It is possible but be wary of some traps. Using a symetric algorithm could be problematic because you're going to need that key embedded in your cgi somehow and if the bad hats have access to the "data" disk, then they probably also have access to the "cgi" disk - making that symetric approach suspect.

You could look into using an asymetric algorithm, take a look at my (toot toot) GPG Tutorial for ideas on how to set up a two-user encryption scheme.

-derby