So far I have been unable to find any tools on Linux (preferably FOSS) which will display a digital signature when viewing a PDF file and possibly also allow verification of the validity of that signature.

Can anyone name any such tools?

Is it true that many of the popular default PDF readers of Linux desktops such as Gnome or KDE just ignore digital signatures when viewing PDF files?

  • 1
    I'm not sure about the PDF angle, but when looking into card readers there was deep conflict. The manufacturing and standards bodies both want to keep some control over the interfaces with these devices, so their license terms have been in conflict with some of the popular Open Source licenses. I'm referring to PKCS#11 in particular, but I've also seen generally low adoption of Smart Cards with other crypto software.
    – nbering
    Jul 24, 2018 at 12:38
  • @nbering Adoption is typically a function of usefulness. As I wrote, applications are popping up; of course slowly but surely, i.e. so called eJustice as well as medical applications. And while the license issue may be there, I think it doesn't actually apply to checking a signature, does it. But most PDF readers which are not coming from Adobe don't care for digital signatures at all.
    – TorstenS
    Jul 24, 2018 at 13:14
  • 1
    This post lacks focus, which makes it difficult to answer. Your question ultimately is: are FOSS PDF readers capable of displaying or verifying digital signatures? That's not a security question. The rest of your post seems to be wanting to start a discussion around the other issues you raised. If you can focus your question, edit it with some changes, and we can look at reopening it.
    – schroeder
    Jul 29, 2018 at 8:21
  • MuPDF - artifex.com/mupdf-technical-information
    – symcbean
    Jul 30, 2018 at 15:11


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