using System;

using System.IO;

using System.Text;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        byte[] payload = Encoding.ASCII.GetBytes("HelloWorld");

        foreach (var _byte in payload) {

            Console.WriteLine($"0x{_byte:X2}");

        }

        List<byte> strPayload = new List<byte>() {(byte)("HelloWorld".Length-0)};

        strPayload.AddRange(payload);

        var strPayloadArr = strPayload.ToArray();

        using (var ms = new MemoryStream(strPayloadArr)) {

            using(var br = new BinaryReader(ms)) {

                Console.WriteLine(br.ReadString()); 

            }

        }

    }

}