Skip to main content
H
Horvath Wolf
Participant
January 9, 2022
質問

Unable to apply a Document time stamp to a Certified PDF

  • January 9, 2022
  • 返信数 1.
  • 3189 ビュー

Applying a Document time stamp works on digitally signed documents, even if the document has been locked after applying a digital signature. This is expected behavior in order to comply with the requirements of PAdES-B-LTA.

However, if a document was first certified with a digital signature, I won't be able to apply a Document time stamp to it afterwards. Why is that? Am I missing something?

Applying a Document time stamp on such documents while retaining compliance, in my case with eIDAS, is still achievable with other tools based on the DSS framework, however not through Adobe Reader/Acrobat.

 

Is there a way to achieve this functionality solely by using Adobe PDF solutions?

このトピックへの返信は締め切られました。

返信数 1

Amal.
Community Manager
Amal.Community Manager
Community Manager
January 10, 2022

Hi Ivan,

 

Hope you are doing well and sorry to hear that.

 

It is the designed behavior of Adobe Acrobat/Reader DC application. Once the PDF file is signed and the signature process is completed it gets locked for further editing. For more information about editing a signed PDF please check  the help page https://helpx.adobe.com/acrobat/kb/edit-signed-PDF.html

 

Regards

Amal

H
Horvath Wolf作成者
Participant
January 11, 2022

Hi Amal, and thank you for answering my question. I understand now that it is not possible to apply a document time stamp to a certified/signature-locked PDF. That is unfortunate, though, because while I understand that locking the document is meant to disable/discourage any changes being made to it, I don't really see how applying a document time stamp would constitute a change to the document. In other words, I don't think that applying a document time stamp would result in invalidating the applied signature(s), but I may be wrong there...

H
Horvath Wolf作成者
Participant
April 8, 2022

Actually this is definitely a serious bug.

 

Digitally signed documents become invalid after the signer's certificate expires. To extend document's validity, it's necessary to add verification info and fresh document timestamp.

 

If Acrobat disallows this, all documents signed in Acrobat become invalid after certificate expiration, without any possibility to extend their validity.


I agree this is a serious issue for locked documents.

 

I just tested this again on Acrobat Pro DC version 2022.001.20085 on a blank document which I digitally signed and locked in the process of signing it. After applying the signature, there is no right-click option to "Add Signature Information", and the options to sign/timestamp/certify are all greyed-out and unavailable.

 

I hope this "designed behaviour" either gets corrected in the future updates, or at least Adobe gives us an explanation of why is it designed like this.

 

Screenshots:

 

契約条件Accessibility statement
Using the community Terms of use Privacy Cookie preferences Do not sell or share my personal information ad choicesAdChoices