22 Jul
1993
22 Jul
'93
4:54 a.m.
A very good posting, Karl, but I will note in the literature these are called "covert" channels, not "subliminal" channels.
Covert channels are signaling techniques which bypass secrecy classification, right? e.g. twiddling with free disk and other system parameters. Passing messages in digital signatures, which I've always seen called "subliminal channels", could of course be used as a covert channel if the OS permits signatures on material accessible to lower-classification folk.
Perry
Eli ebrandt@jarthur.claremont.edu