Vehicular ad hoc network has caught much attention from researchers in industry and academia. Security is one of the main issues that must be addressed for successful deployment of VANETs. Many researchers have proposed security protocols and frameworks. Since no standards have been finalized as yet, much of the early research works regarding security has become obsolete. Efficiency and reliability are two of the core issues that need to be resolved. In this paper a security framework is proposed for efficient periodic and event-driven messages. Proposed framework uses TPM hardware to reduce processing time for secure messaging. Framework is based upon two major components i.e. smart utilization of symmetric and asymmetric security methods and a trusted grouping scheme. Furthermore, simulations were carried out to highlight the potential bottlenecks created by processing delays while using trial security standard for VANET. © 2011 Springer-Verlag.