Interference-Assisted Secret Communication

TL;DR

This paper demonstrates how wireless interference can be strategically used to enhance secrecy by confusing eavesdroppers while allowing intended receivers to decode confidential messages, leveraging the superposition property of wireless signals.

Contribution

It introduces a new model with an interferer aiding secrecy in wireless channels and provides achievable secrecy rates for this setup.

Findings

Interference can be exploited to improve wireless secrecy.

The interferer can send signals decodable by the receiver but not by the eavesdropper.

Secrecy is enhanced when the interferer has a better channel to the receiver than to the eavesdropper.

Abstract

Wireless communication is susceptible to adversarial eavesdropping due to the broadcast nature of the wireless medium. In this paper it is shown how eavesdropping can be alleviated by exploiting the superposition property of the wireless medium. A wiretap channel with a helping interferer (WT-HI), in which a transmitter sends a confidential message to its intended receiver in the presence of a passive eavesdropper, and with the help of an independent interferer, is considered. The interferer, which does not know the confidential message, helps in ensuring the secrecy of the message by sending independent signals. An achievable secrecy rate for the WT-HI is given. The results show that interference can be exploited to assist secrecy in wireless communications. An important example of the Gaussian case, in which the interferer has a better channel to the intended receiver than to the eavesdropper, is considered. In this situation, the interferer can send a (random) codeword at a rate that ensures that it can be decoded and subtracted from the received signal by the intended receiver but cannot be decoded by the eavesdropper. Hence, only the eavesdropper is interfered with and the secrecy level of the confidential message is increased.