Randomized Certificate Replacement with Bounded Collateral Damage

Abstract

To accomplish secure communication in vehicular networks, public key infrastructure (PKI) can be employed. However, traditional PKI systems are not suitable because a unique certificate is assigned to each vehicle and thus no anonymity is guaranteed. In the combinatorial certificate schemes, each vehicle is assigned multiple certificates from a shared certificate pool and each certificate in the pool is assigned to multiple vehicles to achieve a level of anonymity. When a certificate assigned to a misbehaving vehicle is revoked, a certificate replacement procedure is executed to all vehicles sharing the certificate. To replace the revoked certificate, a randomized certificate replacement scheme probabilistically assigns different certificates to different vehicles, which can reduce collateral damage caused by repeatedly misusing a certificate and its replacement certificates. Unfortunately, previous randomized certificate replacement schemes allow unbounded collateral damage; a finite number of certificate replacements cannot detect the misbehaving vehicle with certainty. To address this problem, we propose a new randomized certificate replacement scheme with bounded collateral damage.