How to Password Protect a PDF on Linux

Doing it on Linux

Open Firefox or Chrome and choose the file from your home directory. Then work through the same steps as anywhere else:

Open the document and go to the security settings.

Set an open password — this encrypts the contents with AES-256.

Choose permissions: allow or disallow printing, copying and further editing.

Export, and send the password through a different channel from the file itself.

Saving the finished file

When you export, the browser save dialog writes it wherever you point it. PDF, PNG and JPG are all available.

Why nothing needs installing

Encryption is genuine protection; permissions are an instruction that well-behaved readers respect. Do not rely on permissions alone.

Because it all runs in a browser tab, it also works on managed school and work devices where you cannot add software.