001/* 002 * $Id: IVGenerator.java 4784 2011-03-15 08:33:00Z blowagie $ 003 * 004 * This file is part of the iText (R) project. 005 * Copyright (c) 1998-2011 1T3XT BVBA 006 * Authors: Bruno Lowagie, Paulo Soares, et al. 007 * 008 * This program is free software; you can redistribute it and/or modify 009 * it under the terms of the GNU Affero General Public License version 3 010 * as published by the Free Software Foundation with the addition of the 011 * following permission added to Section 15 as permitted in Section 7(a): 012 * FOR ANY PART OF THE COVERED WORK IN WHICH THE COPYRIGHT IS OWNED BY 1T3XT, 013 * 1T3XT DISCLAIMS THE WARRANTY OF NON INFRINGEMENT OF THIRD PARTY RIGHTS. 014 * 015 * This program is distributed in the hope that it will be useful, but 016 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 017 * or FITNESS FOR A PARTICULAR PURPOSE. 018 * See the GNU Affero General Public License for more details. 019 * You should have received a copy of the GNU Affero General Public License 020 * along with this program; if not, see http://www.gnu.org/licenses or write to 021 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, 022 * Boston, MA, 02110-1301 USA, or download the license from the following URL: 023 * http://itextpdf.com/terms-of-use/ 024 * 025 * The interactive user interfaces in modified source and object code versions 026 * of this program must display Appropriate Legal Notices, as required under 027 * Section 5 of the GNU Affero General Public License. 028 * 029 * In accordance with Section 7(b) of the GNU Affero General Public License, 030 * a covered work must retain the producer line in every PDF that is created 031 * or manipulated using iText. 032 * 033 * You can be released from the requirements of the license by purchasing 034 * a commercial license. Buying such a license is mandatory as soon as you 035 * develop commercial activities involving the iText software without 036 * disclosing the source code of your own applications. 037 * These activities include: offering paid services to customers as an ASP, 038 * serving PDFs on the fly in a web application, shipping iText with a closed 039 * source product. 040 * 041 * For more information, please contact iText Software Corp. at this 042 * address: sales@itextpdf.com 043 */ 044package com.itextpdf.text.pdf.crypto; 045 046/** 047 * An initialization vector generator for a CBC block encryption. It's a random generator based on ARCFOUR. 048 * @author Paulo Soares 049 */ 050public final class IVGenerator { 051 052 private static ARCFOUREncryption arcfour; 053 054 static { 055 arcfour = new ARCFOUREncryption(); 056 long time = System.currentTimeMillis(); 057 long mem = Runtime.getRuntime().freeMemory(); 058 String s = time + "+" + mem; 059 arcfour.prepareARCFOURKey(s.getBytes()); 060 } 061 062 /** Creates a new instance of IVGenerator */ 063 private IVGenerator() { 064 } 065 066 /** 067 * Gets a 16 byte random initialization vector. 068 * @return a 16 byte random initialization vector 069 */ 070 public static byte[] getIV() { 071 return getIV(16); 072 } 073 074 /** 075 * Gets a random initialization vector. 076 * @param len the length of the initialization vector 077 * @return a random initialization vector 078 */ 079 public static byte[] getIV(int len) { 080 byte[] b = new byte[len]; 081 synchronized (arcfour) { 082 arcfour.encryptARCFOUR(b); 083 } 084 return b; 085 } 086}