column-level encryption

I have a requirement to do column-level encryption in an Informix 9.30.UC6 database. If possible, I'd like to avoid datablades (although Stored Procedures / Functions would be okay). In a perfect world it would be a fast algorithm. The encryption algorithm doesn't need to be super-secure -- just enough to mask the contents from the casual observer and keep the data in some format other than readable text. Has anyone already invented this wheel, such that I don't need to re-invent it? Any advice or assistance would be greatly appreciated. Oh, and I should mention that for this application, a "secret key" algorithm would be fine. A public key algorithm is probably overkill. Thanks! - Tom Girsch