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package java.security;

import java.security.spec.AlgorithmParameterSpec;

/**

 * This class defines the <i>Service Provider Interface</i> (<b>SPI</b>)

 * for the {@code AlgorithmParameterGenerator} class, which

 * is used to generate a set of parameters to be used with a certain algorithm.

 *

 * <p> All the abstract methods in this class must be implemented by each

 * cryptographic service provider who wishes to supply the implementation

 * of a parameter generator for a particular algorithm.

 *

 * <p> In case the client does not explicitly initialize the

 * AlgorithmParameterGenerator (via a call to an {@code engineInit}

 * 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 AlgorithmParameterGenerator 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

 * AlgorithmParameterGenerator instead of relying on provider-specific defaults.

 *

 * @author Jan Luehe

 *

 *

 * @see AlgorithmParameterGenerator

 * @see AlgorithmParameters

 * @see java.security.spec.AlgorithmParameterSpec

 *

 * @since 1.2

 */

public abstract class AlgorithmParameterGeneratorSpi {

    /**

     * Constructor for subclasses to call.

     */

    public AlgorithmParameterGeneratorSpi() {}

    /**

     * Initializes this parameter generator for a certain size

     * and source of randomness.

     *

     * @param size the size (number of bits).

     * @param random the source of randomness.

     */

    protected abstract void engineInit(int size, SecureRandom random);

    /**

     * Initializes this parameter generator with a set of

     * algorithm-specific parameter generation values.

     *

     * @param genParamSpec the set of algorithm-specific parameter generation values.

     * @param random the source of randomness.

     *

     * @throws    InvalidAlgorithmParameterException if the given parameter

     * generation values are inappropriate for this parameter generator.

     */

    protected abstract void engineInit(AlgorithmParameterSpec genParamSpec,

                                       SecureRandom random)

        throws InvalidAlgorithmParameterException;

    /**

     * Generates the parameters.

     *

     * @return the new AlgorithmParameters object.

     */

    protected abstract AlgorithmParameters engineGenerateParameters();

}