import java.nio.file.Files;
import java.nio.file.Paths;
import java.security.Key;

import javax.crypto.*;
import javax.crypto.spec.SecretKeySpec;

import java.util.*;

public class Encryptor {

public static void main(String[] args) throws Exception {
    String FileName = "encryptedtext.txt";
    String FileName2 = "decryptedtext.txt";

    Scanner input = new Scanner(System.in);

   System.out.println("Enter your 16 character key here:");
   String EncryptionKey = input.next();



    KeyGenerator KeyGen = KeyGenerator.getInstance("AES");
    KeyGen.init(128);


    Cipher AesCipher = Cipher.getInstance("AES/CFB/NoPadding");
    System.out.println("Enter text to encrypt or decrypt:");
    String Text = input.next();

    System.out.println("Do you want to encrypt or decrypt (e/d)");
    String answer = input.next();
    if (answer.equalsIgnoreCase("e")){

        byte[] byteKey = (EncryptionKey.getBytes());
        byte[] byteText = (Text).getBytes();
        SecretKeySpec secretKeySpec = new SecretKeySpec(byteKey, "AES");
        AesCipher.init(Cipher.ENCRYPT_MODE, secretKeySpec );
        byte[] byteCipherText = AesCipher.doFinal(byteText);
        Files.write(Paths.get(FileName), byteCipherText);
        System.out.println(byteCipherText);


          }
    else if (answer.equalsIgnoreCase("d")){

        byte[] byteKey = (EncryptionKey.getBytes());
        byte[] byteText = (Text).getBytes();
        byte[] cipherText = Files.readAllBytes(Paths.get(FileName));

        SecretKeySpec secretKeySpec = new SecretKeySpec(byteKey, "AES");
        AesCipher.init(Cipher.DECRYPT_MODE, secretKeySpec); // ERROR LINE
        byte[] bytePlainText = AesCipher.doFinal(cipherText);
        Files.write(Paths.get(FileName2), bytePlainText);
        System.out.println(bytePlainText);
    }
}

}