bitwisexor: For starters the white paper you found (as a cache copy-meaning its been withdrawn from the site now!!) was based on Acrobat 5
The latest Version is now Version 7.0 Professional, and the technologies have moved on at serious pace since version 5.
Version 7 has features that would even keep the most professional (cracker) at bay for a while, but like I said THERE ARE ALWAYS SIDE STEPS to all security issues.
Version 7.0 Professional however will keep 99% of people from Editing, Selecting and even Printing your document if you so wish!!