/* Password based encryption and decryption with AES. It is taken from 
*
*https://stackoverflow.com/questions/43190139/how-to-decrypt-a-string-using-pbe-algorithm
*  
* with a few insignificant changes
*/



import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.InvalidParameterSpecException;
import java.security.spec.KeySpec;
import javax.crypto.*;
import javax.crypto.spec.*;
import java.security.Key;
import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.SecretKeySpec;
import javax.crypto.spec.PBEParameterSpec;
import javax.crypto.spec.SecretKeySpec;


public class PBE2 {
     public static void main(
        String[]    args)
        throws Exception 
    {    

SecureRandom rnd = new SecureRandom();
    byte[] iv = new byte[16];
    rnd.nextBytes(iv);
byte[] salt = { (byte)0xc7, (byte)0x73, (byte)0x21, 
                      (byte)0x8c, (byte)0x7e, (byte)0xc8, (byte)0xee, (byte)0x99 };
    String password = "password";
    byte[] plaintext = "plaintext".getBytes();

    IvParameterSpec ivParamSpec = new IvParameterSpec(iv);
    PBEParameterSpec pbeParamSpec = new PBEParameterSpec(salt, 10000, ivParamSpec);
    PBEKeySpec keySpec = new PBEKeySpec(password.toCharArray());
    try {
        SecretKeyFactory kf = SecretKeyFactory.getInstance("PBEWithHmacSHA256AndAES_128");
        SecretKey secretKey = kf.generateSecret(keySpec);

      
        System.out.println(new String(secretKey.getEncoded()));

        // Encrypt
        Cipher enc = Cipher.getInstance("PBEWithHmacSHA256AndAES_128");
        enc.init(Cipher.ENCRYPT_MODE, secretKey, pbeParamSpec);
        byte[] ciphertext = enc.doFinal(plaintext);
        System.out.println("Encrypted text: " +  Utils.toHex(ciphertext));

        // Decrypt
        Cipher dec = Cipher.getInstance("PBEWithHmacSHA256AndAES_128");
        dec.init(Cipher.DECRYPT_MODE, secretKey, pbeParamSpec);
        byte[] decrypted = dec.doFinal(ciphertext);
        String message = new String(decrypted);

        System.out.println(message);

    } catch (NoSuchAlgorithmException | InvalidKeySpecException e) {
        e.printStackTrace();
    }
}
}