The 50-cent word here is “steganography,” which per Wikipedia is “the art and science of writing hidden messages in such a way that no one, apart from the sender and intended recipient, suspects the existence of the message.” You may have heard, for instance, that you can encode a hidden message in, say, an image file, in such a way that no one who wasn’t looking for it would know that it’s there.
Well, this morning Danger Room linked to a post at IEEE Spectrum to the effect that Voice Over Internet Protocol (VOIP) is particularly susceptible to steganographic hijinks. Wired’s David Pierce put it this way:
There’s only the smallest possible time for interception to happen since all data is stored locally rather than redirected through a central server. Plus, since so much data is being sent back and forth, large messages can be sent without causing any alarm. Unlike an image or video, which can be downloaded and analyzed at anytime, there’s no way to get at and store files sent with VoIP.