How to integrate Digital signature in ASP.NET PDF Viewer?

   <script type="text/javascript">
        var xPos= null;
        var yPos= null;
        var jsonResult = new Object();
        document.getElementById('fileUpload').addEventListener('change', readFile, false);
       // Uploads the digital signature
        function readFile(evt) {
            var upoadedFiles = evt.target.files;
            var uploadedFile = upoadedFiles[0];
            var reader = new FileReader();
            reader.readAsDataURL(uploadedFile);
            reader.onload = function () {
         //Sends the uploaded data as base64 string, X-Coordinate, Y-Coordinate and Page Number to the sever side using the Ajax request
                var obj = $("#pdfviewer").data("ejPdfViewer");
                var uploadedFileUrl = this.result;
                jsonResult["pageNum"] = obj._currentPage;
                jsonResult["sign"] = (this.result).split(",")[1];
                jsonResult["xPos"] = xPos;
                jsonResult["yPos"] = yPos;
                jsonResult["id"] = obj._fileId;
                $.ajax({
                    url: '../api/PdfViewer/SignatureDownload',
                    method: 'POST',
                   crossDomain: true,
                    contentType: 'application/json; charset=utf-8',
                    dataType: 'json',
                    data: JSON.stringify(jsonResult),
                    traditional: true,
                    success: function (data) {
                         alert(data);
                    },
                    error: function (jqXHR, textStatus) {
                        alert("Request failed: " + textStatus);
                    }
                });
            }
        }
          $(function () {
               //Hooks the pageClick event to the PDF Viewer
               var _ejPdfViewer = $("#pdfviewer").data("ejPdfViewer");
                _ejPdfViewer.model.pageClick = "pageClicked";
            });
            function pageClicked(sender) {
                xPos = sender.XCoordinate;
                yPos = sender.YCoordinate;
                var _ejPdfViewer = $("#pdfviewer").data("ejPdfViewer");
               $('#fileUpload').click();
                }
    </script>

public object SignatureDownload(Dictionary<string, string> jsonResult)
        {
            PdfViewerHelper helper = new PdfViewerHelper();           
            object pdfData = (object)helper.GetDocumentData(jsonResult);              
            //Gets the X Coordinate, Y coordinate and Page number from the Json data            
            var x = JsonConvert.DeserializeObject<float>(jsonResult["xPos"]);
            var y = JsonConvert.DeserializeObject<float>(jsonResult["yPos"]);
            var pageNum = JsonConvert.DeserializeObject<float>(jsonResult["pageNum"]);
            byte[] byteArray = Convert.FromBase64String(jsonResult["sign"]);
            MemoryStream stream = new MemoryStream(byteArray);
            //storing the .pfx file locally.                                                        File.WriteAllBytes(HttpContext.Current.Server.MapPath("~/Data/PDFsign.pfx"), byteArray);
          //Get the document stream as base64 string            
           var propertyInfo = pdfData.GetType().GetProperty("documentStream");
            string value = propertyInfo.GetValue(pdfData, null).ToString();
            byte[] byteContents = Convert.FromBase64String(value);
            MemoryStream memoryStreams = new MemoryStream(byteContents);
            //load the document again for including the signature.
            PdfLoadedDocument pdfldoc = new PdfLoadedDocument(memoryStreams);
            PdfLoadedPage page = pdfldoc.Pages[(int)pageNum-1] as PdfLoadedPage;
            PdfSignatureField signatureField = new PdfSignatureField(page, "SignatureField");
           //Adding bounds for the signature field.
            signatureField.Bounds = new RectangleF((float)x, (float)y, 100, 100);
            signatureField.Signature = new PdfSignature();
            //Adds certificate to the signature field.
            signatureField.Signature.Certificate = new PdfCertificate(HttpContext.Current.Server.MapPath("~/Data/PDFsign.pfx"), "syncfusion");           
            signatureField.Signature.Reason = "I am author of this document";
            //Adds the field.
            pdfldoc.Form.Fields.Add(signatureField);
            //Saves the certified PDF document in Data folder.
           pdfldoc.Save(HttpContext.Current.Server.MapPath("~/Data/Output.pdf"));                        
           pdfldoc.Close(true);
            string output ="Document is saved in " + HttpContext.Current.Server.MapPath("~/Data");
            return output;                  
        }