"Due to deep-seated Cold War fears, encryption is highly regulated by
the U.S. Departments of State and Commerce, which refuse to license any secure encryption product for export unless it utilizes "key
recovery", a law enforcement code word for the ability of third-parties (not originally intended to receive the message) to easily
decrypt information."
http://www.eff.org/descracker/
So 666 could possibly be used for "key recovery" ;) Cool eh? Hehe...