import java.util.Scanner;

public class Test
{
    public static void main(String argc[])
    {
        String data;
        String key;

        Scanner in = new Scanner(System.in);

        System.out.print("Enter yout data -> ");
        data = in.nextLine();

        System.out.print("Enter your key -> ");
        key = in.nextLine();

        System.out.print("Enter action (Decrypt or Encrypt) -> ");
        switch (in.next())
        {
            case "Encrypt": {
                System.out.println("Encrypted yout data -> " + Encrypt(data, key));
                break;
            }

            case "Decrypt": {
                System.out.println("Decrypted yout data -> " + Decrypt(data, key));
                break;
            }

            default: System.out.println("Error!");
        }
    }

    private static String Encrypt(String data, String key)
    {
        byte[] result = new byte[data.length()];
        byte[] bData = data.getBytes();
        byte[] bKey = key.getBytes();

        for(int i = 0; i < data.length(); i++) {
            result[i] = (byte)(bData[i] ^ bKey[i % key.length()]);
        }

        return new String(result);
    }

    private static String Decrypt(String data, String key)
    {
        byte[] result = new byte[data.length()];
        byte[] bData = data.getBytes();
        byte[] bKey = key.getBytes();

        for(int i = 0; i < data.length(); i++) {
            result[i] = (byte)(bData[i] ^ bKey[i % key.length()]);
        }

        return new String(result);
    }
}