/* KeyFactorySpi.java --- Key Factory Service Provider Interface
   Copyright (C) 1999, 2004  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., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
conditions of the GNU General Public License cover the whole
combination.

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
modules, and to copy and distribute the resulting executable under
terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
module.  An independent module is a module which is not derived from
or based on this library.  If you modify this library, you may extend
this exception to your version of the library, but you are not
obligated to do so.  If you do not wish to do so, delete this
exception statement from your version. */


package java.security;

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

/**
 * 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 <T extends KeySpec> T engineGetKeySpec(Key key,
                                                            Class<T> keySpec)
    throws InvalidKeySpecException;


  /**
   * Translates the key from an unknown or untrusted provider
   * into a key for this key factory.
   *
   * @param key key from an unknown or untrusted provider
   *
   * @return the translated key
   *
   * @throws InvalidKeyException if the key cannot be
   * processed by this key factory
   */
  protected abstract Key engineTranslateKey(Key key)
    throws InvalidKeyException;
}