Add A Digital Signature to Generated PDF Document

using System;
using System.Collections.Generic;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

using System.Drawing;

// Use EVO PDF Namespace
using EvoPdfClient;

namespace EvoHtmlToPdfDemo.HTML_to_PDF.PDF_Security
{
    public partial class Digital_Signatures : System.Web.UI.Page
    {
        protected void convertToPdfButton_Click(object sender, EventArgs e)
        {
            // Get the server IP and port
            String serverIP = textBoxServerIP.Text;
            uint serverPort = uint.Parse(textBoxServerPort.Text);

            // Create a HTML to PDF converter object
            HtmlToPdfConverter htmlToPdfConverter = null;
            if (radioButtonUseTcpService.Checked)
                htmlToPdfConverter = new HtmlToPdfConverter(serverIP, serverPort);
            else
                htmlToPdfConverter = new HtmlToPdfConverter(true, textBoxWebServiceUrl.Text);

            // Set optional service password
            if (textBoxServicePassword.Text.Length > 0)
                htmlToPdfConverter.ServicePassword = textBoxServicePassword.Text;

            // Set license key received after purchase to use the converter in licensed mode
            // Leave it not set to use the converter in demo mode
            htmlToPdfConverter.LicenseKey = "4W9+bn19bn5ue2B+bn1/YH98YHd3d3c=";

            // Set an adddional delay in seconds to wait for JavaScript or AJAX calls after page load completed
            // Set this property to 0 if you don't need to wait for such asynchcronous operations to finish
            htmlToPdfConverter.ConversionDelay = 2;

            string htmlWithDigitalSignatureMarker = htmlStringTextBox.Text;
            string baseUrl = baseUrlTextBox.Text;

            // Convert a HTML string with a marker for digital signature to a PDF document object
            Document pdfDocument = htmlToPdfConverter.ConvertHtmlToPdfDocumentObject(htmlWithDigitalSignatureMarker, baseUrl);

            // Make the HTML element with 'digital_signature_element' mapping ID a link to digital signature properties
            HtmlElementMapping digitalSignatureMapping = htmlToPdfConverter.HtmlElementsMappingOptions.HtmlElementsMappingResult.GetElementByMappingId("digital_signature_element");
            if (digitalSignatureMapping != null)
            {
                PdfPage digitalSignaturePage = pdfDocument.GetPage(digitalSignatureMapping.PdfRectangles[0].PageIndex);
                RectangleFloat digitalSignatureRectangle = digitalSignatureMapping.PdfRectangles[0].Rectangle;

                string certificateFilePath = Server.MapPath("~/DemoAppFiles/Input/Certificates/evopdf.pfx");

                // Create the digital signature
                DigitalSignatureElement signature = new DigitalSignatureElement(digitalSignatureRectangle, certificateFilePath, "evopdf", 0);
                signature.Reason = "Protect the document from unwanted changes";
                signature.ContactInfo = "The contact email is support@evopdf.com";
                signature.Location = "Development server";
                digitalSignaturePage.AddElement(signature);
            }

            // Save the PDF document in a memory buffer
            byte[] outPdfBuffer = pdfDocument.Save();

            // Send the PDF as response to browser

            // Set response content type
            Response.AddHeader("Content-Type", "application/pdf");

            // Instruct the browser to open the PDF file as an attachment or inline
            Response.AddHeader("Content-Disposition", String.Format("attachment; filename=Digital_Signatures.pdf; size={0}", outPdfBuffer.Length.ToString()));

            // Write the PDF document buffer to HTTP response
            Response.BinaryWrite(outPdfBuffer);

            // End the HTTP response and stop the current page processing
            Response.End();
        }

        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                string currentPageUrl = HttpContext.Current.Request.Url.AbsoluteUri;
                string rootUrl = "http://www.evopdf.com/demo/";

                htmlStringTextBox.Text = System.IO.File.ReadAllText(Server.MapPath("~/DemoAppFiles/Input/HTML_Files/Digital_Signatures.html"));
                baseUrlTextBox.Text = rootUrl + "DemoAppFiles/Input/HTML_Files/";

                sampleCodeLiteral.Text = System.IO.File.ReadAllText(Server.MapPath("~/DemoAppFiles/Input/Code_Samples/CSharp/AspNet/HTML_to_PDF/PDF_Security/Digital_Signatures.html"));
                descriptionLiteral.Text = System.IO.File.ReadAllText(Server.MapPath("~/DemoAppFiles/Input/Descriptions/AspNet/HTML_to_PDF/PDF_Security/Digital_Signatures.html"));

                Master.CollapseAll();
                Master.ExpandNode("HTML_to_PDF");
                Master.ExpandNode("PDF_Security_Features");
                Master.SelectNode("Digital_Signatures");
            }
        }

        protected void demoMenu_MenuItemClick(object sender, MenuEventArgs e)
        {
            switch (e.Item.Value)
            {
                case "Live_Demo":
                    demoMultiView.SetActiveView(liveDemoView);
                    break;
                case "Description":
                    demoMultiView.SetActiveView(descriptionView);
                    break;
                case "Sample_Code":
                    demoMultiView.SetActiveView(sampleCodeView);
                    break;
                default:
                    break;
            }
        }
    }
}

<!DOCTYPE html>
<html>
<head>
    <title>Add Digital Signatures in PDF</title>
</head>
<body style="font-family: 'Times New Roman'; font-size: 14px">
    <span style="font-size: 24px; font-weight: bold">Digital Signatures</span><br />
    <br />
    <span>The image and the text below will become a link to digital signature properties:</span>
    <br />
    <br />
    <div data-mapping-enabled="true" data-mapping-id="digital_signature_element" style="width: 320px; padding: 5px 5px 5px 5px; border: 2px solid royalblue">
        <span style="font-size: 16px; font-weight: bold; text-decoration: underline; color: navy">Click to open the digital signature properties</span><br />
        <br />
        <img alt="Logo Image" style="width: 300px" src="img/logo.jpg" />
    </div>
    <br />
    <br />
</body>
</html>