olemus
krüptograafias: peitkanal salasideks normaalse ilmega sides mingi ebaturvalise kanali kaudu
= a covert channel used to communicate secretly in normal looking communication over an insecure channel

ülevaateid
https://en.wikipedia.org/wiki/Subliminal_channel

https://cs.gmu.edu/~zduric/cs803/Simmons.pdf

https://www.freehaven.net/anonbib/cache/ringstwice07.pdf