Overview of covert communications through networks
Michael A. Caloyannides · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2002
Covert communications through digital networks are a small subset of covert channel communications through all other networks such as human contacts, postal, telephone, ham radio and other networks. The repertoire of options available to anyone for covert communications through digital networks is limited only by imagination; covert communications are therefore inherently uncontrollable.