/* 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
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any later version.

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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

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Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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this exception to your version of the library, but you are not
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exception statement from your version. */

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;
}