Vehicular Ad hoc Network could manage the various critical issues of road transport. That is why it is the most crucial field of research for most of the researchers. This survey paper discusses various issues related to Security Challenges, Security Architecture actors, Security Authentication, Application Constraints, various trust models etc. this paper encourages you to think about various fields of work need to be carried out in this field for the better VANET environment. Various schemes have been mentioned which could be improved further as per considering various real time conditions.