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/*
* $Id: StandardDecryption.java 3117 2008-01-31 05:53:22Z xlv $
*
* Copyright 2006 Paulo Soares
*
* The contents of this file are subject to the Mozilla Public License Version 1.1
* (the "License"); you may not use this file except in compliance with the License.
* You may obtain a copy of the License at http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the License.
*
* The Original Code is 'iText, a free JAVA-PDF library'.
*
* The Initial Developer of the Original Code is Bruno Lowagie. Portions created by
* the Initial Developer are Copyright (C) 1999, 2000, 2001, 2002 by Bruno Lowagie.
* All Rights Reserved.
* Co-Developer of the code is Paulo Soares. Portions created by the Co-Developer
* are Copyright (C) 2000, 2001, 2002 by Paulo Soares. All Rights Reserved.
*
* Contributor(s): all the names of the contributors are added in the source code
* where applicable.
*
* Alternatively, the contents of this file may be used under the terms of the
* LGPL license (the "GNU LIBRARY GENERAL PUBLIC LICENSE"), in which case the
* provisions of LGPL are applicable instead of those above. If you wish to
* allow use of your version of this file only under the terms of the LGPL
* License and not to allow others to use your version of this file under
* the MPL, indicate your decision by deleting the provisions above and
* replace them with the notice and other provisions required by the LGPL.
* If you do not delete the provisions above, a recipient may use your version
* of this file under either the MPL or the GNU LIBRARY GENERAL PUBLIC LICENSE.
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the MPL as stated above or under the terms of the GNU
* Library General Public License as published by the Free Software Foundation;
* either version 2 of the License, or any later version.
*
* This library is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU Library general Public License for more
* details.
*
* If you didn't download this code from the following link, you should check if
* you aren't using an obsolete version:
* https://github.com/LibrePDF/OpenPDF
*/
package com.lowagie.text.pdf;
import com.lowagie.text.pdf.crypto.AESCipher;
import com.lowagie.text.pdf.crypto.ARCFOUREncryption;
public class StandardDecryption {
protected ARCFOUREncryption arcfour;
protected AESCipher cipher;
private byte[] key;
private static final int AES_128 = 4;
private boolean aes;
private boolean initiated;
private byte[] iv = new byte[16];
private int ivptr;
/**
* Creates a new instance of StandardDecryption
* @param key a byte array containing the key
* @param off the begining of the key in the array
* @param len the length
* @param revision the aes revision
*/
public StandardDecryption(byte[] key, int off, int len, int revision) {
aes = revision == AES_128;
if (aes) {
this.key = new byte[len];
System.arraycopy(key, off, this.key, 0, len);
}
else {
arcfour = new ARCFOUREncryption();
arcfour.prepareARCFOURKey(key, off, len);
}
}
public byte[] update(byte[] b, int off, int len) {
if (aes) {
if (initiated)
return cipher.update(b, off, len);
else {
int left = Math.min(iv.length - ivptr, len);
System.arraycopy(b, off, iv, ivptr, left);
off += left;
len -= left;
ivptr += left;
if (ivptr == iv.length) {
cipher = new AESCipher(false, key, iv);
initiated = true;
if (len > 0)
return cipher.update(b, off, len);
}
return null;
}
}
else {
byte[] b2 = new byte[len];
arcfour.encryptARCFOUR(b, off, len, b2, 0);
return b2;
}
}
public byte[] finish() {
if (aes && cipher != null) {
return cipher.doFinal();
}
else
return null;
}
}
