/*
* $Id: StandardDecryption.java 5075 2012-02-27 16:36:18Z blowagie $
*
* This file is part of the iText (R) project.
* Copyright (c) 1998-2012 1T3XT BVBA
* Authors: Bruno Lowagie, Paulo Soares, et al.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License version 3
* as published by the Free Software Foundation with the addition of the
* following permission added to Section 15 as permitted in Section 7(a):
* FOR ANY PART OF THE COVERED WORK IN WHICH THE COPYRIGHT IS OWNED BY 1T3XT,
* 1T3XT DISCLAIMS THE WARRANTY OF NON INFRINGEMENT OF THIRD PARTY RIGHTS.
*
* This program 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 Affero General Public License for more details.
* You should have received a copy of the GNU Affero General Public License
* along with this program; if not, see http://www.gnu.org/licenses or write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA, 02110-1301 USA, or download the license from the following URL:
* http://itextpdf.com/terms-of-use/
*
* The interactive user interfaces in modified source and object code versions
* of this program must display Appropriate Legal Notices, as required under
* Section 5 of the GNU Affero General Public License.
*
* In accordance with Section 7(b) of the GNU Affero General Public License,
* a covered work must retain the producer line in every PDF that is created
* or manipulated using iText.
*
* You can be released from the requirements of the license by purchasing
* a commercial license. Buying such a license is mandatory as soon as you
* develop commercial activities involving the iText software without
* disclosing the source code of your own applications.
* These activities include: offering paid services to customers as an ASP,
* serving PDFs on the fly in a web application, shipping iText with a closed
* source product.
*
* For more information, please contact iText Software Corp. at this
* address: sales@itextpdf.com
*/
package com.itextpdf.text.pdf;
import com.itextpdf.text.pdf.crypto.AESCipher;
import com.itextpdf.text.pdf.crypto.ARCFOUREncryption;
public class StandardDecryption {
protected ARCFOUREncryption arcfour;
protected AESCipher cipher;
private byte[] key;
private static final int AES_128 = 4;
private static final int AES_256 = 5;
private boolean aes;
private boolean initiated;
private byte[] iv = new byte[16];
private int ivptr;
/** Creates a new instance of StandardDecryption */
public StandardDecryption(byte key[], int off, int len, int revision) {
aes = (revision == AES_128 || revision == AES_256);
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) {
return cipher.doFinal();
}
else
return null;
}
}