Just remember to stay away from published standards and methods.
QuoteJust remember to stay away from published standards and methods. If you're really serious about security, this should not apply to the encryption algorithm you use - you need something devised by a cryptographer and peer reviewed. It is a common conceit to suppose that you can devise your own secure encryption method, but it is highly unlikely that you can.
@karlok - a rolling code can be defeated fairly easily once you recognize that it is being used. A replay attack just replays the last message and would of course fail. Actually determining the rolling key algorithm will allow you to modify the next message and "play" it with the right key.