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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

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package java.security;

import java.security.spec.AlgorithmParameterSpec;

/**

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

 * for the {@code KeyPairGenerator} class, which is used to generate

 * pairs of public and private keys.

 *

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

 * cryptographic service provider who wishes to supply the implementation

 * of a key pair generator for a particular algorithm.

 *

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

 * (via a call to an {@code initialize} 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 KeyPairGenerator 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

 * KeyPairGenerator instead of relying on provider-specific defaults.

 *

 * @author Benjamin Renaud

 * @since 1.2

 *

 *

 * @see KeyPairGenerator

 * @see java.security.spec.AlgorithmParameterSpec

 */

public abstract class KeyPairGeneratorSpi {

    /**

     * Initializes the key pair generator for a certain keysize, using

     * the default parameter set.

     *

     * @param keysize the keysize. This is an

     * algorithm-specific metric, such as modulus length, specified in

     * number of bits.

     *

     * @param random the source of randomness for this generator.

     *

     * @exception InvalidParameterException if the {@code keysize} is not

     * supported by this KeyPairGeneratorSpi object.

     */

    public abstract void initialize(int keysize, SecureRandom random);

    /**

     * Initializes the key pair generator using the specified parameter

     * set and user-provided source of randomness.

     *

     * <p>This concrete method has been added to this previously-defined

     * abstract class. (For backwards compatibility, it cannot be abstract.)

     * It may be overridden by a provider to initialize the key pair

     * generator. Such an override

     * is expected to throw an InvalidAlgorithmParameterException if

     * a parameter is inappropriate for this key pair generator.

     * If this method is not overridden, it always throws an

     * UnsupportedOperationException.

     *

     * @param params the parameter set used to generate the keys.

     *

     * @param random the source of randomness for this generator.

     *

     * @exception InvalidAlgorithmParameterException if the given parameters

     * are inappropriate for this key pair generator.

     *

     * @since 1.2

     */

    public void initialize(AlgorithmParameterSpec params,

                           SecureRandom random)

        throws InvalidAlgorithmParameterException {

            throw new UnsupportedOperationException();

    }

    /**

     * Generates a key pair. Unless an initialization method is called

     * using a KeyPairGenerator interface, algorithm-specific defaults

     * will be used. This will generate a new key pair every time it

     * is called.

     *

     * @return the newly generated {@code KeyPair}

     */

    public abstract KeyPair generateKeyPair();

}