A Survey of Security Services, Attacks, and Applications for Vehicular Ad Hoc Networks (VANETs) <s> Research Work on Data Integrity <s> We propose a novel group signature based security framework for vehicular communications. Compared to the traditional digital signature scheme, the new scheme achieves authenticity, data integrity, anonymity, and accountability at the same time. Furthermore, we describe a scalable role-based access control approach for vehicular networks. Finally, we present a probabilistic signature verification scheme that can efficiently detect the tampered messages or the messages from an unauthorized node. <s> BIB001 </s> A Survey of Security Services, Attacks, and Applications for Vehicular Ad Hoc Networks (VANETs) <s> Research Work on Data Integrity <s> In this paper, we first identify some unique design requirements in the aspects of security and privacy preservation for communications between different communication devices in vehicular ad hoc networks. We then propose a secure and privacy-preserving protocol based on group signature and identity (ID)-based signature techniques. We demonstrate that the proposed protocol cannot only guarantee the requirements of security and privacy but can also provide the desired traceability of each vehicle in the case where the ID of the message sender has to be revealed by the authority for any dispute event. Extensive simulation is conducted to verify the efficiency, effectiveness, and applicability of the proposed protocol in various application scenarios under different road systems. <s> BIB002 </s> A Survey of Security Services, Attacks, and Applications for Vehicular Ad Hoc Networks (VANETs) <s> Research Work on Data Integrity <s> Receiver-location privacy is an important security requirement in privacy-preserving Vehicular Ad hoc Networks (VANETs), yet the unavailable receiver's location information makes many existing packet forwarding protocols inefficient in VANETs. To tackle this challenging issue, in this paper, we propose an efficient social-tier-assisted packet forwarding protocol, called STAP, for achieving receiver-location privacy preservation in VANETs. Specifically, by observing the phenomena that vehicles often visit some social spots, such as well-traversed shopping malls and busy intersections in a city environment, we deploy storage-rich Roadside Units (RSUs) at social spots and form a virtual social tier with them. Then, without knowing the receiver's exact location information, a packet can be first forwarded and disseminated in the social tier. Later, once the receiver visits one of social spots, it can successfully receive the packet. Detailed security analysis shows that the proposed STAP protocol can protect the receiver's location privacy against an active global adversary, and achieve vehicle's conditional privacy preservation as well. In addition, performance evaluation via extensive simulations demonstrates its efficiency in terms of high delivery ratio and low average delay. <s> BIB003
To protect the integrity of the sending message, digital signatures are generated and attached to the messages BIB001 . In recent years, few studies indicate the accurate and reliable information for preserving data integrity in the VANET system. This section will explain the existing methods for data integrity in the VANETs. The main problem occurs when an inaccessible receiving location generates many current packets and forwarding protocols inefficiently in VANETs. To solve this problem, Reference BIB003 introduced a STAP approach to acquire the receiver's location privacy preservation in VANETs. By using the concept vehicles, always travel to the busy places and downtown area such as the shopping mall, busy street, etc. In order to achieve data integrity, they deploy RSUs at the main social spot to form a social tier with them. First, the sender computes message authentication code (MAC) and attaches the generated code to the message before sending to the receiver. Once the message is received, in order to obtain integrity, the receiver uses the key session to check MAC. This method is limited to only the busiest place and, due to traffic congestion, this algorithm may consume large memory. Lin and Li  introduced an efficient cooperative authentication technique for the VANETs system. This technique is used to shorten the authentication overhead on individual vehicles and to reduce the delay. To block the various attacks, this method uses a token method to control and manage the authentication workload. When the vehicle passes the RSUs, the vehicle can get the evidence token from trusted authority (TA). Therefore, this token indicates that the vehicle contributed in cooperative authentication before. This method comprises of the large computational algorithm to control the authentication issue. Lin et al. BIB002 introduced a group signature and identity-based signature (GSIS) method, which is used to develop secure privacy preserving the protocol based on the group signature and identity-based signature schemes. In case of a dispute, the proposed method protocol can also be used to trace each vehicle, but ID of the sending message need to be disclosed by TA.