List decoding for arbitrarily varying wiretap channels

We consider a communication scenario in which the channel undergoes two different classes of attacks at the same time: a passive eavesdropper and an active jammer. This scenario is modeled by the concept of arbitrarily varying wiretap channels (AVWCs), in which the channel varies from one channel use to the other in an unknown and arbitrary manner. It has been shown that uncorrelated codes fail to establish reliable communication over the class of symmetrizable AVWCs. For this class more sophisticated coding techniques such as correlated random codes are needed. Correlated random codes are not easy to realize in practice because they require a sort of coordination between the transmitter and the receiver, which is not always possible. In this paper, we aim to resolve the ambiguity of symmetrizable AVWCs in the absence of coordination resources using list decoding. In particular, we show that for an AVWC where we allow for a non-vanishing decoding error probability, we can construct a list code whose rate is close to the correlated secrecy capacity. The list size needed by such code is shown to be finite and independent of the block length. Moreover, the constructed list code assures that the information leakage of the confidential message with respect to the strong secrecy criterion decays exponentially fast.