using System;

using System.Text;

using System.Security.Cryptography;

public class Program

{

    public static void Main()

    {

        var otp = GetPasswordHash("N6aBQrfJEFQp37C5","OCY1OIE^6f$Q*RclrK!$KJJIZy7yIq#LoEIQVtg&LuGSFZULPHWhbAiad5awVOW0",DateTimeOffset.FromUnixTimeSeconds(1542264916).UtcDateTime, "375630");

        Console.WriteLine(otp);

    }

    private static string GetPasswordHash(string password, string secret, DateTime time, string addData) {

            var combinedPassword = string.Concat(

                secret, // Secret

                time.ToString("yyyyMMddHHmmss"), // UTC Time

                password, // User's Passport

                addData); // First parameter from payment

            var bytes = Encoding.UTF8.GetBytes(combinedPassword);

            using (var managed = new SHA512Managed()) {

                var hash = managed.ComputeHash(bytes);

                return Convert.ToBase64String(hash);

            }

        }

}