1 /*

     2  * Copyright (c) 1997, 2007, Oracle and/or its affiliates. All rights reserved.

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

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Oracle designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Oracle in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

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

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    22  * or visit www.oracle.com if you need additional information or have any

    23  * questions.

    24  */

    25 

    26 package com.sun.crypto.provider;

    27 

    28 import javax.crypto.ShortBufferException;

    29 

    30 /**

    31  * Padding interface.

    32  *

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

    34  * the one described in PKCS#5.

    35  *

    36  * @author Jan Luehe

    37  * @author Gigi Ankeny

    38  *

    39  *

    40  * @see PKCS5Padding

    41  */

    42 

    43 interface Padding {

    44 

    45     /**

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

    47      * The value of the padding bytes is determined

    48      * by the specific padding mechanism that implements this

    49      * interface.

    50      *

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

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

    53      *  are appended

    54      * @param len the number of padding bytes to add

    55      *

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

    57      * the padding bytes

    58      */

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

    60 

    61     /**

    62      * Returns the index where padding starts.

    63      *

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

    65      * index where the padding starts.

    66      *

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

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

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

    70      *

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

    72      * not properly padded

    73      */

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

    75 

    76     /**

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

    78      *

    79      * @param len the length of the data to pad

    80      *

    81      * @return the length of the padding

    82      */

    83     int padLength(int len);

    84 }