the given key. keySpec 
     identifies the specification class to return the key 
     material in.

     @param key the key
     @param keySpec the specification class to return the 
     key material in.

     @return the key specification in an instance of the requested
     specification class

     @throws InvalidKeySpecException the requested key specification
     is inappropriate for this key or the key is 
     unrecognized.
   */
  protected abstract KeySpec engineGetKeySpec(Key key, Class keySpec)
    throws InvalidKeySpecException;


  /**
     Translates the key from an unknown or untrusted provider
     into a key for this key factory.

     @param the key from an unknown or untrusted provider

     @return the translated key

     @throws InvalidKeySpecException if the key cannot be 
     processed by this key factory
   */
  protected abstract Key engineTranslateKey(Key key)
    throws InvalidKeyException;
}