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/*
 * Copyright (c) 1997, 2020, 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
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package javax.crypto;

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

/**
 * This class defines the Service Provider Interface (SPI)
 * for the KeyGenerator 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 generator for a particular algorithm.
 *
 * In case the client does not explicitly initialize the KeyGenerator
 * (via a call to an {@code init} method), each provider must
 * supply (and document) a default initialization.
 * See the Keysize Restriction sections of the
 * {@extLink security_guide_jdk_providers JDK Providers}
 * document for information on the KeyGenerator defaults used by
 * JDK providers.
 * However, note that defaults may vary across different providers.
 * Additionally, the default value for a provider may change in a future
 * version. Therefore, it is recommended to explicitly initialize the
 * KeyGenerator instead of relying on provider-specific defaults.
 *
 * @author Jan Luehe
 *
 * @see SecretKey
 * @since 1.4
 */

public abstract class KeyGeneratorSpi {

    /**
     * Constructor for subclasses to call.
     */
    public KeyGeneratorSpi() {}

    /**
     * Initializes the key generator.
     *
     * @param random the source of randomness for this generator
     */
    protected abstract void engineInit(SecureRandom random);

    /**
     * Initializes the key generator with the specified parameter
     * set and a user-provided source of randomness.
     *
     * @param params the key generation parameters
     * @param random the source of randomness for this key generator
     *
     * @exception InvalidAlgorithmParameterException if params is
     * inappropriate for this key generator
     */
    protected abstract void engineInit(AlgorithmParameterSpec params,
                                       SecureRandom random)
        throws InvalidAlgorithmParameterException;

    /**
     * Initializes this key generator for a certain keysize, using the given
     * source of randomness.
     *
     * @param keysize the keysize. This is an algorithm-specific metric,
     * specified in number of bits.
     * @param random the source of randomness for this key generator
     *
     * @exception InvalidParameterException if the keysize is wrong or not
     * supported.
     */
    protected abstract void engineInit(int keysize, SecureRandom random);

    /**
     * Generates a secret key.
     *
     * @return the new key
     */
    protected abstract SecretKey engineGenerateKey();
}