Wiretap Channels with Random States Non-Causally Available at the Encoder

TL;DR

This paper derives a new lower bound on the secrecy capacity of state-dependent wiretap channels with non-causal encoder side information, using a novel superposition coding scheme, and characterizes the capacity for certain channel classes.

Contribution

It introduces an improved lower bound on secrecy capacity and provides an exact capacity characterization for a specific class of state-dependent wiretap channels.

Findings

New lower bound on secrecy capacity derived.

Exact capacity characterized for a class of channels.

Results improve upon previous bounds by Prabhakaran et al.

Abstract

We study the state-dependent (SD) wiretap channel (WTC) with non-causal channel state information (CSI) at the encoder. This model subsumes all other instances of CSI availability as special cases, and calls for an efficient utilization of the state sequence for both reliability and security purposes. A lower bound on the secrecy-capacity, that improves upon the previously best known result published by Prabhakaran et al., is derived based on a novel superposition coding scheme. Our achievability gives rise to the exact secrecy-capacity characterization of a class of SD-WTCs that decompose into a product of two WTCs, where one is independent of the state and the other one depends only on the state. The results are derived under the strict semantic-security metric that requires negligible information leakage for all message distributions.