Computationally Efficient Covert Communication

TL;DR

This paper introduces the first computationally efficient coding scheme for covert communication over BSCs, achieving reliable, undetectable transmission at optimal rates with practical complexity.

Contribution

It presents the first tractable codes for covert communication over BSCs that maintain reliability, covertness, and optimal throughput, overcoming previous computational limitations.

Findings

Achieves reliable and covert transmission of O(√n) bits over n channel uses.

Provides codes with polynomial-time encoding and decoding algorithms.

Maintains optimal throughput while ensuring computational efficiency.

Abstract

In this paper, we design the first computationally efficient codes for simultaneously reliable and covert communication over Binary Symmetric Channels (BSCs). Our setting is as follows: a transmitter Alice wishes to potentially reliably transmit a message to a receiver Bob, while ensuring that the transmission taking place is covert with respect to an eavesdropper Willie (who hears Alice's transmission over a noisier BSC). Prior works show that Alice can reliably and covertly transmit O(\sqrt{n}) bits over n channel uses without any shared secret between Alice and Bob. One drawback of prior works is that the computational complexity of the codes designed scales as 2^{\Theta(\sqrt{n})}. In this work we provide the first computationally tractable codes with provable guarantees on both reliability and covertness, while simultaneously achieving the best known throughput for the problem.