There is no mechanism for user permissions or password-protecting project files in After Effects itself.
You may have the ability to protect your files on the network, but you'd have to speak with whomever manages the shared render farm to find out if it's possible.
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting RenderBreak Blog - What I'm thinking when my workstation's thinking
Creative Cow Forum Host: Live & Stage Events