If you need further help you can on CodeMentor. var result = String.Concat("ESı!BJCŝPM".Zip("DUŝJXL@HÄ¡T", (a, b) => --a + "" + ++b)); var encode = "DERVÄ°Åž KAYIMBAÅœIOÄ¢LU" .Select((x, i) => new {Group = i % 2, Ch = i % 2 == 0 ? ++x : --x}) .GroupBy(item => item.Group == 1) .Select(gr => string.Concat(gr.Select(item => item.Ch))) .ToArray(); var decode = String.Concat(encode[0].Zip(encode[1], (a, b) => --a + "" + ++b)); if (result.Equals(decode)) Console.WriteLine("That`s Me!"); ©