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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 * 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.

 *

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package javax.crypto;

import java.security.Key;

import java.security.AlgorithmParameters;

import java.security.InvalidKeyException;

import java.security.InvalidAlgorithmParameterException;

import java.security.spec.AlgorithmParameterSpec;

/**

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

 * for the <code>ExemptionMechanism</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 particular exemption mechanism.

 *

 * @author Sharon Liu

 *

 * @since 1.4

 */

public abstract class ExemptionMechanismSpi {

    /**

     * Returns the length in bytes that an output buffer would need to be in

     * order to hold the result of the next

     * {@link #engineGenExemptionBlob(byte[], int) engineGenExemptionBlob}

     * operation, given the input length <code>inputLen</code> (in bytes).

     *

     * <p>The actual output length of the next

     * {@link #engineGenExemptionBlob(byte[], int) engineGenExemptionBlob}

     * call may be smaller than the length returned by this method.

     *

     * @param inputLen the input length (in bytes)

     *

     * @return the required output buffer size (in bytes)

     */

    protected abstract int engineGetOutputSize(int inputLen);

    /**

     * Initializes this exemption mechanism with a key.

     *

     * <p>If this exemption mechanism requires any algorithm parameters

     * that cannot be derived from the given <code>key</code>, the underlying

     * exemption mechanism implementation is supposed to generate the required

     * parameters itself (using provider-specific default values); in the case

     * that algorithm parameters must be specified by the caller, an

     * <code>InvalidKeyException</code> is raised.

     *

     * @param key the key for this exemption mechanism

     *

     * @exception InvalidKeyException if the given key is inappropriate for

     * this exemption mechanism.

     * @exception ExemptionMechanismException if problem(s) encountered in the

     * process of initializing.

     */

    protected abstract void engineInit(Key key)

    throws InvalidKeyException, ExemptionMechanismException;

    /**

     * Initializes this exemption mechanism with a key and a set of algorithm

     * parameters.

     *

     * <p>If this exemption mechanism requires any algorithm parameters and

     * <code>params</code> is null, the underlying exemption mechanism

     * implementation is supposed to generate the required parameters

     * itself (using provider-specific default values); in the case that

     * algorithm parameters must be specified by the caller, an

     * <code>InvalidAlgorithmParameterException</code> is raised.

     *

     * @param key the key for this exemption mechanism

     * @param params the algorithm parameters

     *

     * @exception InvalidKeyException if the given key is inappropriate for

     * this exemption mechanism.

     * @exception InvalidAlgorithmParameterException if the given algorithm

     * parameters are inappropriate for this exemption mechanism.

     * @exception ExemptionMechanismException if problem(s) encountered in the

     * process of initializing.

     */

    protected abstract void engineInit(Key key, AlgorithmParameterSpec params)

    throws InvalidKeyException, InvalidAlgorithmParameterException,

    ExemptionMechanismException;

    /**

     * Initializes this exemption mechanism with a key and a set of algorithm

     * parameters.

     *

     * <p>If this exemption mechanism requires any algorithm parameters

     * and <code>params</code> is null, the underlying exemption mechanism

     * implementation is supposed to generate the required parameters

     * itself (using provider-specific default values); in the case that

     * algorithm parameters must be specified by the caller, an

     * <code>InvalidAlgorithmParameterException</code> is raised.

     *

     * @param key the key for this exemption mechanism

     * @param params the algorithm parameters

     *

     * @exception InvalidKeyException if the given key is inappropriate for

     * this exemption mechanism.

     * @exception InvalidAlgorithmParameterException if the given algorithm

     * parameters are inappropriate for this exemption mechanism.

     * @exception ExemptionMechanismException if problem(s) encountered in the

     * process of initializing.

     */

    protected abstract void engineInit(Key key, AlgorithmParameters params)

    throws InvalidKeyException, InvalidAlgorithmParameterException,

    ExemptionMechanismException;

    /**

     * Generates the exemption mechanism key blob.

     *

     * @return the new buffer with the result key blob.

     *

     * @exception ExemptionMechanismException if problem(s) encountered in the

     * process of generating.

     */

    protected abstract byte[] engineGenExemptionBlob()

        throws ExemptionMechanismException;

    /**

     * Generates the exemption mechanism key blob, and stores the result in

     * the <code>output</code> buffer, starting at <code>outputOffset</code>

     * inclusive.

     *

     * <p>If the <code>output</code> buffer is too small to hold the result,

     * a <code>ShortBufferException</code> is thrown. In this case, repeat this

     * call with a larger output buffer. Use

     * {@link #engineGetOutputSize(int) engineGetOutputSize} to determine

     * how big the output buffer should be.

     *

     * @param output the buffer for the result

     * @param outputOffset the offset in <code>output</code> where the result

     * is stored

     *

     * @return the number of bytes stored in <code>output</code>

     *

     * @exception ShortBufferException if the given output buffer is too small

     * to hold the result.

     * @exception ExemptionMechanismException if problem(s) encountered in the

     * process of generating.

     */

    protected abstract int engineGenExemptionBlob

    (byte[] output, int outputOffset)

        throws ShortBufferException, ExemptionMechanismException;

}