001/* 002 * $Id: StandardDecryption.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; 045 046import com.itextpdf.text.pdf.crypto.AESCipher; 047import com.itextpdf.text.pdf.crypto.ARCFOUREncryption; 048 049public class StandardDecryption { 050 protected ARCFOUREncryption arcfour; 051 protected AESCipher cipher; 052 private byte[] key; 053 private static final int AES_128 = 4; 054 private static final int AES_256 = 5; 055 private boolean aes; 056 private boolean initiated; 057 private byte[] iv = new byte[16]; 058 private int ivptr; 059 060 /** Creates a new instance of StandardDecryption */ 061 public StandardDecryption(byte key[], int off, int len, int revision) { 062 aes = (revision == AES_128 || revision == AES_256); 063 if (aes) { 064 this.key = new byte[len]; 065 System.arraycopy(key, off, this.key, 0, len); 066 } 067 else { 068 arcfour = new ARCFOUREncryption(); 069 arcfour.prepareARCFOURKey(key, off, len); 070 } 071 } 072 073 public byte[] update(byte[] b, int off, int len) { 074 if (aes) { 075 if (initiated) 076 return cipher.update(b, off, len); 077 else { 078 int left = Math.min(iv.length - ivptr, len); 079 System.arraycopy(b, off, iv, ivptr, left); 080 off += left; 081 len -= left; 082 ivptr += left; 083 if (ivptr == iv.length) { 084 cipher = new AESCipher(false, key, iv); 085 initiated = true; 086 if (len > 0) 087 return cipher.update(b, off, len); 088 } 089 return null; 090 } 091 } 092 else { 093 byte[] b2 = new byte[len]; 094 arcfour.encryptARCFOUR(b, off, len, b2, 0); 095 return b2; 096 } 097 } 098 099 public byte[] finish() { 100 if (aes) { 101 return cipher.doFinal(); 102 } 103 else 104 return null; 105 } 106}