PDF Digital Signature & Timestamp | Xamarin PDF library

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Overview

PDF digital signature and timestamp are the best ways to protect your PDF files from being forged. Syncfusion Essential PDF is a Xamarin PDF library that helps you add digital signature and time stamp to your PDF files in any .NET application, whether it is on Windows Forms, WPF, ASP.NET (web forms, MVC, Core), or even UWP, Xamarin.Android, and Xamarin.iOS. Syncfusion provides many ways to digitally sign a document: X509 certificates, such as .pfx files with private keys and also supports hardware security modules (HSM), Online Certificate Status Protocol (OCSP), certificate revocation lists (CRL), and Windows Certificate Store for authenticity and integrity.

Customize Appearance

The Syncfusion Xamarin PDF library provides a completely customizable appearance for its e-signature. The content of the signature can be images, texts, graphics, and shapes.

Custom Appearance

LTV

Long-Term Validation (LTV)

LTV signatures allow you to check the validity of a signature long after signing the document. All the required elements for signature validation must be embedded in the signed PDF to use LTV.

Creating an LTV enabled PDF documentation

Timestamp PDF

It is possible to include the date and time of your signing the PDF as part of your certificate-based digital signature. A timestamp helps you establish when you signed the PDF and reduces the chance of an invalid signatures. Syncfusion Essential PDF makes time-stamping a PDF document possible with only a few lines of code.

Creating a PDF with a time stamp documentation

Timestamp

Certificate details

Certificate Details

You can also get or retrieve the digitally signed certificate details like subject, author, and expiry date. Based on the expiry date, you can digitally sign the PDF with valid certificate again.

Additional features of digital signatures and timestamps

Sign existing PDFs with digital signatures.
Add multiple digital signatures to a PDF.
Add signature validation to a PDF.
Time-stamp an existing PDF document.
Time-stamp a PDF without a certificate.

PDF Digital Signature Code Example

Easily add the digital signature to a PDF document using a few simple lines of C# code as demonstrated below. Also explore our Xamarin PDF Example that shows how to create and modify PDF files from C# with 5 lines of code on different platforms.

c#
using Syncfusion.Pdf;

//Creates a new PDF document

PdfDocument document = new PdfDocument();

//Adds a new page

PdfPageBase page = document.Pages.Add();

PdfGraphics graphics = page.Graphics;

//Creates a certificate instance from PFX file with private key

PdfCertificate pdfCert = new PdfCertificate(@"PDF.pfx", "syncfusion");

//Creates a digital signature

PdfSignature signature = new PdfSignature(document, page, pdfCert, "Signature");

//Sets an image for signature field

PdfBitmap signatureImage = new PdfBitmap(@"signature.jpg");

//Sets signature information

signature.Bounds = new RectangleF(new PointF(0, 0), signatureImage.PhysicalDimension);

signature.ContactInfo = "johndoe@owned.us";

signature.LocationInfo = "Honolulu, Hawaii";

signature.Reason = "I am author of this document.";

//Draws the signature image

graphics.DrawImage(signatureImage, 0, 0);

//Save and closes the document. 

MemoryStream stream = new MemoryStream();

document.Save(stream);

document.Close(true);