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

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. Index Terms two-way wiretap channel, secrecy capacity, feedback, achievable secrecy rate region, one-sided secrecy