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
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23 * questions.
24 */
25
26package com.sun.crypto.provider;
27
28import 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
43interface 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}
85