Covert Bits Through Queues
This addresses secure communication for scenarios requiring stealth against adversaries, representing a novel approach rather than an incremental improvement.
The paper tackled covert communication using queuing timing channels in the presence of a warden, achieving non-zero covert rates for exponential and general queues when a high-rate secret key is available, in contrast to models like Gaussian channels that yield zero covert rate.
We consider covert communication using a queuing timing channel in the presence of a warden. The covert message is encoded using the inter-arrival times of the packets, and the legitimate receiver and the warden observe the inter-departure times of the packets from their respective queues. The transmitter and the legitimate receiver also share a secret key to facilitate covert communication. We propose achievable schemes that obtain non-zero covert rate for both exponential and general queues when a sufficiently high rate secret key is available. This is in contrast to other channel models such as the Gaussian channel or the discrete memoryless channel where only $\mathcal{O}(\sqrt{n})$ covert bits can be sent over $n$ channel uses, yielding a zero covert rate.