Fast and Secure Key Generation with Channel Obfuscation in Slowly Varying Environments

TL;DR

This paper introduces a novel physical-layer key generation method using channel obfuscation, significantly increasing the rate and security of cryptographic keys in slowly varying wireless environments.

Contribution

It proposes a new channel obfuscation technique with random filtering and antenna scheduling, enhancing key generation speed and security over existing methods.

Findings

Achieves about 67 bits per packet in key generation.

Produces keys that pass NIST randomness tests.

Outperforms existing approaches in slow-varying environments.

Abstract

The physical-layer secret key generation has emerged as a promising solution for establishing cryptographic keys by leveraging reciprocal and time-varying wireless channels. However, existing approaches suffer from low key generation rates and vulnerabilities under various attacks in slowly varying environments. We propose a new physical-layer secret key generation approach with channel obfuscation, which improves the dynamic property of channel parameters based on random filtering and random antenna scheduling. Our approach makes one party obfuscate the channel to allow the legitimate party to obtain similar dynamic channel parameters yet prevents a third party from inferring the obfuscation information. Our approach allows more random bits to be extracted from the obfuscated channel parameters by a joint design of the K-L transform and adaptive quantization. A testbed implementation shows that our approach, compared to the existing ones that we evaluate, performs the best in generating high entropy bits at a fast rate and a high-security level in slowly varying environments. Specifically, our approach can achieve a significantly faster secret bit generation rate at about $67$ bit/pkt, and the key sequences can pass the randomness tests of the NIST test suite.