Intelligent Reflecting Surface-Assisted Wireless Key Generation for Low-Entropy Environments

TL;DR

This paper introduces a new IRS-assisted wireless key generation method that enhances randomness in static environments, demonstrating practical implementation with promising key rates and security features.

Contribution

It proposes a novel IRS-based architecture for physical-layer key generation, enabling secure keys in low-entropy static environments without special hardware.

Findings

Achieved a key generation rate of 97.39 bps.

Key disagreement rate of 6.5% after quantization.

Passed standard randomness tests.

Abstract

Physical layer key generation is a promising candidate for cryptographic key establishment between two wireless communication parties. It offers information-theoretic security and is an attractive alternative to public-key techniques. Here, the inherent randomness of wireless radio channels is used as a shared entropy source to generate cryptographic key material. However, practical implementations often suffer from static channel conditions which exhibit a limited amount of randomness. In the past, considerable research efforts have been made to address this fundamental limitation. However, current solutions are not generic or require dedicated hardware extensions such as reconfigurable antennas. In this paper, we propose a novel wireless key generation architecture based on randomized channel responses from an intelligent reflecting surface (IRS). Due to its passive nature, a cooperative IRS is well-suited to provide randomness for conventional resource-constrained radios. We conduct the first practical studies to successfully demonstrate IRS-based physical-layer key generation with an OFDM system. In a static environment, using a single subcarrier only, our IRS-assisted prototype system achieves a key generation rate (KGR) of 97.39 bps with 6.5% key disagreement rate (KDR) after quantization, while passing standard randomness tests.