001: /*
002: * $Id: StandardDecryption.java 2730 2007-04-28 12:52:49Z blowagie $
003: *
004: * Copyright 2006 Paulo Soares
005: *
006: * The contents of this file are subject to the Mozilla Public License Version 1.1
007: * (the "License"); you may not use this file except in compliance with the License.
008: * You may obtain a copy of the License at http://www.mozilla.org/MPL/
009: *
010: * Software distributed under the License is distributed on an "AS IS" basis,
011: * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
012: * for the specific language governing rights and limitations under the License.
013: *
014: * The Original Code is 'iText, a free JAVA-PDF library'.
015: *
016: * The Initial Developer of the Original Code is Bruno Lowagie. Portions created by
017: * the Initial Developer are Copyright (C) 1999, 2000, 2001, 2002 by Bruno Lowagie.
018: * All Rights Reserved.
019: * Co-Developer of the code is Paulo Soares. Portions created by the Co-Developer
020: * are Copyright (C) 2000, 2001, 2002 by Paulo Soares. All Rights Reserved.
021: *
022: * Contributor(s): all the names of the contributors are added in the source code
023: * where applicable.
024: *
025: * Alternatively, the contents of this file may be used under the terms of the
026: * LGPL license (the "GNU LIBRARY GENERAL PUBLIC LICENSE"), in which case the
027: * provisions of LGPL are applicable instead of those above. If you wish to
028: * allow use of your version of this file only under the terms of the LGPL
029: * License and not to allow others to use your version of this file under
030: * the MPL, indicate your decision by deleting the provisions above and
031: * replace them with the notice and other provisions required by the LGPL.
032: * If you do not delete the provisions above, a recipient may use your version
033: * of this file under either the MPL or the GNU LIBRARY GENERAL PUBLIC LICENSE.
034: *
035: * This library is free software; you can redistribute it and/or modify it
036: * under the terms of the MPL as stated above or under the terms of the GNU
037: * Library General Public License as published by the Free Software Foundation;
038: * either version 2 of the License, or any later version.
039: *
040: * This library is distributed in the hope that it will be useful, but WITHOUT
041: * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
042: * FOR A PARTICULAR PURPOSE. See the GNU Library general Public License for more
043: * details.
044: *
045: * If you didn't download this code from the following link, you should check if
046: * you aren't using an obsolete version:
047: * http://www.lowagie.com/iText/
048: */
049: package com.lowagie.text.pdf;
050:
051: import com.lowagie.text.pdf.crypto.AESCipher;
052: import com.lowagie.text.pdf.crypto.ARCFOUREncryption;
053:
054: public class StandardDecryption {
055: protected ARCFOUREncryption arcfour;
056: protected AESCipher cipher;
057: private byte[] key;
058: private static final int AES_128 = 4;
059: private boolean aes;
060: private boolean initiated;
061: private byte[] iv = new byte[16];
062: private int ivptr;
063:
064: /** Creates a new instance of StandardDecryption */
065: public StandardDecryption(byte key[], int off, int len, int revision) {
066: aes = revision == AES_128;
067: if (aes) {
068: this .key = new byte[len];
069: System.arraycopy(key, off, this .key, 0, len);
070: } else {
071: arcfour = new ARCFOUREncryption();
072: arcfour.prepareARCFOURKey(key, off, len);
073: }
074: }
075:
076: public byte[] update(byte[] b, int off, int len) {
077: if (aes) {
078: if (initiated)
079: return cipher.update(b, off, len);
080: else {
081: int left = Math.min(iv.length - ivptr, len);
082: System.arraycopy(b, off, iv, ivptr, left);
083: off += left;
084: len -= left;
085: ivptr += left;
086: if (ivptr == iv.length) {
087: cipher = new AESCipher(false, key, iv);
088: initiated = true;
089: if (len > 0)
090: return cipher.update(b, off, len);
091: }
092: return null;
093: }
094: } else {
095: byte[] b2 = new byte[len];
096: arcfour.encryptARCFOUR(b, off, len, b2, 0);
097: return b2;
098: }
099: }
100:
101: public byte[] finish() {
102: if (aes) {
103: return cipher.doFinal();
104: } else
105: return null;
106: }
107: }
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