Authentication assures that the messages are received from genuine nodes. Thus, authentication plays a significant role in VANET security enhancement. The authentication is performed in two ways that are node level and message level. The node-level authentication verifies the legitimate level of network nodes. The message level authentication verifies the integrity level of the received messages. The authentication gives strong security against manipulation and data integrity attacks. The authentication strategies are mainly classified under three categories that are cryptography methods, message verification strategies, and digital signature schemes. The cryptography methods exploit various public-private key pairs for authentication, and the digital signature models use different types of signatures for verification.