PDF Unlocker is a utility application to manage permissions on PDF files. It allows the users to securely lock the PDF files with limited access rights using a owner password. The PRO version also lets the users to encrypt the PDF using a user password. With PDF Unlocker you can also remove all security and access parameters from the file hence completely unlocking it.
On locking the file, a new file will be created in the same directory with LOCKED appended to its name. And when the file is unlocked, it will create a new file in the same directory with UNLOCKED appended to its name. The permissions on the original file are preserved.