A Simple AES Encryption – Decryption Using Java

Several days ago, my friend asked me how to create a simple AES encryption – decryption using java. Well, here is your answer, hope it will helped you.

package com.edw.testing;

import java.security.AlgorithmParameters;
import java.security.spec.KeySpec;
import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.SecretKeySpec;
import sun.misc.BASE64Encoder;

public class TestingAES {

    public TestingAES() {
    }

    private void execute() throws Exception {
        
        String password = "mypassword";
        String salt = "salt";
        String cipherText = "Hello, World!";
        
        SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
        KeySpec spec = new PBEKeySpec(password.toCharArray(), salt.getBytes(), 65536, 256);
        SecretKey tmp = factory.generateSecret(spec);
        SecretKey secret = new SecretKeySpec(tmp.getEncoded(), "AES");

        // encrypt
        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
        cipher.init(Cipher.ENCRYPT_MODE, secret);
        AlgorithmParameters params = cipher.getParameters();
        byte[] iv = params.getParameterSpec(IvParameterSpec.class).getIV();
        byte[] ciphertext = cipher.doFinal(cipherText.getBytes("UTF-8"));
        
        System.out.println("password : "+password);
        System.out.println("salt : "+salt);
        System.out.println("cipherText : "+cipherText);
        System.out.println("iv : "+new BASE64Encoder().encode(iv));
        System.out.println("ciphertext : "+new BASE64Encoder().encode(ciphertext));
        
        // decrypt
        Cipher cipherDecrypt = Cipher.getInstance("AES/CBC/PKCS5Padding");
        cipherDecrypt.init(Cipher.DECRYPT_MODE, secret, new IvParameterSpec(iv));
        String plaintext = new String(cipherDecrypt.doFinal(ciphertext), "UTF-8");
        System.out.println("decrypted text : "+plaintext);
        
    }

    public static void main(String[] args) throws Exception {
        TestingAES testingAES = new TestingAES();
        testingAES.execute();
    }
}

And this is what is written on my netbeans console,

Oh and if you ever found this kind of error

Caused by: java.security.InvalidKeyException: Illegal key size or default parameters

it means that you need to install Java Cryptography Extension (JCE). You will find it here,


http://www.oracle.com/technetwork/java/javase/downloads/jce-6-download-429243.html

Have fun :-D

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2 Comments

travis

about 1 year ago

Hey man nice example ! can you demo how to encrypt/decrypt a file? ive been trying to implement your code in my project but its not working the best (n);

Reply

edwin

about 1 year ago

Hi Travis, you can use bouncycastle to do that.

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