using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication2
{
    class Program
    {
        static public byte Xor(byte a, byte b)
        {
            byte result = 0;
            bool bitA, bitB, bitXor;
            for (int i = 7; i >= 0; i--)
            {
                bitA = ((1 << i) & a) != 0;
                bitB = ((1 << i) & b) != 0;
                bitXor = (!bitA && bitB) || (bitA && !bitB);
                result |= Convert.ToByte(bitXor);
                if (i > 0)
                {
                    result = (byte)(result << 1);
                }
            }
            return result;
        }

        static void Main(string[] args)
        {
            var input = Encoding.UTF8.GetBytes("Hello world!");
            var key = Encoding.UTF8.GetBytes("i'm supa xor");
            var result = new List<byte>();

            for (int i = 0; i < input.Length; i++)
            {
                result.Add(Xor(input[i], key[i]));
                Console.WriteLine("{0} xor {1} = {2}", input[i], key[i], Xor(input[i], key[i]));
            }
            Console.WriteLine("Bytes: {0}", result.ConvertAll(b => b.ToString()).Aggregate((a, b) => a + " " + b));
            Console.WriteLine("String: {0}", Encoding.UTF8.GetString(result.ToArray()));
        }
    }
}