— As there is a substantial increase in the automation industry, Security is the major concern among the vehicles. Software and hardware are combined to provide better drivability and comfort in vehicles. Information such as safety and nonsafety are interchanged among the vehicles through messages in an intelligent transport system. VANET an intelligent transportation system plays a vital role in enhancing the security and safety of passengers as well as drivers by equipping the vehicle with RSU (Road Side Unit) and OBU (On-Board Unit). Production of an extensive amount of data in VANET communication needs an intelligent storage system. For this Fog Computing has a vital role in the storage and computation of data. In this paper, we present a study on various authentication attacks, authentication protocols and their mechanism. Open issues, Future scope of VANET using Fog, Survey on authentication protocols in VANET using fog computing are discussed. Taxonomy of authentication attacks with their summary and insights are presented.