You can secure it so they can't edit it, print it, or copy and paste. We routinely do this for our PDFs, usually invoices and proposals that we don't want them to change or share (well, yes - they can forward the entire thing, but then it still has our copywrite). OCR is an entirely different problem, pretty much impossible to stop.

I think most of the security bits require 5 or later to open at all; 4 and before won't open them.

-jk