EVO HTML to PDF Converter allows you to add digital signatures to the generated PDF document. In order to add digital signatures you need a certificate with private and public keys. These certificates are usually stored in a .pfx or a .p12 file in PKCS#12 format and they can be password protected. A digital signature is represented by a EvoPdf.HtmlToPdfClientDigitalSignatureElement object which can be placed in any position in a PDF page. Below is a complete example of adding a digital signature to a PDF document.
Code Sample - Add A Digital Signature to Generated PDF Document
C#
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 PDF document Document pdfDocument = null; if (radioButtonUseTcpService.Checked) pdfDocument = new Document(serverIP, serverPort); else pdfDocument = new Document(true, textBoxWebServiceUrl.Text); // Set optional service password if (textBoxServicePassword.Text.Length > 0) pdfDocument.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 pdfDocument.LicenseKey = "4W9+bn19bn5ue2B+bn1/YH98YHd3d3c="; // Add a page to PDF document PdfPage pdfPage = pdfDocument.AddPage(); string htmlWithDigitalSignatureMarker = htmlStringTextBox.Text; string baseUrl = baseUrlTextBox.Text; // Add a HTML string with a marker for digital signature to PDF document HtmlToPdfElement htmlToPdfElement = new HtmlToPdfElement(htmlWithDigitalSignatureMarker, baseUrl); pdfPage.AddElement(htmlToPdfElement); string certificateFilePath = Server.MapPath(@"~/DemoAppFiles/Input/Certificates/evopdf.pfx"); // Create the digital signature DigitalSignatureElement signature = new DigitalSignatureElement(certificateFilePath, "evopdf", 0); signature.Reason = "Protect the document from unwanted changes"; signature.ContactInfo = "The contact email is support@evopdf.com"; signature.Location = "Development server"; pdfDocument.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(); }
HTML Code with a Region Marked to Become a Digital Signature
XML
<!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>