Two-Way Physical Layer Security Protocol for Gaussian Channels

TL;DR

This paper introduces a two-way physical layer security protocol for Gaussian channels that overcomes the limitations of traditional one-way protocols by eliminating the need for channel degradation, ensuring positive secrecy capacity.

Contribution

The paper proposes a novel two-way protocol for physical layer security in Gaussian channels that does not require channel degradation, unlike traditional one-way methods.

Findings

The two-way protocol always achieves positive secrecy capacity.

Numerical results demonstrate capacity gains over traditional methods.

Application to satellite channels shows practical relevance.

Abstract

In this paper we propose a two-way protocol of physical layer security using the method of privacy amplification against eavesdroppers. First we justify our proposed protocol by analyzing the physical layer security provided by the classic wiretap channel model (i.e. one-way protocol). In the Gaussian channels, the classic one-way protocol requires Eve's channel to be degraded w.r.t. Bob's channel. However, this channel degradation condition depends on Eve's location and whether Eve's receiving antenna is more powerful than Bob's. To overcome this limitation, we introduce a two-way protocol inspired in IEEE TIT (1993) that eliminates the channel degradation condition. In the proposed two-way protocol, on a first phase, via Gaussian channel, Bob sends randomness to Alice, which is partially leaked to Eve. Then, on a second phase, Alice transmits information to Bob over a public noiseless channel. We derive the secrecy capacity of the two-way protocol when the channel to Eve is also Gaussian. We show that the capacity of the two-way protocol is always positive. We present numerical values of the capacities illustrating the gains obtained by our proposed protocol. We apply our result to simple yet realistic models of satellite communication channels.