Well, there is visual cryptography in various forms, and if one databank is not secure enough, make it two or three- parole officier+National Databank or something, thats called secret-sharing-cryptography. It is possible to combine both, and even have them at a simple enough level to not require PCs. Of course, for visual cryptography you need a fast way to recreate the visual secrets- computing and graphing polynoms for thirty minutes every twelve-ish hours is a serious waste of time...