Perfectly Secure Key Agreement Over a Full Duplex Wireless Channel

TL;DR

This paper introduces a novel full duplex wireless channel-based secret key agreement method that leverages channel reciprocity and a bisparse blind deconvolution scheme, achieving perfect security without channel probing.

Contribution

The paper presents a new security primitive for WPAN that relies on channel reciprocity and full duplex communication, avoiding dependence on channel entropy.

Findings

Proves correctness and perfect security of the bisparse blind deconvolution scheme.

Provides a lower bound on secret key bits extractable from the channel.

Validates the approach through experimental verification.

Abstract

Secret key generation (SKG) between authenticated devices is a pivotal task for secure communications. Diffie-Hellman (DH) is de-facto standard but not post-quantum secure. In this paper, we shall invent and analyze a new security primitive that is specifically designed for WPAN. For WPAN, wireless channel-based SKG has been proposed but was not widely deployed due to its critical dependence on the channel's entropy which is uncontrollable. We formulate a different approach: We still exploit channel properties but mainly hinge on the reciprocity of the wireless channel and not on the channel's entropy. The radio advantage comes from the use of full duplex communication. We show that in this situation both legitimate parties can agree on a common secret key even without ever probing the channel at all. At the core is a new bisparse blind deconvolution scheme for which we prove correctness and information-theoretic, i.e. perfect, security. We show that, ultimately, a secret key can be extracted and give a lower bound for the number of secret key bits which is then verified by experiments.