pdfcrack is a command line, password recovery tool for PDF-files.
PDFCrack is a GNU/Linux (other POSIX-compatible systems should work too) tool
for recovering passwords and content from PDF-files. It is small,
command line driven without external dependencies.
The application is Open Source (GPL).
Enable snaps on Kubuntu and install pdfcrack-simosx
Snaps are applications packaged with all their dependencies to run on all popular Linux distributions from a single build. They update automatically and roll back gracefully.
Snaps are discoverable and installable from the Snap Store, an app store with an audience of millions.