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

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 * 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).

 *

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package com.sun.crypto.provider;

import javax.crypto.ShortBufferException;

/**

 * Padding interface.

 *

 * This interface is implemented by general-purpose padding schemes, such as

 * the one described in PKCS#5.

 *

 * @author Jan Luehe

 * @author Gigi Ankeny

 *

 *

 * @see PKCS5Padding

 */

interface Padding {

    /**

     * Adds the given number of padding bytes to the data input.

     * The value of the padding bytes is determined

     * by the specific padding mechanism that implements this

     * interface.

     *

     * @param in the input buffer with the data to pad

     * @param the offset in <code>in</code> where the padding bytes

     *  are appended

     * @param len the number of padding bytes to add

     *

     * @exception ShortBufferException if <code>in</code> is too small to hold

     * the padding bytes

     */

    void padWithLen(byte[] in, int off, int len) throws ShortBufferException;

    /**

     * Returns the index where padding starts.

     *

     * <p>Given a buffer with data and their padding, this method returns the

     * index where the padding starts.

     *

     * @param in the buffer with the data and their padding

     * @param off the offset in <code>in</code> where the data starts

     * @param len the length of the data and their padding

     *

     * @return the index where the padding starts, or -1 if the input is

     * not properly padded

     */

    int unpad(byte[] in, int off, int len);

    /**

     * Determines how long the padding will be for a given input length.

     *

     * @param len the length of the data to pad

     *

     * @return the length of the padding

     */

    int padLength(int len);

}