Evaluating on-demand pseudonym acquisition policies in vehicular communication systems

Abstract

Standardization and harmonization efforts have reached a consensus towards using a special-purpose Vehicular Public-Key Infrastructure (VPKI) in upcoming Vehicular Communication (VC) systems. However, there are still several technical challenges with no conclusive answers; one such an important yet open challenge is the acquisition of shortterm credentials, pseudonym: how should each vehicle interact with the VPKI, e.g., how frequently and for how long? Should each vehicle itself determine the pseudonym lifetime? Answering these questions is far from trivial. Each choice can affect both the user privacy and the system performance and possibly, as a result, its security. In this paper, we make a novel systematic effort to address this multifaceted question. We craft three generally applicable policies and experimentally evaluate the VPKI system performance, leveraging two large-scale mobility datasets. We consider the most promising, in terms of efficiency, pseudonym acquisition policies; we find that within this class of policies, the most promising policy in terms of privacy protection can be supported with moderate overhead. Moreover, in all cases, this work is the first to provide tangible evidence that the state-of-the-art VPKI can serve sizable areas or domain with modest computing resources.

Scalable & Resilient Vehicle-Centric Certificate Revocation List Distribution in Vehicular Communication Systems

“…Preliminary assumptions: We leverage a state-of-the-art VPKI system [43], [54], [55] that provides pseudonyms in an on-demand fashion: each vehicle ''decides'' when to trigger the pseudonym acquisition process based on various factors [56], [57]. Such a scheme requires sparse connectivity to the VPKI, but it facilitates an OBU to be preloaded with pseudonyms proactively, covering a longer period, e.g., a week or a month, should the connectivity be expected heavily intermittent.…”

“…Such a scheme requires sparse connectivity to the VPKI, but it facilitates an OBU to be preloaded with pseudonyms proactively, covering a longer period, e.g., a week or a month, should the connectivity be expected heavily intermittent. The efficiency, scalability and robustness of the VPKI system is systematically investigated [43], [54], [55], [56] with the VPKI handles a large workload. Moreover, it enhances user privacy, notably preventing linking pseudonyms based on timing information [38] (the instance of issuance and the pseudonym lifetime) as well as offers strong user privacy protection even in the presence of honest-but-curious VPKI entities.…”

Scaling pseudonymous authentication for large mobile systems

“…Each vehicle "decides" when to trigger the pseudonym acquisition process based on various factors [55]. Such a scheme requires sparse connectivity to the VPKI, but it facilitates an On-Board Unit (OBU) to be preloaded with pseudonyms proactively, covering a longer period, e.g., a week or a month, should the connectivity be expected heavily intermittent.…”

“…Pseudonym Acquisition Process (Protocol 1). Each vehicle first requests an anonymous ticket [54,55] from its H-LTCA, using it to interact with the desired PCA to obtain pseudonyms; due to lack of space, we provide the detailed ticket acquisition process in Appendix. Upon reception of a valid ticket, it generates Certificate Signing Requests (CSRs) with Elliptic Curve Digital Signature Algorithm (ECDSA) public/private key pairs [45,51] and 6 A dummy ticket request is constructed by an LTCA Pod to validate the correctness of ticket issuance procedure while a dummy pseudonym request is constructed by a PCA Pod to ensure the correctness of pseudonym issuance procedure.…”

“…For example, leveraging anonymous authentication schemes for the majority of vehicles results in causing 30% increase in cryptographic processing overhead in order to validate CAMs [56]. Thus, it is crucial to provide a highly-available, scalable, and resilient VPKI design that could efficiently issue pseudonyms in an on-demand fashion 2 [55,65].…”