using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine(HashString("1234","SGVsbG8gV29ybGQ="));

    }

    public static string HashString(string StringToHash, string HachKey)

    {

        System.Text.UTF8Encoding myEncoder = new System.Text.UTF8Encoding();

        byte[] Key = myEncoder.GetBytes(HachKey);

        byte[] Text = myEncoder.GetBytes(StringToHash);

        System.Security.Cryptography.HMACSHA1 myHMACSHA1 = new System.Security.Cryptography.HMACSHA1(Key);

        byte[] HashCode = myHMACSHA1.ComputeHash(Text);

        string hash =  BitConverter.ToString(HashCode).Replace("-", "");

        return hash.ToLower();

    }

}