/*
 *  SSHTools - Java SSH2 API
 *
 *  Copyright (C) 2002-2003 Lee David Painter and Contributors.
 *
 *  Contributions made by:
 *
 *  Brett Smith
 *  Richard Pernavas
 *  Erwin Bolwidt
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version 2
 *  of the License, or (at your option) any later version.
 *
 *  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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */
package com.sshtools.j2ssh.transport.cipher;

import com.sshtools.j2ssh.transport.AlgorithmOperationException;

import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.KeySpec;

import javax.crypto.Cipher;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESedeKeySpec;
import javax.crypto.spec.IvParameterSpec;


/**
 *
 *
 * @author $author$
 * @version $Revision: 1.19 $
 */
public class TripleDesCbc extends SshCipher {
    /**  */
    protected static String algorithmName = "3des-cbc";
    Cipher cipher;

    /**
     * Creates a new TripleDesCbc object.
     */
    public TripleDesCbc() {
    }

    /**
     *
     *
     * @return
     */
    public int getBlockSize() {
        return cipher.getBlockSize();
    }

    /**
     *
     *
     * @param mode
     * @param iv
     * @param keydata
     *
     * @throws AlgorithmOperationException
     */
    public void init(int mode, byte[] iv, byte[] keydata)
        throws AlgorithmOperationException {
        try {
            KeySpec keyspec;
            Key key;

            // Create the cipher according to its algorithm
            cipher = Cipher.getInstance("DESede/CBC/NoPadding");

            byte[] actualKey = new byte[24];
            System.arraycopy(keydata, 0, actualKey, 0, 24);
            keyspec = new DESedeKeySpec(actualKey);
            key = SecretKeyFactory.getInstance("DESede").generateSecret(keyspec);
            cipher.init(((mode == ENCRYPT_MODE) ? Cipher.ENCRYPT_MODE
                                                : Cipher.DECRYPT_MODE), key,
                new IvParameterSpec(iv, 0, cipher.getBlockSize()));
        } catch (NoSuchPaddingException nspe) {
            throw new AlgorithmOperationException("Padding not supported");
        } catch (NoSuchAlgorithmException nsae) {
            throw new AlgorithmOperationException("Algorithm not supported");
        } catch (InvalidKeyException ike) {
            throw new AlgorithmOperationException("Invalid encryption key");
        } catch (InvalidKeySpecException ispe) {
            throw new AlgorithmOperationException(
                "Invalid encryption key specification");
        } catch (InvalidAlgorithmParameterException ape) {
            throw new AlgorithmOperationException("Invalid algorithm parameter");
        }
    }

    /**
     *
     *
     * @param data
     * @param offset
     * @param len
     *
     * @return
     *
     * @throws AlgorithmOperationException
     */
    public byte[] transform(byte[] data, int offset, int len)
        throws AlgorithmOperationException {
        return cipher.update(data, offset, len);
    }
}