Effects of Feedback on the One-sided Secrecy of Two-way Wiretap through Multiple Transmissions

TL;DR

This paper investigates the one-sided secrecy of two-way wiretap channels with feedback over multiple transmissions, deriving achievable secrecy rates, outer bounds, and demonstrating feedback's benefits in enhancing secrecy capacity.

Contribution

It introduces the first achievable secrecy rate region for two-way wiretap channels with feedback under one-sided secrecy and characterizes feedback's role in improving secrecy capacity.

Findings

Secrecy capacity regions are established for XOR channels.

Feedback enlarges the achievable secrecy rate region.

Inner and outer bounds are closely explored for binary input channels.

Abstract

In this paper, the one-sided secrecy of two-way wiretap channel with feedback is investigated, where the confidential messages of one user through multiple transmissions is guaranteed secure against an external eavesdropper. For one thing, one-sided secrecy satisfies the secure demand of many practical scenarios. For another, the secrecy is measured over many blocks since the correlation between eavesdropper's observation and the confidential messages in successive blocks, instead of secrecy measurement of one block in previous works. Thus, firstly, an achievable secrecy rate region is derived for the general two-way wiretap channel with feedback through multiple transmissions under one-sided secrecy. Secondly, outer bounds on the secrecy capacity region are also obtained. The gap between inner and outer bounds on the secrecy capacity region is explored via the binary input two-way wiretap channels. Most notably, the secrecy capacity regions are established for the XOR channel. Furthermore, the result shows that the achievable rate region with feedback is larger than that without feedback. Therefore, the benefit role of feedback is precisely characterized for two-way wiretap channel with feedback under one-sided secrecy.