AES.java

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 java.nio.charset.StandardCharsets;  
import java.security.InvalidAlgorithmParameterException;  
import java.security.InvalidKeyException;  
import java.security.NoSuchAlgorithmException;  
import java.security.spec.InvalidKeySpecException;  
import java.security.spec.KeySpec;  
import java.util.Base64;  
import javax.crypto.BadPaddingException;  
import javax.crypto.IllegalBlockSizeException;  
import javax.crypto.NoSuchPaddingException;  
public class AESExample   
{  
    /* Private variable declaration */  
    private static final String SECRET_KEY = "123456789";  
    private static final String SALTVALUE = "abcdefg";  
   
    /* Encryption Method */  
    public static String encrypt(String strToEncrypt)   
    {  
    try   
    {  
      /* Declare a byte array. */  
      byte[] iv = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};  
      IvParameterSpec ivspec = new IvParameterSpec(iv);        
      /* Create factory for secret keys. */  
      SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA256");  
      /* PBEKeySpec class implements KeySpec interface. */  
      KeySpec spec = new PBEKeySpec(SECRET_KEY.toCharArray(), SALTVALUE.getBytes(), 65536, 256);  
      SecretKey tmp = factory.generateSecret(spec);  
      SecretKeySpec secretKey = new SecretKeySpec(tmp.getEncoded(), "AES");  
      Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");  
      cipher.init(Cipher.ENCRYPT_MODE, secretKey, ivspec);  
      /* Retruns encrypted value. */  
      return Base64.getEncoder()  
.encodeToString(cipher.doFinal(strToEncrypt.getBytes(StandardCharsets.UTF_8)));  
    }   
    catch (InvalidAlgorithmParameterException | InvalidKeyException | NoSuchAlgorithmException | InvalidKeySpecException | BadPaddingException | IllegalBlockSizeException | NoSuchPaddingException e)   
    {  
      System.out.println("Error occured during encryption: " + e.toString());  
    }  
    return null;  
    }  
    
    /* Decryption Method */  
    public static String decrypt(String strToDecrypt)   
    {  
    try   
    {  
      /* Declare a byte array. */  
      byte[] iv = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};  
      IvParameterSpec ivspec = new IvParameterSpec(iv);  
      /* Create factory for secret keys. */  
      SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA256");  
      /* PBEKeySpec class implements KeySpec interface. */  
      KeySpec spec = new PBEKeySpec(SECRET_KEY.toCharArray(), SALTVALUE.getBytes(), 65536, 256);  
      SecretKey tmp = factory.generateSecret(spec);  
      SecretKeySpec secretKey = new SecretKeySpec(tmp.getEncoded(), "AES");  
      Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");  
      cipher.init(Cipher.DECRYPT_MODE, secretKey, ivspec);  
      /* Retruns decrypted value. */  
      return new String(cipher.doFinal(Base64.getDecoder().decode(strToDecrypt)));  
    }   
    catch (InvalidAlgorithmParameterException | InvalidKeyException | NoSuchAlgorithmException | InvalidKeySpecException | BadPaddingException | IllegalBlockSizeException | NoSuchPaddingException e)   
    {  
      System.out.println("Error occured during decryption: " + e.toString());  
    }  
    return null;  
    }  
    /* Driver Code */  
    public static void main(String[] args)   
    {  
        /* Message to be encrypted. */  
        String originalval = "AES Encryption";  
        /* Call the encrypt() method and store result of encryption. */  
        String encryptedval = encrypt(originalval);  
        /* Call the decrypt() method and store result of decryption. */  
        String decryptedval = decrypt(encryptedval);  
        /* Display the original message, encrypted message and decrypted message on the console. */  
        System.out.println("Original value: " + originalval);  
        System.out.println("Encrypted value: " + encryptedval);  
        System.out.println("Decrypted value: " + decryptedval);  
    }  
}