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PDF digital signature and timestamp are the best ways to protect your PDF files from being forged. Syncfusion Essential PDF is a .NET 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.Forms, 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.
The Syncfusion .NET PDF library provides a completely customizable appearance for its e-signature. The content of the signature can be images, texts, graphics, and shapes.
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.
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.
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.
Easily add the digital signature to a PDF document using a few simple lines of C# code as demonstrated below. Also explore our .NET PDF Example that shows how to create and modify PDF files from C# with 5 lines of code on different platforms.
using Syncfusion.Pdf;
PdfDocument document = new PdfDocument(); //Creates a new PDF document
PdfPageBase page = document.Pages.Add(); //Adds a new page
PdfGraphics graphics = page.Graphics;
PdfCertificate pdfCert = new PdfCertificate(@"PDF.pfx", "syncfusion"); //Creates a certificate instance from PFX file with private key
PdfSignature signature = new PdfSignature(document, page, pdfCert, "Signature"); //Creates a digital signature
PdfBitmap signatureImage = new PdfBitmap(@"signature.jpg"); //Sets an image for signature field
signature.Bounds = new RectangleF(new PointF(0, 0), signatureImage.PhysicalDimension); //Sets signature information
signature.ContactInfo = "johndoe@owned.us";
signature.LocationInfo = "Honolulu, Hawaii";
signature.Reason = "I am author of this document.";
graphics.DrawImage(signatureImage, 0, 0); //Draws the signature image
document.Save("Output.pdf"); //Saves and closes the document
document.Close(true);Imports Syncfusion.Pdf
Dim document As New PdfDocument() //Creates a new PDF document
Dim page As PdfPageBase = document.Pages.Add() //Adds a new page
Dim graphics As PdfGraphics = page.Graphics //Creates a certificate instance from PFX file with private key
Dim pdfCert As New PdfCertificate("PDF.pfx", "syncfusion")
Dim signature As New PdfSignature(document, page, pdfCert, "Signature") //Creates a digital signature
Dim signatureImage As New PdfBitmap("signature.jpg") //Sets an image for signature field
signature.Bounds = New RectangleF(New PointF(0, 0), signatureImage.PhysicalDimension) //Sets signature info
signature.ContactInfo = "johndoe@owned.us"
signature.LocationInfo = "Honolulu, Hawaii"
signature.Reason = "I am author of this document."
graphics.DrawImage(signatureImage, 0, 0) //Draws the signature image
document.Save("Output.pdf") //Saves and closes the document
document.Close(True)CASE STUDY
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