using System;

using System.Security.Cryptography;

public class Program

{

    public static void Main()

    {

        var currentDate = DateTime.UtcNow.ToString("ddMMyy");

        var sercetKey = "ZFRCDfXED8rs-" + currentDate;

        var input = "/webappscustomercontact/customercontactdatapagetype?recfrom=0702190001&form=complaint";        

        var encoding = new System.Text.UTF8Encoding();

        var keyBytes = encoding.GetBytes(sercetKey);

        var messageBytes = encoding.GetBytes(input);

        using (var hmacsha1 = new HMACSHA1(keyBytes))

        {       

            var hashMessage = hmacsha1.ComputeHash(messageBytes);

            var hash = Convert.ToBase64String(hashMessage);

            Console.WriteLine("Hash: " + hash);

            Console.WriteLine("API Endpoint: " + input + "&hash=" + hash);

        }

    }

}