//新建一個(gè)PDF文檔對象，再添加一個(gè)新頁面。
PdfDocument doc = new PdfDocument();
doc.Pages.Add();
//加載一個(gè)PDF證書      
PdfCertificate cert = new PdfCertificate(@"C:\Users\Administrator\Desktop\gary.pfx", "e-iceblue");

//添加數(shù)字簽名
var signature = new PdfSignature(doc, doc.Pages[0], cert, "Requestd1");
//設(shè)置數(shù)字簽名的位置
signature.Bounds = new RectangleF(new PointF(280, 600), new SizeF(260, 90));

signature.IsTag = true;

signature.DigitalSignerLable = "Digitally signed by";
signature.DigitalSigner = "Gary for Test";

signature.DistinguishedName = "DN:";
signature.LocationInfoLabel = "Location:";
signature.LocationInfo = "London";

signature.ReasonLabel = "Reason: ";
signature.Reason = "Le document est certifie";

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

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

signature.Certificated = false;

signature.ConfigGraphicType = ConfiguerGraphicType.TextSignInformation;

signature.DocumentPermissions = PdfCertificationFlags.ForbidChanges;

//保存文檔
doc.SaveToFile("sample.pdf");
//打開文檔
System.Diagnostics.Process.Start("sample.pdf");