Vehicular Ad Hoc Networks (VANETs) is a type of Ad Hoc Networks in which mobile nodes are vehicles. VANET architecture consists of vehicles, Road Side Units (RSUs) and a Certificate Authority. RSUs are located at certain points on the road network similar to access points in wireless networks. Certificate Authority coordinates offering security services to the whole network scale. In VANETs, vehicles may communicate with each other Vehicle-to-Vehicle (V2V) mode, or with Infrastructure Vehicle-to-Infrastructure (V2I) mode. VANETs can provide safety, traffic related and entertainment applications. Exchanging safety (life-critical) messages requires message integrity, sender authentication and privacy for participants. In this paper, a comparison is held between Public key Schemes and Symmetric Key Schemes in supporting security for VANETs.