using System;

using System.Text;

​

public class Program

{

    public class XOREncryption

    {

        public static string Base64Encode(string plainText)

        {

            return Convert.ToBase64String(Encoding.UTF8.GetBytes(plainText));

        }

​

        public static string Base64Decode(string base64EncodedData)

        {

            byte[] bytes = Convert.FromBase64String(base64EncodedData);

            return Encoding.UTF8.GetString(bytes);

        }

​

        public static string encryptDecrypt(string inputString)

        {

            char c = 'A';

            string text = "";

            int length = inputString.Length;

            for (int i = 0; i < length; i++)

            {

                text += char.ToString((char)(inputString[i] ^ c));

            }

​

            return text;

        }

    }

​

    public static void Main()

    {

        string inputString = XOREncryption.Base64Decode("AAICBBIOCQASCAUOAg4PAgQFCAUO");

        Console.WriteLine(XOREncryption.encryptDecrypt(inputString));

    }

}