How do I decrypt an object with DES?

By Wayan in Core API, Cryptography 0 Comment

On the previous example How do I encrypt an object with DES? we encrypt an object. In this example we will decrypt the stored object.

package org.kodejava.crypto;

import java.io.*;

import javax.crypto.SecretKey;
import javax.crypto.Cipher;
import javax.crypto.SealedObject;

public class ObjectDecrypt {
    public static void main(String[] args) throws Exception {
        // Read the previously stored SecretKey.
        SecretKey key = (SecretKey) readFromFile("secretkey.dat");

        // Read the SealedObject
        SealedObject sealedObject = (SealedObject) readFromFile("sealed.dat");

        // Preparing Cipher object from decryption.
        if (sealedObject != null) {
            String algorithmName = sealedObject.getAlgorithm();

            Cipher cipher = Cipher.getInstance(algorithmName);
            cipher.init(Cipher.DECRYPT_MODE, key);

            String text = (String) sealedObject.getObject(cipher);
            System.out.println("Text = " + text);
        }
    }

    // Method for reading object stored in a file.
    private static Object readFromFile(String filename) {
        try (FileInputStream fis = new FileInputStream(filename);
             ObjectInputStream ois = new ObjectInputStream(fis)) {

            return ois.readObject();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }
}

How do I encrypt an object with DES?

By Wayan in Core API, Cryptography 0 Comment

This example demonstrate encrypting an object using DES algorithm. After the object was encrypted we store it in a file which will be decrypted in the next example here How do I decrypt an object with DES.

package org.kodejava.crypto;

import java.io.*;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SealedObject;
import javax.crypto.SecretKey;

public class ObjectEncrypt {
    public static void main(String[] args) throws Exception {
        // Generating a temporary key and store it in a file.
        SecretKey key = KeyGenerator.getInstance("DES").generateKey();
        writeToFile("secretkey.dat", key);

        // Preparing Cipher object for encryption.
        Cipher cipher = Cipher.getInstance("DES");
        cipher.init(Cipher.ENCRYPT_MODE, key);

        // Here we seal (encrypt) a simple string message (a string object).
        SealedObject sealedObject = new SealedObject("THIS IS A SECRET MESSAGE!", cipher);

        // Write the object out as a binary file.
        writeToFile("sealed.dat", sealedObject);
    }

    // Store object in a file for future use.
    private static void writeToFile(String filename, Object object) throws Exception {
        try (FileOutputStream fos = new FileOutputStream(filename);
             ObjectOutputStream oos = new ObjectOutputStream(fos)) {

            oos.writeObject(object);
        }
    }
}