/* * Copyright (c) 1997, 2004, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code 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 * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.security; import java.security.spec.KeySpec;import java.security.spec.InvalidKeySpecException; /** * This class defines the <i>Service Provider Interface</i> (<b>SPI</b>) * for the <code>KeyFactory</code> class. * All the abstract methods in this class must be implemented by each * cryptographic service provider who wishes to supply the implementation * of a key factory for a particular algorithm. * * <P> Key factories are used to convert <I>keys</I> (opaque * cryptographic keys of type <code>Key</code>) into <I>key specifications</I> * (transparent representations of the underlying key material), and vice * versa. * * <P> Key factories are bi-directional. That is, they allow you to build an * opaque key object from a given key specification (key material), or to * retrieve the underlying key material of a key object in a suitable format. * * <P> Multiple compatible key specifications may exist for the same key. * For example, a DSA public key may be specified using * <code>DSAPublicKeySpec</code> or * <code>X509EncodedKeySpec</code>. A key factory can be used to translate * between compatible key specifications. * * <P> A provider should document all the key specifications supported by its * key factory. * * @author Jan Luehe * * * @see KeyFactory * @see Key * @see PublicKey * @see PrivateKey * @see java.security.spec.KeySpec * @see java.security.spec.DSAPublicKeySpec * @see java.security.spec.X509EncodedKeySpec * * @since 1.2 */ public abstract class KeyFactorySpi {     /**     * Generates a public key object from the provided key     * specification (key material).     *     * @param keySpec the specification (key material) of the public key.     *     * @return the public key.     *     * @exception InvalidKeySpecException if the given key specification     * is inappropriate for this key factory to produce a public key.     */    protected abstract PublicKey engineGeneratePublic(KeySpec keySpec)        throws InvalidKeySpecException;     /**     * Generates a private key object from the provided key     * specification (key material).     *     * @param keySpec the specification (key material) of the private key.     *     * @return the private key.     *     * @exception InvalidKeySpecException if the given key specification     * is inappropriate for this key factory to produce a private key.     */    protected abstract PrivateKey engineGeneratePrivate(KeySpec keySpec)        throws InvalidKeySpecException;     /**     * Returns a specification (key material) of the given key     * object.     * <code>keySpec</code> identifies the specification class in which     * the key material should be returned. It could, for example, be     * <code>DSAPublicKeySpec.class</code>, to indicate that the     * key material should be returned in an instance of the     * <code>DSAPublicKeySpec</code> class.     *     * @param key the key.     *     * @param keySpec the specification class in which     * the key material should be returned.     *     * @return the underlying key specification (key material) in an instance     * of the requested specification class.      * @exception InvalidKeySpecException if the requested key specification is     * inappropriate for the given key, or the given key cannot be dealt with     * (e.g., the given key has an unrecognized format).     */    protected abstract <T extends KeySpec>        T engineGetKeySpec(Key key, Class<T> keySpec)        throws InvalidKeySpecException;     /**     * Translates a key object, whose provider may be unknown or     * potentially untrusted, into a corresponding key object of this key     * factory.     *     * @param key the key whose provider is unknown or untrusted.     *     * @return the translated key.     *     * @exception InvalidKeyException if the given key cannot be processed     * by this key factory.     */    protected abstract Key engineTranslateKey(Key key)        throws InvalidKeyException; }