Verifying digital signature on PDF

What is the best way to verify digital signature on downloaded PDF files? I am using 19.04.

Solution 1:

As of now, the best solution I found is the Adobe Reader DC snap, which uses wine: https://snapcraft.io/acrordrdc . Only, take care of not disconnecting the network for this snap, as the installer suggests doing to avoid updates (possibly not working), because this obviously prevents signature verification.

I have been trying the "native" Adobe Reader 9, Master PDF Editor and PDF Studio Viewer but I found them incomplete. Adobe Reader 9 apparently has an outdated verification method, Master PDF Editor appears to verify the signature but still shows a "?" rather than a "Valid signature" mark in my PDF, and PDF Studio Viewer marks the (supposedly valid) signature as Invalid because of not supporting the signature handler (Adobe.PPKLite::ETSI.RFC3161).

This is based on PDFs from only one authority, but for non-experts in digital signatures and certification methods, it appears that the snap is the best option if one only wants to verify a signature and go on.