using System;

using System.Linq;

using System.Collections.Generic;

using System.Security.Cryptography;

using System.Text;

public class Program

{

    private const int DEFAULT_STEP = 252;

    private const int FACTOR = 4;

    public static void Main()

    {

        string seed = "frYpfgvOiHYuENamet#vaWZRk8W$quc4";

        long timestamp = 1;

        string totp = GeneratePassword(seed, timestamp);

        Console.Write(totp);

    }

    public static string GeneratePassword(string seed, long time, int step = DEFAULT_STEP / FACTOR)

    {

        IncrementalHash sha256 = IncrementalHash.CreateHash(HashAlgorithmName.SHA256);

        int factor = step * FACTOR / 60;

​

        sha256.AppendData(Encoding.UTF8.GetBytes(seed));

        sha256.AppendData(Encoding.UTF8.GetBytes((time / factor).ToString()));

​

        return Convert.ToBase64String(sha256.GetHashAndReset());

    }

}