PSRAKA: Physically Secure and Robust Authenticated Key Agreement for VANETs

Authenticated key agreement (AKA) allows vehicles and road side units (RSUs) to mutually authenticate and establish shared session keys, which can be implemented to secure vehicular ad-hoc networks (VANETs). However, most of existing relative schemes fail to support physical security and tracing robustness, and lack a mechanism to balance pseudonym unlinkability and system efficiency. In this paper, we propose PSRAKA, a physically secure and robust authenticated key agreement scheme for VANETs, which enables anonymous authentication on vehicles through chameleon hash functions. In particular, physical security is guaranteed by integrating physical unclonable functions and fuzzy extractors to resist against physical capture attacks. Our scheme is the first to support robustness by allowing the vehicle and central authority to jointly sign or commit to the vehicle's real identity, chameleon hash value and public key for binding to ensure public verification and prevent malicious accusations during tracing. Meanwhile, it is the first to model the relationship of vehicle pseudonym unlinkability and system efficiency for balance by formulating the unlinkability based on the frequency of pseudonym updates. PSRAKA achieves anonymity, conditional privacy, robustness, key escrow freeness and physical security, and resists against most known attacks. Comprehensive performance analysis and evaluation suggest the potential usability of PSRAKA.