Vehicular ad-hoc networks (VANETs) have envisioned various applications that substantially improve traffic safety and efficiency along the roads and highways. There are on-going projects both in academia and industry to standardize VANETs and to start off their real-life deployment. Despite the huge benefits envisioned by VANETs, they cannot be readily deployed as they are subjects of serious security and privacy concerns. These security and privacy concerns should be addressed and thus VANETs require a sound Identity management architecture before their anticipated deployment. Current research efforts on Identity management (IdM) in VANETs focus on employing Public Key Infrastructure (PKI) schemes to offer the well-known security and privacy requirements for VANETs. However, identity management is a far broader concept than offering security and privacy requirements.This thesis proposed a novel Identity management (IdM) architecture for VANETs that makes distinction between identity of the driver and the identity of the vehicle. To the best of our knowledge, our architecture is the first one to make such a distinction. Smartphones are used for establishing the identity of the driver while the IP Multimedia Subsystem (IMS) is used as an identity provider by establishing an OpenID provider within IMS. To preserve anonymity of users and to avoid location tracking, we tweaked OpenID so that it assigns different pseudonym OpenID identifiers for each user. Finally, we showed how our architecture can be used to realize interoperability across different VANET domains even in the absence of trust relationship among them.