Covert Communication Over Adversarially Jammed Channels

Suppose that a transmitter Alice potentially wishes to communicate with receiver Bob over an adversarially jammed binary channel. An active adversary James eavesdrops on their communication symmetric channel (BSC( q)), and may maliciously flip (up to) certain fraction p of transmitted bits based his observations. We consider setting where the must be simultaneously covert as well reliable, i.e., should unable accurately distinguish whether or not is communicating, while able correctly recover Alice's message high probability regardless adversarial jamming strategy. show that, unlike passive adversaries, against adversaries requires have shared key (of length at least Ω(logn)) even when has better than James. present lower upper bounds information-theoretically optimal throughput function parameters, desired level covertness, amount available. These match for wide range parameters interest. also develop computationally efficient coding scheme (based concatenated codes) available Ω(√n logn), further this can implemented much less assumed bounded.