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Forum Thread - View invisible signature

 May 21 2013 6:40 PM
If I add an invisible signature to a document using the Document.sign method. Is there a way to see that the document has been signed and if so by whom? Or do I need to add a visible signature to see that?
 May 22 2013 9:10 AM
Posted by a ceTe Software moderator

You can add visible or invisible digital signature to the PDF document without any problem. Please refer documentation on digital signing here.

The visible signature is visible on the PDF page and in the signature panel  within the navigation panel. The invisible signature is not visible on the PDF page but you can view the signature details in the signature panel within the navigation panel.

ceTe Software Support Team.
 May 28 2016 12:29 AM
i used itext sharp to get digital signature.

but after signed
it is in invisible mode.
please help me to make signature as visible mode

this the following code:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.IO;

using System.Security;
using System.Security.Cryptography;
using System.Security.Cryptography.X509Certificates;

using iTextSharp.text.pdf;

namespace Saturday
    public partial class Form1 : Form
        public Form1()

        private SecureString GetSecurePin(string PinCode)
            SecureString pwd = new SecureString();
            foreach (var c in PinCode.ToCharArray()) pwd.AppendChar(c);
            return pwd;

        private void button1_Click(object sender, EventArgs e)
            X509Store store = new X509Store(StoreLocation.CurrentUser);
            X509Certificate2 cert = null;
            //manually chose the certificate in the store
            X509Certificate2Collection sel = X509Certificate2UI.SelectFromCollection(store.Certificates, null, null, X509SelectionFlag.SingleSelection);
            if (sel.Count > 0)
                cert = sel[0];
                MessageBox.Show("Certificate not found");

        private void SignWithThisCert(X509Certificate2 cert)

                 OpenFileDialog b = new OpenFileDialog();
                 textBox1.Text=  openFileDialog1.FileName;
            string SourcePdfFileName = textBox1.Text;
            string DestPdfFileName = textBox1.Text + "-Signed.pdf";
            Org.BouncyCastle.X509.X509CertificateParser cp = new Org.BouncyCastle.X509.X509CertificateParser();
            Org.BouncyCastle.X509.X509Certificate[] chain = new Org.BouncyCastle.X509.X509Certificate[] { cp.ReadCertificate(cert.RawData) };
            IExternalSignature externalSignature = new X509Certificate2Signature(cert, "SHA-1");
            PdfReader pdfReader = new PdfReader(SourcePdfFileName);
            FileStream signedPdf = new FileStream(DestPdfFileName, FileMode.Create);  //the output pdf file
            PdfStamper pdfStamper = PdfStamper.CreateSignature(pdfReader, signedPdf, '\0');
            PdfSignatureAppearance signatureAppearance = pdfStamper.SignatureAppearance;
            //here set signatureAppearance at your will
            signatureAppearance.Reason = "Because I can";
            signatureAppearance.Location = "My location";

            signatureAppearance.SignatureRenderingMode = PdfSignatureAppearance.RenderingMode.DESCRIPTION;
            MakeSignature.SignDetached(signatureAppearance, externalSignature, chain, null, null, null, 0, CryptoStandard.CMS);
            //MakeSignature.SignDetached(signatureAppearance, externalSignature, chain, null, null, null, 0, CryptoStandard.CADES);




 May 31 2016 9:55 AM
Posted by a ceTe Software moderator

It is not possible to make the invisible signature present in the PDF visible using any of our DynamicPDF APIs. You can remove the invisible signature from the existing PDF and add new visible signature using latest DynamicPDF Merger API. Below is the code sample for it. If you would like to evaluate latest version 8 product then you can download the evaluation edition from our website here.

            //Code for removing the invisible signature.
            PdfDocument pdf = new PdfDocument("Path for input PDF");
            MergeDocument document = new MergeDocument(pdf);
            int c=document.Form.Fields.Count;
            document.Form.Fields[0].Output = FormFieldOutput.Remove;
            //Code to add visible signature.
            Signature signature2 = new Signature("MySigFieldNew", 10, 10, 300, 100);
            Certificate certificate2 = new Certificate(@"Path for the certificate file", "password");
            document.Sign("MySigFieldNew", certificate2);

ceTe Software Support Team.

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