An Extensible Covert Communication Scheme Over the AWGN Channel With Feedback

We consider a problem of communication over a physically-degraded additive white Gaussian noise wiretap channel. A covertness constraint is imposed, which says that the output at the wiretapper must statistically resemble pure noise. Previous works have shown that the total amount of information that can be transmitted over n uses of the channel is proportional to root n, but the communication schemes in those works are designed to transmit only one message of predetermined length. We propose a feedback-aided scheme that, at the cost of less-than-optimal message length, is easily extensible to transmitting multiple messages and an unbounded amount of information.