/*
 * Copyright (c) 1997, 2007, 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 javax.crypto;

import java.security.*;
import java.security.spec.*;

/**
 * This class defines the <i>Service Provider Interface</i> (<b>SPI</b>)
 * for the <code>SecretKeyFactory</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 secret-key factory for a particular algorithm.
 *
 * <P> A provider should document all the key specifications supported by its
 * secret key factory.
 * For example, the DES secret-key factory supplied by the "SunJCE" provider
 * supports <code>DESKeySpec</code> as a transparent representation of DES
 * keys, and that provider's secret-key factory for Triple DES keys supports
 * <code>DESedeKeySpec</code> as a transparent representation of Triple DES
 * keys.
 *
 * @author Jan Luehe
 *
 * @see SecretKey
 * @see javax.crypto.spec.DESKeySpec
 * @see javax.crypto.spec.DESedeKeySpec
 * @since 1.4
 */

public abstract class SecretKeyFactorySpi {

    /**
     * Generates a <code>SecretKey</code> object from the
     * provided key specification (key material).
     *
     * @param keySpec the specification (key material) of the secret key
     *
     * @return the secret key
     *
     * @exception InvalidKeySpecException if the given key specification
     * is inappropriate for this secret-key factory to produce a secret key.
     */
    protected abstract SecretKey engineGenerateSecret(KeySpec keySpec)
        throws InvalidKeySpecException;

    /**
     * Returns a specification (key material) of the given key
     * object in the requested format.
     *
     * @param key the key
     *
     * @param keySpec the requested format in which the key material shall be
     * returned
     *
     * @return the underlying key specification (key material) in the
     * requested format
     *
     * @exception InvalidKeySpecException if the requested key specification is
     * inappropriate for the given key (e.g., the algorithms associated with
     * <code>key</code> and <code>keySpec</code> do not match, or
     * <code>key</code> references a key on a cryptographic hardware device
     * whereas <code>keySpec</code> is the specification of a software-based
     * key), or the given key cannot be dealt with
     * (e.g., the given key has an algorithm or format not supported by this
     * secret-key factory).
     */
    protected abstract KeySpec engineGetKeySpec(SecretKey key, Class keySpec)
        throws InvalidKeySpecException;

    /**
     * Translates a key object, whose provider may be unknown or
     * potentially untrusted, into a corresponding key object of this
     * secret-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 secret-key factory.
     */
    protected abstract SecretKey engineTranslateKey(SecretKey key)
        throws InvalidKeyException;
}