Make it portable, and use cusom encryption

Firstly, try making it portable--this isn't a fixer-upper app, but portable is always good.
Secondly, it looks like this just uses Adobe's built-in security features. I could be mistaken, but if this is the case, you should really use your own custom encryption, which demands a password, then decrypts is and auto-enters a long alphanumeric code for the password to access the PDF in the way desired. This way a user can enter the user password they have, and the PDF will open only with user rights, or enter the master password, and it will be opened with owner rights.