de.tsenger.animamea.crypto.AmAESCrypto.java Source code

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Here is the source code for de.tsenger.animamea.crypto.AmAESCrypto.java

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/**
 *  Copyright 2011, Tobias Senger
 *  
 *  This file is part of animamea.
 *
 *  Animamea 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 3 of the License, or
 *  (at your option) any later version.
 *
 *  Animamea 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 animamea.  If not, see <http://www.gnu.org/licenses/>.
 */

package de.tsenger.animamea.crypto;

import org.bouncycastle.crypto.BlockCipher;
import org.bouncycastle.crypto.Mac;
import org.bouncycastle.crypto.engines.AESFastEngine;
import org.bouncycastle.crypto.macs.CMac;
import org.bouncycastle.crypto.modes.CBCBlockCipher;
import org.bouncycastle.crypto.paddings.ISO7816d4Padding;
import org.bouncycastle.crypto.paddings.PaddedBufferedBlockCipher;
import org.bouncycastle.crypto.params.KeyParameter;
import org.bouncycastle.crypto.params.ParametersWithIV;

/**
 * @author Tobias Senger (tobias@t-senger.de)
 * 
 */

public class AmAESCrypto extends AmCryptoProvider {

    private byte[] keyBytes = null;
    private KeyParameter keyP = null;
    private byte[] IV = null;
    private byte[] sscBytes = null;

    public static int blockSize = 16;

    private void initCiphers(byte[] key, byte[] iv) {

        // get the keyBytes
        keyBytes = new byte[key.length];
        System.arraycopy(key, 0, keyBytes, 0, key.length);

        keyP = new KeyParameter(keyBytes);

        // get the IV
        IV = new byte[blockSize];
        System.arraycopy(iv, 0, IV, 0, IV.length);

        // create the ciphers
        // AES block cipher in CBC mode with ISO7816d4 padding
        encryptCipher = new PaddedBufferedBlockCipher(new CBCBlockCipher(new AESFastEngine()),
                new ISO7816d4Padding());

        decryptCipher = new PaddedBufferedBlockCipher(new CBCBlockCipher(new AESFastEngine()),
                new ISO7816d4Padding());

        // create the IV parameter
        ParametersWithIV parameterIV = new ParametersWithIV(keyP, IV);

        encryptCipher.init(true, parameterIV);
        decryptCipher.init(false, parameterIV);
    }

    /*
     * (non-Javadoc)
     * 
     * @see de.tsenger.animamea.crypto.AmCryptoProvider#init(byte[], byte[])
     */
    @Override
    public void init(byte[] keyBytes, byte[] ssc) {

        sscBytes = ssc.clone();

        byte[] iv = encryptBlock(keyBytes, sscBytes);

        initCiphers(keyBytes, iv);
    }

    /*
     * (non-Javadoc)
     * 
     * @see de.tsenger.animamea.crypto.AmCryptoProvider#getMAC(byte[])
     */
    @Override
    public byte[] getMAC(byte[] data) {

        byte[] n = new byte[sscBytes.length + data.length];
        System.arraycopy(sscBytes, 0, n, 0, sscBytes.length);
        System.arraycopy(data, 0, n, sscBytes.length, data.length);
        n = addPadding(n);

        BlockCipher cipher = new AESFastEngine();
        Mac mac = new CMac(cipher, 64);

        mac.init(keyP);
        mac.update(n, 0, n.length);
        byte[] out = new byte[mac.getMacSize()];

        mac.doFinal(out, 0);

        return out;
    }

    /*
     * (non-Javadoc)
     * 
     * @see de.tsenger.animamea.crypto.AmCryptoProvider#getMAC(byte[], byte[])
     */
    @Override
    public byte[] getMAC(byte[] key, byte[] data) {
        BlockCipher cipher = new AESFastEngine();
        Mac mac = new CMac(cipher, 64); // TODO Padding der Daten

        KeyParameter keyP = new KeyParameter(key);
        mac.init(keyP);

        mac.update(data, 0, data.length);

        byte[] out = new byte[8];

        mac.doFinal(out, 0);

        return out;
    }

    /**
     * Dekodiert einen Block mit AES
     * 
     * @param key
     *            Byte-Array enthlt den AES-Schlssel
     * @param z
     *            verschlsselter Block
     * @return entschlsselter block
     */
    @Override
    public byte[] decryptBlock(byte[] key, byte[] z) {
        byte[] s = new byte[blockSize];
        KeyParameter encKey = new KeyParameter(key);
        BlockCipher cipher = new AESFastEngine();
        cipher.init(false, encKey);
        cipher.processBlock(z, 0, s, 0);
        return s;
    }

    /**
     * Kodiert einen Block mit AES
     * 
     * @param key
     *            Byte-Array enthlt den AES-Schlssel
     * @param z
     *            verschlsselter Block
     * @return entschlsselter block
     */

    public byte[] encryptBlock(byte[] key, byte[] z) {
        byte[] s = new byte[blockSize];
        KeyParameter encKey = new KeyParameter(key);
        BlockCipher cipher = new AESFastEngine();
        cipher.init(true, encKey);
        cipher.processBlock(z, 0, s, 0);
        return s;
    }

    /*
     * (non-Javadoc)
     * 
     * @see de.tsenger.animamea.crypto.AmCryptoProvider#getBlockSize()
     */
    @Override
    public int getBlockSize() {
        return blockSize;
    }

}