RHyTHM: A Randomized Hybrid Scheme To Hide in the Mobile Crowd

TL;DR

RHyTHM is a scheme that allows vehicles to maintain privacy and operational status during connectivity outages by collaboratively generating and sharing pseudonyms, balancing privacy and computational efficiency.

Contribution

The paper introduces RHyTHM, a novel randomized hybrid scheme enabling vehicles to preserve privacy and functionality during connectivity disruptions without significant overhead.

Findings

RHyTHM effectively enhances vehicle privacy during disconnections.

The scheme maintains operational pseudonym use with manageable computational costs.

Experimental results demonstrate improved privacy preservation in simulated scenarios.

Abstract

Any on-demand pseudonym acquisition strategy is problematic should the connectivity to the credential management infrastructure be intermittent. If a vehicle runs out of pseudonyms with no connectivity to refill its pseudonym pool, one solution is the on-the-fly generation of pseudonyms, e.g., leveraging anonymous authentication. However, such a vehicle would stand out in the crowd: one can simply distinguish pseudonyms, thus signed messages, based on the pseudonym issuer signature, link them and track the vehicle. To address this challenge, we propose a randomized hybrid scheme, RHyTHM, to enable vehicles to remain operational when disconnected without compromising privacy: vehicles with valid pseudonyms help others to enhance their privacy by randomly joining them in using on-the-fly self-certified pseudonyms along with aligned lifetimes. This way, the privacy of disconnected users is enhanced with a reasonable computational overhead.