01: /*
02: * $Id: IVGenerator.java 2699 2007-04-19 12:19:40Z blowagie $
03: *
04: * Copyright 2006 Paulo Soares
05: *
06: * The contents of this file are subject to the Mozilla Public License Version 1.1
07: * (the "License"); you may not use this file except in compliance with the License.
08: * You may obtain a copy of the License at http://www.mozilla.org/MPL/
09: *
10: * Software distributed under the License is distributed on an "AS IS" basis,
11: * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
12: * for the specific language governing rights and limitations under the License.
13: *
14: * The Original Code is 'iText, a free JAVA-PDF library'.
15: *
16: * The Initial Developer of the Original Code is Bruno Lowagie. Portions created by
17: * the Initial Developer are Copyright (C) 1999, 2000, 2001, 2002 by Bruno Lowagie.
18: * All Rights Reserved.
19: * Co-Developer of the code is Paulo Soares. Portions created by the Co-Developer
20: * are Copyright (C) 2000, 2001, 2002 by Paulo Soares. All Rights Reserved.
21: *
22: * Contributor(s): all the names of the contributors are added in the source code
23: * where applicable.
24: *
25: * Alternatively, the contents of this file may be used under the terms of the
26: * LGPL license (the "GNU LIBRARY GENERAL PUBLIC LICENSE"), in which case the
27: * provisions of LGPL are applicable instead of those above. If you wish to
28: * allow use of your version of this file only under the terms of the LGPL
29: * License and not to allow others to use your version of this file under
30: * the MPL, indicate your decision by deleting the provisions above and
31: * replace them with the notice and other provisions required by the LGPL.
32: * If you do not delete the provisions above, a recipient may use your version
33: * of this file under either the MPL or the GNU LIBRARY GENERAL PUBLIC LICENSE.
34: *
35: * This library is free software; you can redistribute it and/or modify it
36: * under the terms of the MPL as stated above or under the terms of the GNU
37: * Library General Public License as published by the Free Software Foundation;
38: * either version 2 of the License, or any later version.
39: *
40: * This library is distributed in the hope that it will be useful, but WITHOUT
41: * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
42: * FOR A PARTICULAR PURPOSE. See the GNU Library general Public License for more
43: * details.
44: *
45: * If you didn't download this code from the following link, you should check if
46: * you aren't using an obsolete version:
47: * http://www.lowagie.com/iText/
48: */
49: package com.lowagie.text.pdf.crypto;
50:
51: /**
52: * An initialization vector generator for a CBC block encryption. It's a random generator based on ARCFOUR.
53: * @author Paulo Soares (psoares@consiste.pt)
54: */
55: public class IVGenerator {
56:
57: private static ARCFOUREncryption arcfour;
58:
59: static {
60: arcfour = new ARCFOUREncryption();
61: long time = System.currentTimeMillis();
62: long mem = Runtime.getRuntime().freeMemory();
63: String s = time + "+" + mem;
64: arcfour.prepareARCFOURKey(s.getBytes());
65: }
66:
67: /** Creates a new instance of IVGenerator */
68: private IVGenerator() {
69: }
70:
71: /**
72: * Gets a 16 byte random initialization vector.
73: * @return a 16 byte random initialization vector
74: */
75: public static byte[] getIV() {
76: return getIV(16);
77: }
78:
79: /**
80: * Gets a random initialization vector.
81: * @param len the length of the initialization vector
82: * @return a random initialization vector
83: */
84: public static byte[] getIV(int len) {
85: byte[] b = new byte[len];
86: synchronized (arcfour) {
87: arcfour.encryptARCFOUR(b);
88: }
89: return b;
90: }
91: }
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