1 /* ISO10126.java -- An implementation of the ISO 10126-2 padding scheme
2 Copyright (C) 2006 Free Software Foundation, Inc.
4 This file is a part of GNU Classpath.
6 GNU Classpath is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2 of the License, or (at
9 your option) any later version.
11 GNU Classpath is distributed in the hope that it will be useful, but
12 WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU Classpath; if not, write to the Free Software
18 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
21 Linking this library statically or dynamically with other modules is
22 making a combined work based on this library. Thus, the terms and
23 conditions of the GNU General Public License cover the whole
26 As a special exception, the copyright holders of this library give you
27 permission to link this library with independent modules to produce an
28 executable, regardless of the license terms of these independent
29 modules, and to copy and distribute the resulting executable under
30 terms of your choice, provided that you also meet, for each linked
31 independent module, the terms and conditions of the license of that
32 module. An independent module is a module which is not derived from
33 or based on this library. If you modify this library, you may extend
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35 obligated to do so. If you do not wish to do so, delete this
36 exception statement from your version. */
39 package gnu.javax.crypto.pad;
41 import gnu.java.security.Registry;
42 import gnu.java.security.util.PRNG;
45 * The implementation of the ISO 10126-2 padding algorithm.
47 * The last byte of the padding block is the number of padding bytes, all other
48 * padding bytes are random.
52 * <li><a href="http://www.w3.org/TR/xmlenc-core/">XML Encryption Syntax and
53 * Processing</a> Section "5.2 Block Encryption Algorithms"; "Padding".</li>
56 public final class ISO10126
59 /** Used to generate random numbers for padding bytes. */
64 super(Registry.ISO10126_PAD);
65 prng = PRNG.getInstance();
73 public byte[] pad(byte[] in, int offset, int length)
75 int padLength = blockSize - (length % blockSize);
76 final byte[] pad = new byte[padLength];
78 // generate random numbers for the padding bytes except for the last byte
79 prng.nextBytes(pad, 0, padLength - 1);
80 // the last byte contains the number of padding bytes
81 pad[padLength - 1] = (byte) padLength;
86 public int unpad(byte[] in, int offset, int length)
87 throws WrongPaddingException
89 // the last byte contains the number of padding bytes
90 int padLength = in[offset + length - 1] & 0xFF;
91 if (padLength > length)
92 throw new WrongPaddingException();
98 * The default self-test in the super-class would take too long to finish
99 * with this type of padder --due to the large amount of random data needed.
100 * We override the default test and replace it with a simple one for a 16-byte
101 * block-size (default AES block-size). The Mauve test TestOfISO10126 will
102 * exercise all block-sizes that the default self-test uses for the other
105 public boolean selfTest()
107 return test1BlockSize(16, new byte[1024]);