Discrete Memoryless Interference and Broadcast Channels with Confidential Messages: Secrecy Rate Regions

TL;DR

This paper investigates the secrecy capacity regions of discrete memoryless interference and broadcast channels with confidential messages, providing bounds, coding schemes, and specific results for Gaussian channels with artificial noise strategies.

Contribution

It introduces new inner and outer bounds for secrecy capacity regions, including a double-binning coding scheme and power allocation strategies for Gaussian channels.

Findings

Outer bounds have identical mutual information expressions for both channels.

Double-binning coding scheme achieves inner bounds while preserving confidentiality.

Artificial noise power allocation outperforms traditional methods in Gaussian channels.

Abstract

We study information-theoretic security for discrete memoryless interference and broadcast channels with independent confidential messages sent to two receivers. Confidential messages are transmitted to their respective receivers with information-theoretic secrecy. That is, each receiver is kept in total ignorance with respect to the message intended for the other receiver. The secrecy level is measured by the equivocation rate at the eavesdropping receiver. In this paper, we present inner and outer bounds on secrecy capacity regions for these two communication systems. The derived outer bounds have an identical mutual information expression that applies to both channel models. The difference is in the input distributions over which the expression is optimized. The inner bound rate regions are achieved by random binning techniques. For the broadcast channel, a double-binning coding scheme allows for both joint encoding and preserving of confidentiality. Furthermore, we show that, for a special case of the interference channel, referred to as the switch channel, the two bound bounds meet. Finally, we describe several transmission schemes for Gaussian interference channels and derive their achievable rate regions while ensuring mutual information-theoretic secrecy. An encoding scheme in which transmitters dedicate some of their power to create artificial noise is proposed and shown to outperform both time-sharing and simple multiplexed transmission of the confidential messages.