package com.N0TrixPM;

import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

import javax.crypto.Cipher;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.math.BigInteger;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class Crypto {

    private static String md5(final String input) throws NoSuchAlgorithmException {
        final MessageDigest md = MessageDigest.getInstance("MD5");

        final byte[] messageDigest = md.digest(input.getBytes());
        final BigInteger number = new BigInteger(1, messageDigest);
        return String.format("%032x", number);
    }

    private Cipher initCipher(final int mode, final String initialVectorString, final String secretKey)
        throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, InvalidAlgorithmParameterException {

        final SecretKeySpec skeySpec = new SecretKeySpec(md5(secretKey).getBytes(), "AES");

        final IvParameterSpec initialVector = new IvParameterSpec(initialVectorString.getBytes());

        final Cipher cipher = Cipher.getInstance("AES/CFB8/NoPadding");

        cipher.init(mode, skeySpec, initialVector);

        return cipher;

    }


    public String encrypt(final String dataToEncrypt, final String initialVector, final String secretKey) {
        String encryptedData = null;
        try {
            // Initialize the cipher
            final Cipher cipher = initCipher(Cipher.ENCRYPT_MODE, initialVector, secretKey);
            // Encrypt the data
            final byte[] encryptedByteArray = cipher.doFinal(dataToEncrypt.getBytes());
            // Encode using Base64
            encryptedData = (new BASE64Encoder()).encode(encryptedByteArray);
        } catch (Exception e) {
            System.err.println("Problem encrypting the data");
            e.printStackTrace();
        }
        return encryptedData;
    }

    public String decrypt(final String encryptedData, final String initialVector, final String secretKey) {
        String decryptedData = null;

        try {

            // Initialize the cipher

            final Cipher cipher = initCipher(Cipher.DECRYPT_MODE, initialVector, secretKey);

            // Decode using Base64

            final byte[] encryptedByteArray = (new BASE64Decoder()).decodeBuffer(encryptedData);

            // Decrypt the data

            final byte[] decryptedByteArray = cipher.doFinal(encryptedByteArray);

            decryptedData = new String(decryptedByteArray, "UTF8");

        } catch (Exception e) {

            System.err.println("Problem decrypting the data");

            e.printStackTrace();

        }

        return decryptedData;

    }



    public static void main(final String[] args) {

        final String iv = "0123456789123456"; // This has to be 16 characters

        final String secretKey = "Replace this by your secret key";

        final Crypto crypto = new Crypto();

        final String encryptedData = crypto.encrypt("This is a test message.", iv, secretKey);

        System.out.println(encryptedData);


        final String decryptedData = crypto.decrypt(encryptedData, iv, secretKey);

        System.out.println(decryptedData);

    }

}