Show signature in all pages of PDF using iTextSharp

Question

Hello I am wanting to show the digital signature on all pages of the PDF, I researched but only found a method that inserts an image on all pages, but my certificate has no image, can someone help me. Below, a piece of code:

sap.SetVisibleSignature( new iTextSharp.text.Rectangle( 10f, 10f, 110f, 30f ), reader.NumberOfPages, null );
sap.SignDate = DateTime.Now;
sap.Acro6Layers = true;
PdfSignature dic = new PdfSignature( PdfName.ADOBE_PPKMS, PdfName.ADBE_PKCS7_SHA1 );
dic.Date = new PdfDate( sap.SignDate );
signName = iTextSharp.text.pdf.security.CertificateInfo.GetSubjectFields( sap.Certificate ).GetField( "CN" );
dic.Name = signName;

if ( sap.Reason != null ) dic.Reason = sap.Reason;
if ( sap.Location != null ) dic.Location = sap.Location;

his code only shows the signature on the last page of the PDF.

Answer 1

I've taken a screen shot from the draft of the upcoming specification.

You're asking to have one signature that is represented by multiple widget annotations (one on each page). However, the spec says:

signature fields shall never refer to more than one annotation.

Whenever the spec uses the word shall , any PDF not obeying the spec is considered invalid. (In case the spec is only recommending something, the word should is used.)

Summarized: you're asking something that isn't allowed (for now: not recommended; in the future: forbidden).

Extra remark: a digital signature in a PDF covers the whole document. There is no use to put a visual mark on each page because that would encourage the misconception that digital signatures in PDF can be used to sign separate pages. The reason to add the one signature = one widget annotation in the ISO specification is also educational: whoever demands a widget annotation on every page for a single signature, proves that he or she doesn't understand the concept of digital signatures in PDF ;-)