//// This code is part of Document Solutions for PDF .NET demos.// Copyright (c) MESCIUS inc. All rights reserved.//using System.IO;using System.Security.Cryptography.X509Certificates;
using GrapeCity.Documents.Pdf;

namespace DsPdfWeb.Demos{    // This sample shows how to sign an existing PDF file containing    // an empty signature field with a signature that complies with    // PAdES (PDF Advanced Electronic Signatures) B-T level standard.    public class SignPAdESBT    {        public int CreatePDF(Stream stream)        {            var doc = new GcPdfDocument();            using var s = File.OpenRead(Path.Combine("Resources", "PDFs", "SignPAdESBT.pdf"));            doc.Load(s);
            var pfxPath = Path.Combine("Resources", "Misc", "DsPdfTest.pfx");            var cert = new X509Certificate2(pfxPath, "qq");            var sp = SignatureProperties.CreatePAdES_B_T(new TimeStamp("https://freetsa.org/tsr"), cert);            sp.SignatureAppearance.Caption = "PAdES B-T";            sp.SignatureField = doc.AcroForm.Fields[0];            doc.Sign(sp, stream);
            // Done.            return doc.Pages.Count;        }    }}