How to verify if signature in pdf has expired?

Question

Hi,In my application I need to re-signature all documents that have expired certificates.How can I check if document's signature's certificate has expired?

Prakash Kumar D · Answer

Hi Jan, 
 
Please find the below details. 
 




In my application I need to re-signature all documents that have expired certificates. 
 

We can add a digital signature (re-sign) in existing PDF documents by using the following code example. 
 




//Loads the PDF document with signature field. 
PdfLoadedDocument loadedDocument = new PdfLoadedDocument("input.pdf"); 
 
//Set incremental update 
loadedDocument.FileStructure.IncrementalUpdate = false; 
 
//Gets the page. 
PdfLoadedPage page = loadedDocument.Pages[0] as PdfLoadedPage; 
 
//Get the existing signature field. 
PdfLoadedSignatureField signatureField = loadedDocument.Form.Fields[0] as PdfLoadedSignatureField; 
 
//Create a new PDF certificate. 
PdfCertificate certificate = new PdfCertificate(@"PDF.pfx", "syncfusion"); 
 
//Create new PdfSignature. 
signatureField.Signature = new PdfSignature(loadedDocument, page, certificate, "signature1", signatureField); 
 
//Saves the certified PDF document. 
loadedDocument.Save(@"Output.pdf"); 
 
//Close the document. 
loadedDocument.Close(true);    
                        
 
Please refer the following documentation for further details. https://help.syncfusion.com/file-formats/pdf/working-with-digitalsignature#signing-an-existing-document  
 


How can I check if document's signature's certificate has expired? 
 

 
Currently, we do not have support for retrieving certificate details from existing signed PDF documents. We will include this feature in our Volume 4 main release, which will be available in December 2018 tentatively. 
 
 
Regards, 
Prakash Kumar

Jan Grzybowski · Answer

Do you have more percise date of the update?New law regulations are comming in January 2019 and we want to prepare for them.

Prakash Kumar D · Answer

Hi Jan, 
 
Thank you for updating us. 
 
A support incident to track the status of this feature has been created under your account. Please log on to our support website to check for further updates 
  
http://www.syncfusion.com/Account/Logon?ReturnUrl=%2fsupport%2fdirecttrac  
  
Please let me know if you have any questions. 
 
Regards, 
Prakash Kumar