In this tutorial, I'll show you how to Implement Digital Sign in C#.NET. Digital signatures are a way of replacing the documents in the electronic document exchange

To play demo, you need to install Spire.Pdf from nuget package manager or you can download it directly from https://www.e-iceblue.com

public static void SignPdfFile(string sourceDocument, string destinationPath, string signatureFile, string password, string reason, string location)
{
    PdfDocument doc = new PdfDocument();
    doc.LoadFromFile(sourceDocument);
    PdfCertificate cert = new PdfCertificate(signatureFile, password);

    var signature = new PdfSignature(doc, doc.Pages[0], cert, "Signature");
    signature.Bounds = new RectangleF(new PointF(280, 600), new SizeF(260, 90));
    signature.IsTag = true;
    signature.DigitalSignerLable = "Digitally signed by";
    signature.DigitalSigner = "FoxLearn";
    signature.ConfigGraphicType = ConfiguerGraphicType.TextSignInformation;
    signature.DistinguishedName = "DN: FoxLearn, O=Tech Room, OU=FoxLearn, Email = tanhynh@gmail.com, C=US";

    signature.LocationInfoLabel = "Location:";
    signature.LocationInfo = location;

    signature.ReasonLabel = "Reason: ";
    signature.Reason = reason;

    signature.DateLabel = "Date: ";
    signature.Date = DateTime.Now;

    signature.ContactInfoLabel = "Contact: ";
    signature.ContactInfo = "123456789";

    signature.Certificated = false;

    signature.DocumentPermissions = PdfCertificationFlags.ForbidChanges;
    doc.SaveToFile(destinationPath);
}

This is a professional PDF component that is used to create, write, edit, process and read PDF files without any external dependencies in .NET applications.

Using this .NET PDF library, you can implement rich capabilities to create PDF files from scratch or process existing PDF documents entirely through C# or VB.NET without installing Adobe Acrobat.