A Survey of Security Services, Attacks, and Applications for Vehicular Ad Hoc Networks (VANETs) <s> Public Key Infrastructure Certificate Schemes <s> Vehicular networks are likely to become the most relevant form of mobile ad hoc networks. In this paper, we address the security of these networks. We provide a detailed threat analysis and devise an appropriate security architecture. We also describe some major design decisions still to be made, which in some cases have more than mere technical implications. We provide a set of security protocols, we show that they protect privacy and we analyze their robustness, and we carry out a quantitative assessment of the proposed solution. <s> BIB001 </s> A Survey of Security Services, Attacks, and Applications for Vehicular Ad Hoc Networks (VANETs) <s> Public Key Infrastructure Certificate Schemes <s> Conventional PKI is the most effective and efficient solution to non-repudiation. But, it also puts user privacy in danger because the user’s activities could be tracked via the unique public-key and certificate he presents in multiple transactions. Pseudonymous PKI (PPKI) solution achieves non-repudiation as well as privacy protection at the same time by providing Pseudonymous Public-Key (PPK) and Pseudonymous Certificate (PCert) that are computed by the user without CA intervention. PPK is as effective as conventional public-key in terms of non-repudiation. Furthermore, the PPKI solution is very efficient in terms of the size of PPK and PCert, and is scalable in terms of certification authority overhead. Therefore PPKI is particularly suitable for ubiquitous computing environments where authenticity, non-repudiation, privacy protection, efficiency, and scalability are key requirements. <s> BIB002 </s> A Survey of Security Services, Attacks, and Applications for Vehicular Ad Hoc Networks (VANETs) <s> Public Key Infrastructure Certificate Schemes <s> Effective and robust operations, as well as security and privacy are critical for the deployment of vehicular ad hoc networks (VANETs). Efficient and easy-to-manage security and privacy-enhancing mechanisms are essential for the wide-spread adoption of the VANET technology. In this paper, we are concerned with this problem; and in particular, how to achieve efficient and robust pseudonym-based authentication. We design mechanisms that reduce the security overhead for safety beaconing, and retain robustness for transportation safety, even in adverse network settings. Moreover, we show how to enhance the availability and usability of privacy-enhancing VANET mechanisms: Our proposal enables vehicle on-board units to generate their own pseudonyms, without affecting the system security. <s> BIB003 </s> A Survey of Security Services, Attacks, and Applications for Vehicular Ad Hoc Networks (VANETs) <s> Public Key Infrastructure Certificate Schemes <s> Security and especially privacy is an important requirement for the success of vehicular ad hoc networks (VANETs) in the future. To introduce and realize privacy a common method is to use pseudonyms to improve the unlinkability of nodes, events, and locations. Each node will own a multitude of pseudonyms and has to change them once in a while. The mobility of nodes has an important impact on the use and the change mechanism of pseudonyms in VANETs. This influence is analyzed by means of simulation and mathematical analysis. To have a simple yet solid mobility model the Manhatten grid mobility model was designed to model vehicle mobility. Using this model the two important parameters node re-interaction, how often and in what time intervals do nodes re-interact, and node quiet-time, how long should a node stay quiet before changing its pseudonym, are examined using simulation. In addition, an analytical method for determining the upper bound of the node quiet-time is presented. These results can mainly help to set parameters for pseudonym change protocols and estimate the impact of using these concepts in VANETs. <s> BIB004 </s> A Survey of Security Services, Attacks, and Applications for Vehicular Ad Hoc Networks (VANETs) <s> Public Key Infrastructure Certificate Schemes <s> Privacy is an important requirement in vehicle networks, because vehicles broadcast detailed location information. Also of importance is accountability due to safety critical applications. Conditional pseudonymity, i.e., usage of resolvable pseudonyms, is a common approach to address both. Often, resolvability of pseudonyms is achieved by authorities maintaining pseudonym- identity mappings. However, these mappings are privacy sensitive and require strong protection to prevent abuse or leakage. We present a new approach that does not rely on pseudonym-identity mappings to be stored by any party. Resolution information is directly embedded in pseudonyms and can only be accessed when multiple authorities cooperate. Our privacy-preserving pseudonym issuance protocol ensures that pseudonyms contain valid resolution information but prevents issuing authorities from creating pseudonym-identity mappings. <s> BIB005 </s> A Survey of Security Services, Attacks, and Applications for Vehicular Ad Hoc Networks (VANETs) <s> Public Key Infrastructure Certificate Schemes <s> PKI-based security in Vehicular Networks has to heavily rely on revoking the malicious user by adding his certificates to a Certificate Revocation List and broadcasting it to all the nodes. In a vehicular network with minimal infrastructure there is a need for a quick and reliable delivery or this CRL to all the nodes. While vehicle-to-vehicle or infrastructure-to-vehicle flooding could seem a natural way to deliver the CRL to all the nodes, existing flooding techniques either are unreliable, generate overwhelming unnecessary retransmission or incur excessive network control overhead. In this paper we study the problem of efficient distribution of CRLs in a vehicular network with minimal infrastructure by analyzing the performance of several broadcast protocols for CRL distribution. Our overall result is the definition and analysis of efficient CRL geo-cast protocols over vehicular networks with realistic scenarios of maps with varying density regions. Previous results did not consider the case of varying density regions or required a significant number of infrastructure servers. In the process, we reduce the problem of efficient geo-cast over a practical geographic map to the much more tractable problem of efficient broadcast over a region with an arbitrary vehicle density, which is solved via natural variants of known broadcasting protocols. <s> BIB006 </s> A Survey of Security Services, Attacks, and Applications for Vehicular Ad Hoc Networks (VANETs) <s> Public Key Infrastructure Certificate Schemes <s> In this paper, the primary objective is to discuss the details of scalable methods for distributing certificate revocation lists and other large files using vehicle-to-vehicle and vehicle-to-infrastructure communications while taking advantage of the multi-channel operations in IEEE 1609.4. We also discuss the results from a simulation study using the ns-3 network simulator to closely replicate the WAVE environment discussed in the IEEE 802.11p and 1609 draft standards. Realistic vehicle traces were used in the simulation study. The results show that the methods developed in this research scale very well for increasing vehicle densities. <s> BIB007 </s> A Survey of Security Services, Attacks, and Applications for Vehicular Ad Hoc Networks (VANETs) <s> Public Key Infrastructure Certificate Schemes <s> As a prime target of the quality of privacy in vehicular ad hoc networks (VANETs), location privacy is imperative for VANETs to fully flourish. Although frequent pseudonym changing provides a promising solution for location privacy in VANETs, if the pseudonyms are changed in an improper time or location, such a solution may become invalid. To cope with the issue, in this paper, we present an effective pseudonym changing at social spots (PCS) strategy to achieve the provable location privacy. In particular, we first introduce the social spots where several vehicles may gather, e.g., a road intersection when the traffic light turns red or a free parking lot near a shopping mall. By taking the anonymity set size as the location privacy metric, we then develop two anonymity set analytic models to quantitatively investigate the location privacy that is achieved by the PCS strategy. In addition, we use game-theoretic techniques to prove the feasibility of the PCS strategy in practice. Extensive performance evaluations are conducted to demonstrate that better location privacy can be achieved when a vehicle changes its pseudonyms at some highly social spots and that the proposed PCS strategy can assist vehicles to intelligently change their pseudonyms at the right moment and place. <s> BIB008 </s> A Survey of Security Services, Attacks, and Applications for Vehicular Ad Hoc Networks (VANETs) <s> Public Key Infrastructure Certificate Schemes <s> Abstract A vehicular Ad Hoc Network (VANET) is a class of mobile ad hoc network (MANET) which supports, vehicle to vehicle (V2V) and vehicle to infrastructure (V2I) communications. The significant features of VANET includes, self-organization, distributed networking, and highly dynamic topology. The VANET features and its applications to road safety have attracted a lot of interest in industry and academia more so into the research on improvement of transportation systems for saving millions of lives. The transmission of messages in open-access environment like VANET leads to the most critical and challenging security issues. Authentication, data confidentiality, data integrity, data availability, and non-repudiation are crucial components of security in VANET. This paper focuses on the authentication schemes in VANET as it plays a important role in secured communication. The authentication schemes are basically classified into three categories: cryptography techniques, digital signatures, and message verification techniques. The main objective of this paper is to provide a taxonomy of authentication schemes, and discuss their mechanisms, advantages, disadvantages, performance and scope of research. Furthermore, the paper concludes with presentation of open security issues in VANET authentication. <s> BIB009 </s> A Survey of Security Services, Attacks, and Applications for Vehicular Ad Hoc Networks (VANETs) <s> Public Key Infrastructure Certificate Schemes <s> Providing an efficient anonymous authentication scheme in vehicular ad hoc networks (VANETs) with low computational cost is a challenging issue. Even though, there are some existing schemes to provide anonymous authentication, the existing schemes suffer from high computational cost in the certificate and the signature verification process, which leads to high message loss. Therefore, they fail to meet the necessity of verifying hundreds of messages per second in VANETs. In our scheme, we propose an efficient anonymous authentication scheme to avoid malicious vehicles entering into the VANET. In addition, the proposed scheme offers a conditional tracking mechanism to trace the vehicles or roadside units that abuse the VANET. As a result, our scheme revokes the privacy of misbehaving vehicles to provide conditional privacy in a computationally efficient way through which the VANET entities will be anonymous to each other until they are revoked from the VANET system. Moreover, the proposed scheme is implemented and the performance analysis shows that our scheme is computationally efficient with respect to the certificate and the signature verification process by keeping conditional privacy in VANETs. <s> BIB010 </s> A Survey of Security Services, Attacks, and Applications for Vehicular Ad Hoc Networks (VANETs) <s> Public Key Infrastructure Certificate Schemes <s> In the near future, it is envisioned that vehicular Ad hoc networks (VANETs) will be making use of long-distance communication techniques, such as cellular networks and Worldwide Interoperability for Microwave Access (WiMAX), to get instant Internet access for making the communication between vehicles and fixed road side infrastructure. Moreover, VANETs will also make use of short-distance communication methods, such as Dedicated Short-Range Communications (DSRC) and Wireless Fidelity (Wi-Fi) to perform short range communication between vehicles in an ad hoc manner. This Internet connection can provide facility to other vehicles to send traffic related messages, collisions, infotainment messages other useful safety alerts. In such a scenario, providing authentication between vehicle to infrastructure and vehicle to vehicle is a challenging task. In order to provide this facility, in this paper, we propose a computationally efficient privacy preserving anonymous authentication scheme based on the use of anonymous certificates and signatures for VANETs in making them an important component of Internet of Things (IoT) and the development of smart cities. Even though there are several existing schemes available to provide such anonymous authentication based on anonymous certificates and signatures in VANETs, the existing schemes suffer from high computational cost in the certificate revocation list (CRL) checking process and in the certificate and the signature verification process. Therefore, it is not possible to meet the requirement of verifying a large number of messages per second in VANETs which would lead to increased message loss. Hence, we use a computationally efficient anonymous mutual authentication scheme to validate the message source as well as to ensure the integrity of messages along with a conditional tracking mechanism to trace the real identity of misbehaving vehicles and revoke them from VANET in the case of dispute. In this paper, we also introduce an efficient anonymous batch authentication protocol to be used in IoT for Road Side Units (RSUs) to authenticate multiple vehicles simultaneously rather than one after the other such that the total authentication time can be dramatically reduced. This proposed scheme is implemented and the performance analysis shows that our scheme is more efficient in terms of certificate and signature verification cost, while preserving conditional privacy in VANETs. <s> BIB011 </s> A Survey of Security Services, Attacks, and Applications for Vehicular Ad Hoc Networks (VANETs) <s> Public Key Infrastructure Certificate Schemes <s> Vehicular ad hoc networks (VANETs) are becoming the most promising research topic in intelligent transportation systems, because they provide information to deliver comfort and safety to both drivers and passengers. However, unique characteristics of VANETs make security, privacy, and trust management challenging issues in VANETs’ design. This survey article starts with the necessary background of VANETs, followed by a brief treatment of main security services, which have been well studied in other fields. We then focus on an in-depth review of anonymous authentication schemes implemented by five pseudonymity mechanisms. Because of the predictable dynamics of vehicles, anonymity is necessary but not sufficient to thwart tracking an attack that aims at the drivers’ location profiles. Thus, several location privacy protection mechanisms based on pseudonymity are elaborated to further protect the vehicles’ privacy and guarantee the quality of location-based services simultaneously. We also give a comprehensive analysis on various trust management models in VANETs. Finally, considering that current and near-future applications in VANETs are evaluated by simulation, we give a much-needed update on the latest mobility and network simulators as well as the integrated simulation platforms. In sum, this paper is carefully positioned to avoid overlap with existing surveys by filling the gaps and reporting the latest advances in VANETs while keeping it self-explained. <s> BIB012
Most of the vehicles contain public or private key for pseudonymous communication. In order to achieve a secure and reliable way, the public key certificates are the best methods that are used in public key infrastructure (PKI) to authenticate vehicles. It contains the digital signature of the certification authority (CA) and vehicle key for authentication BIB012 . The CA is the centralized management unit, which is responsible to certify nodes, keys, etc. Furthermore, it can also authenticate the vehicles in V2V communication. Every vehicle needs to be register with the CA database before officially join the VANET system. The vehicle can communicate with CA in two ways either directly, such as offline registration or via RSU as an indirect online registration. Raya et al. BIB001 introduced a new method, which utilizes the anonymous public keys to provide privacy. The anonymous keys must be changed in the way that the receiver will not be able to track the vehicle owner key. The main demerits are that it required a large amount of storage and memory and also requires a huge amount of certificate revocation list (CRL) checks, since using a large number of anonymous keys. Therefore, it may be the reason for the DOS attack due to a large amount of computational overhead. Calandriello et al. BIB003 introduced a robust pseudonym-based authentication method to reduce the security overhead but keeps maintaining the robustness of traffic safety. This scheme alleviates the limitations of a pseudonym by using the combination of the baseline pseudonym and group signature, which can generate its own pseudonym on-the-fly and self-certification BIB009 . Additionally, it minimizes the requirements of handling the pseudonym in authentication. In Reference  , Wasef and Shen introduced an expedite message authentication protocol (EMAP) method, which adopts public key infrastructure (PKI) and certificate revocation lists (CRLs) for their security. In this scheme, EMAP for VANETs replaced the lengthy process of CRL by an effective revocation process. This process uses a keyed hash message authentication code (HMAC) in EMAP. The purpose of the key is used to calculate HMAC and is shared only among non-revoked OBUs to safely share and update the secret key. Due to the message verification delay, which resulted in a significantly reduced message loss ratio in EMAP, as compared with the conventional authentication. Reference BIB004 proposed a new scheme in which vehicles generate a request to CAs for short-term pseudonyms during specific intervals. To reduce the communication overhead with CAs, Reference BIB002 introduced the self-issuance scheme to enable the vehicle to generate pseudonyms independently. Rongxing et al. BIB008 introduced a new method for effective pseudonyms changing at the social spot (PCS) for privacy of location, by determining several vehicles gathered on specific spots such as an intersection or the parking area. It utilizes anonymity size as a privacy metric (ASS) and, if ASS reaches the threshold, then the pseudonyms are changed simultaneously. However, it cannot perform well in a low density. In the year 2010, Schuab et al. BIB005 proposed a new approach that does not depend on the pseudonyms-identity mapping to achieve accountability but instead, resolution information is embed with V-token pseudonym certificates. In this scheme, by using the V-token approach, each vehicle carries its own resolution information, which can provide a scalability advantage. The main challenge is the revocation of the pseudonym certificate, which may limit the scalability in the VANET. In case, if the vehicle long-term certificate is revoked, then the vehicle cannot obtain a new pseudonym from CAs. In recent years, few studies have been proposed on the CRLs' distribution methods BIB006 BIB007 . These methods are unable to stop the revoked vehicle from continuously communicating in VANETs until and unless all the pseudonyms become inactive. The drawbacks of checking the CRL process make it unreliable to authenticate a large number of messages under the specific period in VANETs BIB011 . Azees et al. BIB010 introduced an effective anonymous authentication with a conditional privacy (EAAP) scheme to avoid a malicious vehicle from entering in the VANETs. This scheme is used to track mechanism and track vehicles or RSUs that create disturbance to VANETs. Recently, bilinear pairing was introduced in which the TA in EAAP is not required to keep the anonymous certificate of the vehicles and RSUs  . Additionally, the TA has the right to cancel the anonymity of a disobedient vehicle and reveal their identity in a group. Then, the revoked identity added to the identity revocation list (IRL) was managed under the supervision of TA.