Comparison of Pseudonym Change Strategies for C-ITS

Privacy is very sensitive and is challenging over Cooperative Intelligent Transport Systems (C-ITS). In such systems, Vehicles broadcast messages containing private data as position and speed, etc,. This data may be linked to the driver's identity. Many intruders working for employers, insurance companies or criminal organizations, could track drivers and get private data sent by vehicles. Therefore, privacy protection solutions take profit of the use of multiple identities (denoted pseudonyms). In addition to getting various identities, senders have to authenticate all their messages. These messages should be signed using certificates. Then, a pseudonym is more than a simple identity, it is a pseudonym certificate which is denoted PC. A sa consequence, each vehicle has a set of PCs. Each PC is used for a limited period of time, it must be changed according to various rules. In this paper, we compare the performances of three different pseudonym change strategies which have been implemented and evaluated over. These strategies have been described in [1]–[3]. The first one has been experimented along various European projects (SCOOP@F, C-Roads, Intercor and Indid). The second one aims to reduces the number of PCs used in the system. When a certificate has been used by a vehicle, this PC will be swap with another driver PC. The third one is based on the idea that any trusted vehicle within the system is able to generate a valid certificat to any neighbor when they drive close to each other during a long period.