using System;

using System.Text;

using System.Collections.Generic;

public class Program

{

    private static string  _key = "654sdf654gsdgadsfiu345";

    public static void Main()

    {

        var innerSellKey = GetInnerSellKey();

        var outerSellKey = GetOuterSellKey();

        Console.WriteLine("original Key:"+_key);

        Console.WriteLine("innerSellKey:"+innerSellKey);

        Console.WriteLine("outerSellKey:"+outerSellKey);

    }

    public static string GetInnerSellKey()

    {

        return ConvertKey(1);

    }

    public static string GetOuterSellKey()

    {

        return ConvertKey(2);

    }

    public static string ConvertKey(int number)

    {

        byte[] values = Encoding.ASCII.GetBytes(_key);

        var newStr = new List<string>();

​

         foreach(var value in values)

         {

             var t = value+number;

             newStr.Add(((char)t).ToString());

         }

​

        return string.Join("",newStr);

    }

}