Using query frequencies in tree-based revocation for certificateless authentication in VANETs

Revocation of dishonest users is not an easy problem. This paper proposes a new way to manage revocation of pseudonyms in vehicular ad-hoc networks when using identity-based authentication to increase efficiency and security through certificateless authentication. In order to improve the performance of revocation lists, this paper proposes the use of a data structure based on authenticated dynamic hash k-ary trees and the frequency with which revoked pseudonyms are consulted. The use of the knowledge about the frequency of consultation of revoked pseudonyms allows an easier access to the most popular revoked pseudonyms to the detriment of revoked pseudonyms that are the least consulted. Accordingly, the proposal is especially useful in urban environments where there are vehicles that spend more time on road than others, such as public service vehicles.