Covert channels are channels not intended for information transfer. A subliminal channel allows one to hide a secret message inside an authenticator. An abuse enables a participant to us a cryptosystem for a different purpose than intended. In this project, techniques guaranteeing that such abuses are impossible are being studied. The main open problems addressed are: (1) can unconditionally secure authentication schemes be made subliminal- free, and generally, which systems can be made abuse-free; (2)which non-trivial systems can be made abuse-free when using only a passive warden; (3) can the results be extended to analog and digital covert channels?