Linux Softwares to Pdf encryption

jPdf Tweak is a versatile, cross-platform Java Swing application designed for manipulating PDF files. It offers a range of functionalities including combining, splitting, rotating, reordering, watermarking, encrypting, signing, and other essential PDF adjustments.

PDF Chain is a user-friendly graphical interface (GUI) for the powerful command-line PDF Toolkit (pdftk). It simplifies common PDF manipulation tasks such as merging, splitting, collating, encrypting, and managing metadata without requiring direct command-line interaction.

Master PDF Editor is a comprehensive PDF editing suite for Windows, macOS, and Linux. It empowers users to create, edit, view, annotate, and sign PDF documents with a robust set of tools.