/*
 *
 * This file is part of the iText (R) project.
    Copyright (c) 1998-2017 iText Group NV
 * 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
 * ITEXT GROUP. ITEXT GROUP 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.crypto;

import org.bouncycastle.crypto.BlockCipher;
import org.bouncycastle.crypto.engines.AESFastEngine;
import org.bouncycastle.crypto.modes.CBCBlockCipher;
import org.bouncycastle.crypto.paddings.PaddedBufferedBlockCipher;
import org.bouncycastle.crypto.params.KeyParameter;
import org.bouncycastle.crypto.params.ParametersWithIV;

/**
 * Creates an AES Cipher with CBC and padding PKCS5/7.
 * @author Paulo Soares
 */
public class AESCipher {
    private PaddedBufferedBlockCipher bp;
    
    /** Creates a new instance of AESCipher */
    public AESCipher(boolean forEncryption, byte[] key, byte[] iv) {
        BlockCipher aes = new AESFastEngine();
        BlockCipher cbc = new CBCBlockCipher(aes);
        bp = new PaddedBufferedBlockCipher(cbc);
        KeyParameter kp = new KeyParameter(key);
        ParametersWithIV piv = new ParametersWithIV(kp, iv);
        bp.init(forEncryption, piv);
    }
    
    public byte[] update(byte[] inp, int inpOff, int inpLen) {
        int neededLen = bp.getUpdateOutputSize(inpLen);
        byte[] outp = null;
        if (neededLen > 0)
            outp = new byte[neededLen];
        else
            neededLen = 0;
        bp.processBytes(inp, inpOff, inpLen, outp, 0);
        return outp;
    }
    
    public byte[] doFinal() {
        int neededLen = bp.getOutputSize(0);
        byte[] outp = new byte[neededLen];
        int n = 0;
        try {
            n = bp.doFinal(outp, 0);
        } catch (Exception ex) {
            return outp;
        }
        if (n != outp.length) {
            byte[] outp2 = new byte[n];
            System.arraycopy(outp, 0, outp2, 0, n);
            return outp2;
        }
        else
            return outp;
    }
    
}