using System;

using System.Text;

using System.Security.Cryptography;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

        string uid = "58";

        string key = "c277b45fa126b8174d07ae7048bf5925";

        string message = "210773 la ma xac thuc Tozaco cua ban.";

        string phone = "84383101855";

        string phoneEdit = FormatPhonenumberStartWith84(phone);

        string mac = uid+phoneEdit+message+key;

        Console.WriteLine(sha256(mac));

        Console.WriteLine("\n");

        Console.WriteLine(FormatPhonenumberStartWith84(phone));

    }

    public static string FormatPhonenumberStartWith84(string PhoneNumber)

        {

           if (PhoneNumber.StartsWith("84"))

            {

                PhoneNumber = Regex.Replace(PhoneNumber, "^84", "0");

               return PhoneNumber;

            }

        return PhoneNumber;

        }

    private static string sha256(string randomString)

        {

            var crypt = new SHA256Managed();

            var hash = new System.Text.StringBuilder();

            byte[] crypto = crypt.ComputeHash(Encoding.UTF8.GetBytes(randomString));

            foreach (byte theByte in crypto)

            {

                hash.Append(theByte.ToString("x2"));

            }

            return hash.ToString();

        }

}