Can I encrypt PDF files in AIX 5.3?
Sorry, but that begs the answer:
Yes, you can.
Seriously, what exactly do you want to achieve? You can of course encrypt all sorts of files using the "openssl" command (see its man page for details) if you have the "openssl" package installed. You can download it as rpm package from the "Linux toolbox for AIX" from IBMs page.
I hope this helps.
bakunin