static protected byte[] GetTSAResponse(String tsaURL, string tsaUserName, string tsaPassword, byte[] hash)
        {

            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(tsaURL);

            request.Method = "POST";
             
            String hash1 = ToHexString(hash); //Convert Byte[] to HexaString
            String algo = "SHA256";
            String WC = "true";

            String respuesta = "hashAlgo=" + HttpUtility.UrlEncode(algo) + "&hashValue=" + HttpUtility.UrlEncode(hash1) + "&withCert=" + HttpUtility.UrlEncode(WC);
            
            requestBytes = StrToByteArray(respuesta);

            request.ContentType = "application/x-www-form-urlencoded";
            request.ContentLength = requestBytes.Length;
            request.PreAuthenticate = true;
            
             String userPassword = tsaUserName + ":" + tsaPassword;
            userPassword = Convert.ToBase64String(Encoding.Default.GetBytes(userPassword));
            request.Headers["Authorization"] = "Basic " + userPassword;
             
            Stream requestStream = request.GetRequestStream();
            requestStream.Write(requestBytes, 0, requestBytes.Length);
            requestStream.Flush();
            requestStream.Close();
            WebResponse response = request.GetResponse();
            Stream resStream = response.GetResponseStream();
             
            MemoryStream ms = new MemoryStream();
            byte[] responseBytes;
            byte[] buffer = new byte[4096];

            using (MemoryStream memoryStream = new MemoryStream())
            {
                int count = 0;
                do
                {
                    count = resStream.Read(buffer, 0, buffer.Length);
                    memoryStream.Write(buffer, 0, count);

                } while (count != 0);
                responseBytes = memoryStream.ToArray();
            }
            response.Close();
            return responseBytes; //return timeStampToken Object
        }