Indeed you can decrypt files using pgp. You'll probably want to check out Crypt::OpenPGP, which gives plentiful explanations and nice and clear examples of what to do. And if you download it too, that would be be even better!
HTH
Ok, so, after searching there are a lot of options (83 hits for pgp). OpenPGP is one, and SimplePGP is one, and, and, and. Does anyone have any suggestions for the best one? Well, that's open ended. How about the best for a) large programs, b) quick small scripts?