I am a Linux desktop user.
Someone sends me a PDF file which is digitally signed. It is supposed to be signed using some kind of government / regulated body / official institution issued certificate.
Is there a way that I, as a typical end-user, could determine whether the signature is valid?
I know Windows Acrobat Reader works to some extend, though even there it's not really clear about the validity of a signature as opposed to the fact that it's there and seems to be from XYZ.
Best Answer
I spent few hours experimenting with that and found that:
1)
pdfsig
command from poppler-utils package is able to validate PDF signature. Usage is simple:But for me it works only for visible signatures (version 0.62.0 on Fedora 28). For invisible signatures it shows:
2) Master PDF Editor is a GUI tool which shows and validates signatures as shown on the picture below and it is enough to have free version.![Master PDF Editor - Signatures](https://i.stack.imgur.com/1rRy3.png)
3) LibreOffice Draw is able to show and validate signature using File -> Electronic signatures -> Electronic signatures. But in my case it again shows only visible signatures.