How to Enable/Disable re-sign pdf after pdf has been signed with syncfusion

[Clement GIL]

Hi,

I would like to know if there is an option/property that allows me to re-sign a PDF.

For example if value set to true => so I can re-sign with Adobe reader for example

If value set to false => no one can re-sign after the first signature done with syncfusion

Thanks for your help

[Sowmiya Loganathan]

Hi Clement, 

Thank you for contacting Syncfusion support.  

We can achieve your requirement by using the properties “Certificated” and “DocumentPermissions” of PdfSignature.  If we set document permission as ForbidChanges and enable the Certificated property, the first signature fails if we resign the document.  

Code Snippet:  

//Creates a digital signature 

PdfSignature signature = new PdfSignature(document, page, pdfCert, "Signature"); 

 

//Sets signature information 

signature.Bounds = new RectangleF(bounds); 

 

signature.Certificated = true; 

signature.DocumentPermissions = PdfCertificationFlags.ForbidChanges; 

Output document screenshot:  

   

At the same time, if we choose document permission as AllowComments/AllowFormFill and enable the Certified property, the first signature is valid even if we sign another signature to the document. 

Code Snippet: 

//Creates a digital signature 

PdfSignature signature = new PdfSignature(document, page, pdfCert, "Signature"); 

 

//Sets signature information 

signature.Bounds = new RectangleF(bounds); 

 

signature.Certificated = true; 

signature.DocumentPermissions = PdfCertificationFlags.AllowFormFill | PdfCertificationFlags.AllowComments; 

Output document screenshot:  

 

Note: The document permissions only work when we enable the Signature.Certificated  property. 

Kindly try the above solution in your end and let us know the if it satisfies your requirement.  

Regards, 

Sowmiya Loganathan 

[Clement GIL]

Ok thanks for you help. 

Best Regards.

Clément

[Tim]

I am trying to do this very thing, and I am generating this exception:

System.ArgumentException
  HResult=0x80070057
  Message=The document may contain at most one author signature!
  Source=Syncfusion.Pdf.Portable
  StackTrace:
   at Syncfusion.Pdf.Security.PdfSignature.set_Certificated(Boolean value)
.....omitted

[Irfana Jaffer Sadhik]

Hi Tim,

We have tried to reproduce the reported issue, but it is working properly on our end. We suspect that the problem may be due to that document specific.

we request you to share the complete code snippet or modified sample, output document, issue screenshot, product version, environmental details (OS, Bit version, culture settings) to replicate the issue on our end. So that it will be helpful for us.

Regards,

Irfana J.