RFE: add signature validation to atril

[rathann]

Expected behaviour

Atril recognizes PAdES signatures in PDF and is able to validate them.

Actual behaviour

Atril doesn't recognize PAdES signatures in PDF and there's no option to validate them.

Steps to reproduce the behaviour

Download example-signed.pdf and open in Atril. Check File->Properties.

MATE general version

1.26.0

Package version

1.26.0-2.fc36

Linux Distribution

Fedora 36

Link to bugreport of your Distribution (requirement)

https://bugzilla.redhat.com/show_bug.cgi?id=2130483

Additional information

Okular supports signatures (https://invent.kde.org/graphics/okular/-/merge_requests/296) thanks to poppler already supporting this: https://gitlab.freedesktop.org/poppler/poppler/-/merge_requests/656 . Here's the MR for evince okular: https://invent.kde.org/graphics/okular/-/merge_requests/296 .

[gszy]

I think the Evince MR link should be this instead: https://gitlab.gnome.org/GNOME/evince/-/merge_requests/448

[rathann]

Thanks for the Evince MR link. I actually meant okular, so edited.