com.redsqirl.workflow.utils.FileStream.java Source code

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Here is the source code for com.redsqirl.workflow.utils.FileStream.java

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/** 
 *  Copyright  2016 Red Sqirl, Ltd. All rights reserved.
 *  Red Sqirl, Clarendon House, 34 Clarendon St., Dublin 2. Ireland
 *
 *  This file is part of Red Sqirl
 *
 *  User agrees that use of this software is governed by: 
 *  (1) the applicable user limitations and specified terms and conditions of 
 *      the license agreement which has been entered into with Red Sqirl; and 
 *  (2) the proprietary and restricted rights notices included in this software.
 *  
 *  WARNING: THE PROPRIETARY INFORMATION OF Red Sqirl IS PROTECTED BY IRISH AND 
 *  INTERNATIONAL LAW.  UNAUTHORISED REPRODUCTION, DISTRIBUTION OR ANY PORTION
 *  OF IT, MAY RESULT IN CIVIL AND/OR CRIMINAL PENALTIES.
 *  
 *  If you have received this software in error please contact Red Sqirl at 
 *  support@redsqirl.com
 */

package com.redsqirl.workflow.utils;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.util.Arrays;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.PBEParameterSpec;

import org.apache.commons.io.IOUtils;

public class FileStream {

    //Arbitrarily selected 8-byte salt sequence:
    private static final byte[] salt = { (byte) 0x53, (byte) 0x7a, (byte) 0x9f, (byte) 0xc7, (byte) 0x5b,
            (byte) 0xd7, (byte) 0x25, (byte) 0x1d };
    private static final String passphrase = "The quick brown fox jumped over the lazy brown dog";
    private static final int iterations = 2000;
    private static final int keyLength = 256;

    public static void encryptFile(File in, File out) throws Exception {
        //Write the encrypted data to a new file:
        FileOutputStream outStream = new FileOutputStream(out);
        outStream.write(encryptFile(in));
        outStream.close();
    }

    public static void decryptFile(File in, File out) throws Exception {
        //Write the encrypted data to a new file:
        FileOutputStream outStream = new FileOutputStream(out);
        outStream.write(decryptFile(in));
        outStream.close();
    }

    public static byte[] encryptFile(File in) throws Exception {
        int blockSize = 8;
        //Figure out how many bytes are padded
        int paddedCount = blockSize - ((int) in.length() % blockSize);

        //Figure out full size including padding
        int padded = (int) in.length() + paddedCount;

        byte[] decData = new byte[padded];
        FileInputStream inStream = new FileInputStream(in);
        inStream.read(decData);
        inStream.close();

        //Write out padding bytes as per PKCS5 algorithm
        for (int i = (int) in.length(); i < padded; ++i) {
            decData[i] = (byte) paddedCount;
        }

        return encrypt(decData);
    }

    public static byte[] decryptFile(File in) throws Exception {
        //Decrypt the file data:
        byte[] encData;

        //Read in the file:
        FileInputStream inStream = new FileInputStream(in);
        encData = new byte[(int) in.length()];
        inStream.read(encData);
        inStream.close();

        byte[] decData = decrypt(encData);

        //Figure out how much padding to remove
        int padCount = (int) decData[decData.length - 1];

        //Naive check, will fail if plaintext file actually contained
        //this at the end
        //For robust check, check that padCount bytes at the end have same value
        if (padCount >= 1 && padCount <= 8) {
            decData = Arrays.copyOfRange(decData, 0, decData.length - padCount);
        }

        //Write the decrypted data to a new file:
        return decData;
    }

    private static byte[] encrypt(byte[] plaintext) throws Exception {
        SecretKey key = generateKey();
        PBEParameterSpec pbeParamSpec = new PBEParameterSpec(salt, 42);
        Cipher cipher = Cipher.getInstance("PBEWithMD5AndDES");
        cipher.init(Cipher.ENCRYPT_MODE, key, pbeParamSpec);
        return cipher.doFinal(plaintext);
    }

    private static byte[] decrypt(byte[] ciphertext) throws Exception {
        SecretKey key = generateKey();
        PBEParameterSpec pbeParamSpec = new PBEParameterSpec(salt, 42);
        Cipher cipher = Cipher.getInstance("PBEWithMD5AndDES");
        cipher.init(Cipher.DECRYPT_MODE, key, pbeParamSpec);
        return cipher.doFinal(ciphertext);
    }

    private static SecretKey generateKey() throws Exception {
        PBEKeySpec keySpec = new PBEKeySpec(passphrase.toCharArray(), salt, iterations, keyLength);
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("PBEWithMD5AndDES");
        return keyFactory.generateSecret(keySpec);
    }

}