com.thecorpora.qbo.androidapk.AESCipher.java Source code

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Here is the source code for com.thecorpora.qbo.androidapk.AESCipher.java

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/*
* Software License Agreement (GPLv2 License)
* 
* Copyright (c) 2011 Thecorpora, S.L.
*
* 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.
*
* Author: Daniel Cuadrado Snchez <daniel.cuadrado@openqbo.com>
*/
package com.thecorpora.qbo.androidapk;

import java.io.ByteArrayOutputStream;
import java.security.SecureRandom;

import org.bouncycastle.crypto.BufferedBlockCipher;
import org.bouncycastle.crypto.PBEParametersGenerator;
import org.bouncycastle.crypto.engines.AESEngine;
import org.bouncycastle.crypto.modes.CBCBlockCipher;
import org.bouncycastle.crypto.paddings.PaddedBufferedBlockCipher;

import org.bouncycastle.crypto.generators.OpenSSLPBEParametersGenerator;
import org.bouncycastle.crypto.params.KeyParameter;
import org.bouncycastle.crypto.params.ParametersWithIV;
import android.util.Base64;

public class AESCipher {

    //From https://forums.oracle.com/forums/thread.jspa?threadID=1528523

    // configData is the data that is to be encrypted
    // key is the key from which actual encryption key is to be generated

    public String encrypt(byte configData[], String key) throws Exception {
        byte[] encryptedConfigData = null;
        AESEngine blockCipher = new AESEngine();
        blockCipher.reset();
        CBCBlockCipher cbcCipher = new CBCBlockCipher(blockCipher);
        BufferedBlockCipher bbc = new PaddedBufferedBlockCipher(cbcCipher);

        byte[] salt = new byte[8];
        SecureRandom secure = new SecureRandom();
        secure.nextBytes(salt);

        //intialising in the encryption mode with Key and IV
        bbc.init(true, getKeyParamWithIv(key, salt));
        byte[] encryptedData = new byte[bbc.getOutputSize(configData.length)];

        //process array of bytes
        int noOfBytes = bbc.processBytes(configData, 0, configData.length, encryptedData, 0);

        //process the last block in the buffer
        bbc.doFinal(encryptedData, noOfBytes);

        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        //writing encrypted data along with the salt in the format readable by open ssl api
        bos.write("Salted__".getBytes());
        bos.write(salt);
        bos.write(encryptedData);
        encryptedConfigData = bos.toByteArray();
        bos.close();

        //      return encryptedConfigData;
        return Base64.encodeToString(encryptedConfigData, Base64.DEFAULT);

    }

    private ParametersWithIV getKeyParamWithIv(String keyphrase, byte[] salt) {
        int iterationCount = 1;
        //creating generator for PBE derived keys and ivs as used by open ssl
        PBEParametersGenerator generator = new OpenSSLPBEParametersGenerator();

        //intialse the PBE generator with password, salt and iteration count
        generator.init(PBEParametersGenerator.PKCS5PasswordToBytes(keyphrase.toCharArray()), salt, iterationCount);

        //Generate a key with initialisation vector parameter derived from the password, salt and iteration count
        ParametersWithIV paramWithIv = (ParametersWithIV) generator.generateDerivedParameters(256, 128);
        KeyParameter keyParam = (KeyParameter) paramWithIv.getParameters();

        return paramWithIv;
    }

}