Question

I’m trying to digitally sign a PDF file using THIS project as an example.

When it executes st.Close(); I am getting the infamous ‘Object reference not set to instance of an object’.

I have no idea of why this is happening, st is an instance of an object and it is used above. This exception is happening inside .Close() and as I do not have the source code i can only try to guess why…

All i can say is that:

1. The original PDF is being successfully read.
2. An empty pdf is being generated (I guess the .Close() will write the file).
3. My certificate is being loaded, but I am not sure it’s the right way to do it.

Here is How I’m loading the certificate:

private void processCert(X509Certificate2 card) {     X509CertificateParser cp = new org.bouncycastle.x509.X509CertificateParser(card.RawData);     chain = new org.bouncycastle.x509.X509Certificate[] { cp.ReadCertificate() }; } 

This is how I am trying to sign the PDF.

public string Sign(string SigReason, string SigContact, string SigLocation, bool visible) {     string bugLog ='';     try     {         PdfReader reader = new PdfReader(this.inputPDF);          //Activate MultiSignatures         PdfStamper st = PdfStamper.CreateSignature(reader, new FileStream(this.outputPDF, FileMode.Create, FileAccess.Write), '\0', null, true);          FileStream(this.outputPDF, FileMode.Create, FileAccess.Write), '\0');           st.MoreInfo = this.metadata.getMetaData();          st.XmpMetadata = this.metadata.getStreamedMetaData();          PdfSignatureAppearance sap = st.SignatureAppearance;          sap.SetCrypto(this.myCert.Akp, this.myCert.Chain, null, PdfSignatureAppearance.WINCER_SIGNED);          sap.Reason = SigReason;         sap.Contact = SigContact;         sap.Location = SigLocation;          if (visible)            sap.SetVisibleSignature(new iTextSharp.text.Rectangle(100, 100, 250, 150), 1, null);          st.Close();     }     catch (Exception e)     {         bugLog += ' ERROR Sign: ' + e.Message;     }      return buglog;   } 

Has anyone got a though on why I am getting this exception, or what should i do to overcome this?

The iTextSharp Documentation has not been much help…

Answer 1

I’ve now manage to make this work 🙂 Some minor changes to this example did the trick 😉

http://itextpdf.sourceforge.net/howtosign.html#signextitextsharp2