Reliable, deniable, and hidable communication over multipath networks

We consider the scenario wherein a transmitter Alice wants to (potentially) communicate to the intended receiver Bob over a multipath network, i.e., a network consisting of multiple parallel links, in the presence of a passive eavesdropper Willie, who observes an unknown subset of links. A primary goal of our communication protocol is to make the communication 'deniable', i.e., Willie should not be able to reliably estimate whether or not Alice is transmitting any covert information to Bob. Moreover, if Alice is indeed actively communicating, her covert messages should be information-theoretically 'hidable' in the sense that Willie's observations should not leak any information about Alice's (potential) message to Bob - our notion of hidability is slightly stronger than the notion of information-theoretic strong secrecy well-studied in the literature. We demonstrate that deniability does not imply either hidability or (weak or strong) information-theoretic secrecy; nor does information-theoretic secrecy imply deniability. We present matching inner and outer bounds on the capacity for deniable and hidable communication over multipath networks.