LIAP: A local identity-based anonymous message authentication protocol in VANETs

In vehicular ad hoc networks (VANETs), vehicle communicates with other nodes through an open wireless channel, which raises many potential safety issues. Both the public key infrastructure (PKI) and identity based authentication protocols can meet the requirements of security and privacy of VANETs. However, the receiver needs to check certificate revocation list (CRL) before certificate and signature verification in PKI-base schemes. The additional CRL checking reduces the authentication efficiency. In the identity-based schemes, every vehicle holds too many valid identities in order to protect privacy. It is complicated to revoke the membership of vehicle. To cope with the inherent issues, we propose a local identity-based anonymous message authentication protocol (LIAP) for VANETs, in which each vehicle and road side unit (RSU) is assigned a unique long term certification from the certificate authority (CA) in registration phase. RSU is in charge of managing and assigning the local master keys to every vehicle of entering its communication range. When vehicle meets a new RSU, they authenticate each other by their long certificates. The valid vehicle can obtain the local master keys from current RSU to generate the localized anonymous identity. To protect privacy, vehicle randomly chooses the anonymous identity to sign the safety-related message, which can be efficiently verified by the single or batch authentication manner. Finally, performance analysis and simulation show that LIAP is effective in terms of authentication speed and communication overhead.