Example of Advanced Encryption Standard (AES) using JAVA

Example of AES using JAVA : 

Note : For base64 related method visit this post.

import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.SecureRandom;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;



/**
 * 
 * @author : ThinkTank
 * 
 * 
 */


public class AESEncryption {
 private KeyGenerator keyGenerator;
 private SecureRandom secureRandom;
 private byte[] randomBytes = new byte[100];
 private byte[] encryptedData = new byte[20000];
 private byte[] decryptedData = new byte[20000];
 private String encryptedDataAsBase64String;
 private SecretKey secretKey;
 private SecretKeySpec secretKeySpec;
 private Cipher cipher;
 private String originalData;



 /**
  * This method will encrypt data as our desired level
  * 
  * @param data data to be encrypted
  * @param encryptionLevel level of encryption
  * @param secureRandomSeed seed value 
  * @return encrypted string
  */
 public String encrypt(byte[] data,int encryptionLevel,int secureRandomSeed) {
  try {
   keyGenerator = KeyGenerator.getInstance("AES");
   keyGenerator.init(encryptionLevel);

   secureRandom = SecureRandom.getInstance("SHA1PRNG", "SUN");
   secureRandom.setSeed(secureRandomSeed);

   secureRandom.nextBytes(randomBytes);

   secretKey = keyGenerator.generateKey();
   byte[] primaryEncodedKey = secretKey.getEncoded();

   secretKeySpec = new SecretKeySpec(primaryEncodedKey, "AES");

   cipher = Cipher.getInstance("AES");
   cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec);

   encryptedData = cipher.doFinal(data);

   encryptedDataAsBase64String = Util.byteToBase64(encryptedData);

  } catch (NoSuchProviderException e) {
   e.getStackTrace();
  } catch (NoSuchAlgorithmException e) {
   e.getStackTrace();
  } catch (NoSuchPaddingException e) {
   e.getStackTrace();
  } catch (InvalidKeyException e) {
   e.getStackTrace();
  } catch (BadPaddingException e) {
   e.getStackTrace();
  } catch (IllegalBlockSizeException e) {
   e.getStackTrace();
  }
  return encryptedDataAsBase64String;
 }

 /**
  * This method will return decrypted data
  *  
  * @return decrypted data as string 
  */
 public String decrypt(byte[] encryptedData) {
  
  try {
   cipher.init(Cipher.DECRYPT_MODE, secretKeySpec);
   decryptedData = cipher.doFinal(encryptedData);
   originalData = new String(decryptedData);
  } catch (InvalidKeyException e) {
   e.getStackTrace();
  } catch (IllegalBlockSizeException e) {
   e.getStackTrace();
  } catch (BadPaddingException e) {
   e.getStackTrace();
  }
  return originalData;
 }
}

Install Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files 6

• Step one :
  Download required files from hear. This two file are not shifted with standalone jre download. Hear you will get two file namely :
  • local_policy.jar
  • US_export_policy.jar
• Step Tow :
  Find jre installation directory in your windows/linux machine .
  And locate the path

  C:\Program Files\Java\jre6\lib\security  
  //[in case of my windows 7 machine]

  
  
• Step Three :
  Just past downloaded two files in located directory and overwrite previous two.

This will facilitate AES key generation up to 256 bits.

Example :

keyGenerator = KeyGenerator.getInstance("AES");
keyGenerator.init(256);

For enthusiastic readers further reference on Java Security