Security Models in Vehicular Ad-hoc Networks: A Survey
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paper_title: Overview of security issues in Vehicular Ad-hoc Networks

paper_content:

Vehicular ad-hoc networks (VANETs) are a promising communication scenario. Several new applications are envisioned, which will improve traffic management and safety. Nevertheless, those applications have stringent security requirements, as they affect road traffic safety. Moreover, VANETs face several security threats. As VANETs present some unique features (e.g. high mobility of nodes, geographic extension, etc.) traditional security mechanisms are not always suitable. Because of that, a plethora of research contributions have been presented so far. This chapter aims to describe and analyze the most representative VANET security developments.
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paper_title: Privacy Protection Through k.anonymity in Location.based Services

paper_content:

AbstractThe advent of Location-based Services (LBS), especially in wireless communications systems, has raised a growing concern for user about his privacy. As for every location-based query, the user has to reveal his location coordinates (through technologies like Global Positioning Systems); if this information could be revealed to anybody, it becomes a privacy breach. To take care of these issues, several techniques have come up among which k-anonymity has been most widely used and studied in different forms and different contexts. In this paper, we have reviewed the application of k-anonymity for LBS and its recent advancements. While doing so, we have recognized three perspectives for the applicability of k-anonymity for LBS: the application of k-anonymity based on the architecture, based on the algorithms for anonymization, and based on the types of k-anonymity (according to the different query processing techniques). Hence, the review has been done within the framework of these perspectives. These...
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paper_title: An Efficient Anonymous Authentication Protocol for Secure Vehicular Communications

paper_content:

As vehicular communications bring the promise of improved road safety and optimized road traffic through cooperative systems applications, it becomes a prerequisite to make vehicular communications secure for the successful deployment of vehicular ad hoc networks. In this paper, we propose an efficient authentication protocol with anonymous public key certificates for secure vehicular communications. The proposed protocol follows a system model to issue on-the-fly anonymous public key certificates to vehicles by road-side units. In order to design an efficient authentication protocol, we consider a key-insulated signature scheme for certifying anonymous public keys of vehicles to the system model. We demonstrate experimental results to confirm that the proposed protocol has better performance than other protocols based on group signature schemes.
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paper_title: Security in automotive bus systems

paper_content:

This work presents a study of current and future bus systems with respect to their security against various malicious attacks. After a brief description of the most well-known and established vehicular communication systems, we present feasible attacks and potential exposures for these automotive networks. We also provide an approach for secured automotive communication based on modern cryptographic mechanisms that provide secrecy, manipulation prevention and authentication to solve most of the vehicular bus security issues.
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paper_title: ASPE: attribute-based secure policy enforcement in vehicular ad hoc networks

paper_content:

Vehicular ad hoc networks (VANETs) are usually operated among vehicles moving at high speeds, and thus their communication relations can be changed frequently. In such a highly dynamic environment, establishing trust among vehicles is difficult. To solve this problem, we propose a flexible, secure and decentralized attribute based secure key management framework for VANETs. Our solution is based on attribute based encryption (ABE) to construct an attribute based security policy enforcement (ASPE) framework. ASPE considers various road situations as attributes. These attributes are used as encryption keys to secure the transmitted data. ASPE is flexible in that it can dynamically change encryption keys depending on the VANET situations. At the same time, ASPE naturally incorporates data access control policies on the transmitted data. ASPE provides an integrated solution to involve data access control, key management, security policy enforcement, and secure group formation in highly dynamic vehicular communication environments. Our performance evaluations show that ASPE is efficient and it can handle large amount of data encryption/decryption flows in VANETs.
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paper_title: Secure Vehicular Communication Systems: Design and Architecture

paper_content:

Significant developments have taken place over the past few years in the area of vehicular communication systems. Now, it is well understood in the community that security and protection of private user information are a prerequisite for the deployment of the technology. This is so precisely because the benefits of VC systems, with the mission to enhance transportation safety and efficiency, are at stake. Without the integration of strong and practical security and privacy enhancing mechanisms, VC systems can be disrupted or disabled, even by relatively unsophisticated attackers. We address this problem within the SeVeCom project, having developed a security architecture that provides a comprehensive and practical solution. We present our results in a set of two articles in this issue. In this first one, we analyze threats and types of adversaries, identify security and privacy requirements, and present a spectrum of mechanisms to secure VC systems. We provide a solution that can be quickly adopted and deployed. In the second article we present our progress toward the implementation of our architecture and results on the performance of the secure VC system, along with a discussion of upcoming research challenges and our related current results.
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paper_title: A Secure Cooperative Approach for Nonline-of-Sight Location Verification in VANET

paper_content:

In vehicular ad hoc networks (VANETs), network services and applications (e.g., safety messages) require an exchange of vehicle and event location information. The data are exchanged among vehicles within each vehicle's respective radio communication range through direct communication. In reality, direct communication is susceptible to interference and blocked by physical obstacles, which prevent the proper exchange of information about localization information. Obstacles can create a state of nonline of sight (NLOS) between two vehicles, which restricts direct communication even when corresponding vehicles exist within each other's physical communication range, thus preventing them from exchanging proper data and affecting the localization services' integrity and reliability. Dealing with such obstacles is a challenge in VANETs as moving obstacles such as trucks are parts of the network and have the same characteristics of a VANET node (e.g., high-speed mobility and change of driving behavior). In this paper, we present a location verification protocol among cooperative neighboring vehicles to overcome an NLOS condition and secure the integrity of localization services for VANETs. The simulation results showed improvement in neighborhood awareness under NLOS conditions. A solution such as that we propose will help to maintain localization service integrity and reliability.
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paper_title: An Efficient Trust Management System for Balancing the Safety and Location Privacy in VANETs

paper_content:

In VANETs, how to determine the trustworthiness of event messages has received a great deal of attentions in recent years for improving the safety and location privacy of vehicles. Among these research studies, the accuracy and delay of trustworthiness decision are both important problems. In this paper, we propose a road-side unit (RSU) and beacon-based trust management system, called RaBTM, which aims to prorogate message opinions quickly and thwart internal attackers from sending or forwarding forged messages in privacy-enhanced VANETs. To evaluate the performance and efficiency of the proposed system, we conducted a set of simulations under alteration attacks and bogus message attacks with various adversary ratios. The simulation results show that the proposed system RaBTM is highly resilient to adversarial attacks and performs at least 15% better than weighted vote (WV) scheme.
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paper_title: Selective and confidential message exchange in vehicular ad hoc networks

paper_content:

Vehicular Ad-hoc Networks are a promising and increasingly important paradigm. Their applications range from safety enhancement to mobile entertainment services. However, their deployment requires several security issues to be resolved, particularly, since they rely on insecure wireless communication. In this paper, we propose a cryptographic-based access control framework for vehicles to securely exchange messages in a controlled fashion by integrating moving object modeling techniques with cryptographic policies.
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paper_title: PAAVE: Protocol for Anonymous Authentication in Vehicular Networks Using Smart Cards

paper_content:

Vehicular communications are envisioned to play a substantial role in providing safety in transportation by means of safety message exchange. However, the deployment of vehicular networks is strongly dependent on security and privacy features. In this paper, we present a Protocol for Anonymous Authentication in Vehicular Networks (PAAVE) to address the issue of privacy preservation with authority traceability in vehicular ad hoc networks (VANETs). The proposed protocol is based on smart cards to generate on-the-fly anonymous keys between vehicles and Roadside units (RSUs). PAAVE is lightweight and provides fast anonymous authentication and location privacy while requiring a vehicle to store one cryptographic key. We demonstrate the merits gained by the proposed protocol through extensive analysis and show that PAAVE outperforms existing schemes.
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paper_title: AMOEBA: Robust Location Privacy Scheme for VANET

paper_content:

Communication messages in vehicular ad hoc networks (VANET) can be used to locate and track vehicles. While tracking can be beneficial for vehicle navigation, it can also lead to threats on location privacy of vehicle user. In this paper, we address the problem of mitigating unauthorized tracking of vehicles based on their broadcast communications, to enhance the user location privacy in VANET. Compared to other mobile networks, VANET exhibits unique characteristics in terms of vehicular mobility constraints, application requirements such as a safety message broadcast period, and vehicular network connectivity. Based on the observed characteristics, we propose a scheme called AMOEBA, that provides location privacy by utilizing the group navigation of vehicles. By simulating vehicular mobility in freeways and streets, the performance of the proposed scheme is evaluated under VANET application constraints and two passive adversary models. We make use of vehicular groups for anonymous access to location based service applications in VANET, for user privacy protection. The robustness of the user privacy provided is considered under various attacks.
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paper_title: AMOEBA: Robust Location Privacy Scheme for VANET

paper_content:

Communication messages in vehicular ad hoc networks (VANET) can be used to locate and track vehicles. While tracking can be beneficial for vehicle navigation, it can also lead to threats on location privacy of vehicle user. In this paper, we address the problem of mitigating unauthorized tracking of vehicles based on their broadcast communications, to enhance the user location privacy in VANET. Compared to other mobile networks, VANET exhibits unique characteristics in terms of vehicular mobility constraints, application requirements such as a safety message broadcast period, and vehicular network connectivity. Based on the observed characteristics, we propose a scheme called AMOEBA, that provides location privacy by utilizing the group navigation of vehicles. By simulating vehicular mobility in freeways and streets, the performance of the proposed scheme is evaluated under VANET application constraints and two passive adversary models. We make use of vehicular groups for anonymous access to location based service applications in VANET, for user privacy protection. The robustness of the user privacy provided is considered under various attacks.
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paper_title: V-Tokens for Conditional Pseudonymity in VANETs

paper_content:

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.
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paper_title: GSIS: A Secure and Privacy-Preserving Protocol for Vehicular Communications

paper_content:

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.
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paper_title: PAACP: A portable privacy-preserving authentication and access control protocol in vehicular ad hoc networks

paper_content:

Recently, several studies addressed security and privacy issues in vehicular ad hoc networks (VANETs). Most of them focused on safety applications. As VANETs will be available widely, it is anticipated that Internet services could be accessed through VANETs in the near future. Thus, non-safety applications for VANETs would rise in popularity. This paper proposes a novel portable privacy-preserving authentication and access control protocol, named PAACP, for non-safety applications in VANETs. In addition to the essential support of authentication, key establishment, and privacy preservation, PAACP is developed to provide sophisticated differentiated service access control, which will facilitate the deployment of a variety of non-safety applications. Besides, the portability feature of PAACP can eliminate the backend communications with service providers. Therefore, better performance and scalability can be achieved in PAACP.
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paper_title: Secure Vehicle-to-roadside Communication Protocol Using Certificate-based Cryptosystem

paper_content:

AbstractAs various applications of vehicular ad hoc networks (VANETs) have been proposed, security has become one of the big research challenges and is receiving increasing attention. In this paper, we propose a secure and an efficient vehicle-to-roadside communication protocol by using the recently developed concepts of a certificate-based cryptosystem. The proposed approach combines the best aspects of identity-based public key cryptography approaches (implicit certification) and traditional public key infrastructure approaches (no key escrow). As compared with the previous works, which were implemented with the traditional public key infrastructure and identity-based public key cryptography, the proposed approach is more secure and efficient.
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paper_title: V-Tokens for Conditional Pseudonymity in VANETs

paper_content:

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.
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paper_title: Eviction of Misbehaving and Faulty Nodes in Vehicular Networks

paper_content:

Vehicular networks (VNs) are emerging, among civilian applications, as a convincing instantiation of the mobile networking technology. However, security is a critical factor and a significant challenge to be met. Misbehaving or faulty network nodes have to be detected and prevented from disrupting network operation, a problem particularly hard to address in the life-critical VN environment. Existing networks rely mainly on node certificate revocation for attacker eviction, but the lack of an omnipresent infrastructure in VNs may unacceptably delay the retrieval of the most recent and relevant revocation information; this will especially be the case in the early deployment stages of such a highly volatile and large-scale system. In this paper, we address this specific problem. We propose protocols, as components of a framework, for the identification and local containment of misbehaving or faulty nodes, and then for their eviction from the system. We tailor our design to the VN characteristics and analyze our system. Our results show that the distributed approach to contain nodes and contribute to their eviction is efficiently feasible and achieves a sufficient level of robustness.
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paper_title: A Secure Cooperative Approach for Nonline-of-Sight Location Verification in VANET

paper_content:

In vehicular ad hoc networks (VANETs), network services and applications (e.g., safety messages) require an exchange of vehicle and event location information. The data are exchanged among vehicles within each vehicle's respective radio communication range through direct communication. In reality, direct communication is susceptible to interference and blocked by physical obstacles, which prevent the proper exchange of information about localization information. Obstacles can create a state of nonline of sight (NLOS) between two vehicles, which restricts direct communication even when corresponding vehicles exist within each other's physical communication range, thus preventing them from exchanging proper data and affecting the localization services' integrity and reliability. Dealing with such obstacles is a challenge in VANETs as moving obstacles such as trucks are parts of the network and have the same characteristics of a VANET node (e.g., high-speed mobility and change of driving behavior). In this paper, we present a location verification protocol among cooperative neighboring vehicles to overcome an NLOS condition and secure the integrity of localization services for VANETs. The simulation results showed improvement in neighborhood awareness under NLOS conditions. A solution such as that we propose will help to maintain localization service integrity and reliability.
---
paper_title: AMOEBA: Robust Location Privacy Scheme for VANET

paper_content:

Communication messages in vehicular ad hoc networks (VANET) can be used to locate and track vehicles. While tracking can be beneficial for vehicle navigation, it can also lead to threats on location privacy of vehicle user. In this paper, we address the problem of mitigating unauthorized tracking of vehicles based on their broadcast communications, to enhance the user location privacy in VANET. Compared to other mobile networks, VANET exhibits unique characteristics in terms of vehicular mobility constraints, application requirements such as a safety message broadcast period, and vehicular network connectivity. Based on the observed characteristics, we propose a scheme called AMOEBA, that provides location privacy by utilizing the group navigation of vehicles. By simulating vehicular mobility in freeways and streets, the performance of the proposed scheme is evaluated under VANET application constraints and two passive adversary models. We make use of vehicular groups for anonymous access to location based service applications in VANET, for user privacy protection. The robustness of the user privacy provided is considered under various attacks.
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paper_title: Defense against Sybil attack in vehicular ad hoc network based on roadside unit support

paper_content:

In this paper, we propose a timestamp series approach to defend against Sybil attack in a vehicular ad hoc network (VANET) based on roadside unit support. The proposed approach targets the initial deployment stage of VANET when basic roadside unit (RSU) support infrastructure is available and a small fraction of vehicles have network communication capability. Unlike previously proposed schemes that require a dedicated vehicular public key infrastructure to certify individual vehicles, in our approach RSUs are the only components issuing the certificates. Due to the differences of moving dynamics among vehicles, it is rare to have two vehicles passing by multiple RSUs at exactly the same time. By exploiting this spatial and temporal correlation between vehicles and RSUs, two messages will be treated as Sybil attack issued by one vehicle if they have the similar timestamp series issued by RSUs. The timestamp series approach needs neither vehicular-based public-key infrastructure nor Internet accessible RSUs, which makes it an economical solution suitable for the initial stage of VANET.
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paper_title: Detecting and correcting malicious data in VANETs

paper_content:

In order to meet performance goals, it is widely agreed that vehicular ad hoc networks (VANETs) must rely heavily on node-to-node communication, thus allowing for malicious data traffic. At the same time, the easy access to information afforded by VANETs potentially enables the difficult security goal of data validation. We propose a general approach to evaluating the validity of VANET data. In our approach a node searches for possible explanations for the data it has collected based on the fact that malicious nodes may be present. Explanations that are consistent with the node's model of the VANET are scored and the node accepts the data as dictated by the highest scoring explanations. Our techniques for generating and scoring explanations rely on two assumptions: 1) nodes can tell "at least some" other nodes apart from one another and 2) a parsimony argument accurately reflects adversarial behavior in a VANET. We justify both assumptions and demonstrate our approach on specific VANETs.
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paper_title: A Security Framework with Strong Non-Repudiation and Privacy in VANETs

paper_content:

This paper proposes a security framework with strong non-repudiation and privacy using new approach of ID-based cryptosystem in VANETs. To remove the overheads of certificate management in PKI, security frameworks using an ID-based cryptosystem are proposed. These systems, however, cannot guarantee strong non-repudiation and private communication since they suffer from the inherent weakness of an ID-based cryptosystem like the key escrow problem. The key idea of this paper is that the ID of the third-party is used as the verifier of vehicle's ID and self-generated RSA public key instead of using the ID of the peers. Our scheme provides strong nonrepudiation and privacy preservation without the inherent weaknesses of an ID-based cryptosystem in VANETs. Also, the proposed scheme is efficient in terms of signature and verification time for safety-related applications.
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paper_title: Overview of security issues in Vehicular Ad-hoc Networks

paper_content:

Vehicular ad-hoc networks (VANETs) are a promising communication scenario. Several new applications are envisioned, which will improve traffic management and safety. Nevertheless, those applications have stringent security requirements, as they affect road traffic safety. Moreover, VANETs face several security threats. As VANETs present some unique features (e.g. high mobility of nodes, geographic extension, etc.) traditional security mechanisms are not always suitable. Because of that, a plethora of research contributions have been presented so far. This chapter aims to describe and analyze the most representative VANET security developments.
---
paper_title: ASPE: attribute-based secure policy enforcement in vehicular ad hoc networks

paper_content:

Vehicular ad hoc networks (VANETs) are usually operated among vehicles moving at high speeds, and thus their communication relations can be changed frequently. In such a highly dynamic environment, establishing trust among vehicles is difficult. To solve this problem, we propose a flexible, secure and decentralized attribute based secure key management framework for VANETs. Our solution is based on attribute based encryption (ABE) to construct an attribute based security policy enforcement (ASPE) framework. ASPE considers various road situations as attributes. These attributes are used as encryption keys to secure the transmitted data. ASPE is flexible in that it can dynamically change encryption keys depending on the VANET situations. At the same time, ASPE naturally incorporates data access control policies on the transmitted data. ASPE provides an integrated solution to involve data access control, key management, security policy enforcement, and secure group formation in highly dynamic vehicular communication environments. Our performance evaluations show that ASPE is efficient and it can handle large amount of data encryption/decryption flows in VANETs.
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paper_title: SAT: situation-aware trust architecture for vehicular networks

paper_content:

Establishing trust in vehicular networks is a critical but also difficult task. In this position paper, we present a new trust architecture and model - Situation-Aware Trust (SAT) - to address several important trust issues in vehicular networks that we believe are essential to overcome the weaknesses of the current vehicular network security and trust models. Our model also strengthens the tie between Internet infrastructure. The new SAT includes three main components: (a) an attribute based policy control model for highly dynamic communication environments, (b) a proactive trust model to build trust among vehicles and prevent the breakage of the existing trust, and (c) a social network based trust system to enhance trust and to allow the set up of a decentralized trust framework when the vehicular network is under infrastructure failure or under attacks.
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paper_title: An Efficient Anonymous Authentication Protocol for Secure Vehicular Communications

paper_content:

As vehicular communications bring the promise of improved road safety and optimized road traffic through cooperative systems applications, it becomes a prerequisite to make vehicular communications secure for the successful deployment of vehicular ad hoc networks. In this paper, we propose an efficient authentication protocol with anonymous public key certificates for secure vehicular communications. The proposed protocol follows a system model to issue on-the-fly anonymous public key certificates to vehicles by road-side units. In order to design an efficient authentication protocol, we consider a key-insulated signature scheme for certifying anonymous public keys of vehicles to the system model. We demonstrate experimental results to confirm that the proposed protocol has better performance than other protocols based on group signature schemes.
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paper_title: DESCV--A Secure Wireless Communication Scheme for Vehicle ad hoc Networking

paper_content:

As an indispensable part of intelligent transportation system (ITS), inter-vehicle communication (IVC) emerges as an important research topic. The inter-vehicle communication works based on vehicular ad hoc networking (VANET), and provides communications among different vehicles. The wide applications of VANET helps to improve driving safety with the help of traffic information updates. To ensure that messages can be delivered effectively, the security in VANET becomes a critical issue. Conventional security systems rely heavily on centralized infrastructure to perform security operations such as key assignment and management, which may not suit well for VANET due to its high mobility and ad hoc links. Some works suggested that vehicles should be connected to fixed devices such as road side units (RSUs), but this requires deployment of a large number of costly RSUs in a specific area. This paper is focused on the issues on decentralized IVC without fixed infrastructure and proposes a method for Dynamic Establishment of Secure Communications in VANET (DESCV), which works in particular well for VANET communication key management when centralistic infrastructure or RSU is not available. We will demonstrate through synergy analysis and simulations that DESCV performs well in providing secure communications among vehicles traveling at a relative velocity as high as 240 km/h.
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paper_title: V-Tokens for Conditional Pseudonymity in VANETs

paper_content:

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.
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paper_title: A mechanism to enforce privacy in vehicle-to-infrastructure communication

paper_content:

Privacy-related issues are crucial for the wide diffusion of Vehicular Communications (VC). In particular, traffic analysis is one of the subtler threats to privacy in VC. In this paper we first briefly review current work in literature addressing privacy issues and survey vehicular mobility models. Then we present VIPER: a Vehicle-to-Infrastructure communication Privacy Enforcement pRotocol. VIPER is inspired to solutions provided for the Internet-mix-and cryptography-universal re-encryption. The protocol is shown to be resilient to traffic analysis attacks and analytical results suggest that it also performs well with respect to key performance indicators: queue occupancy, message path length and message delivery time; simulation results support our analytical findings. Finally, a comprehensive analysis has been performed to assess the overhead introduced by our mechanism. Simulation results show that the overhead introduced by VIPER in terms of extra bits required, computations, time delay, and message overhead is feasible even for increasing requirements on the security of the underlying cryptographic mechanisms.
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paper_title: Autonomous Certification with List-Based Revocation for Secure V2V Communication

paper_content:

Privacy and authenticity are two essential security attributes of secure Vehicle-to-Vehicle communications. Pseudonymous Public Key Infrastructure (PPKI), an extension of standard PKI, has been proposed to achieve these security attributes. In Pseudonymous PKI, a user needs certificates or pseudonyms periodically from the Certificate Authority (CA) to authenticate messages anonymously. But the infrastructure presence to communicate with the CA may not be ubiquitous, at least in the initial development phases of vehicular communication. Another proposal, PKI+ reduces dependence on the CA by allowing users to generate pseudonyms autonomously. However, user revocation in PKI+ is rather inconvenient, since it requires the entire network of non-revoked users to be reconfigured after each such event. In this paper, we propose PKI++, an improvement over PKI+, which brings together the desirable features of PKI and PKI+, namely autonomous certification and list-based revocation. We compare the proposed algorithm with PKI and PKI+, and show revocation to be less costly in PKI++.
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paper_title: Mutual Identification and Key Exchange Scheme in Secure VANETs Based on Group Signature

paper_content:

This paper proposes an identilication and key exchange scheme in secure VANETs based on group signature. Security requirements such as authentication, conditional privacy, non-repudiation, and confidentiality are required to satisfy various vehicular applications. Although the existinig group sIgnature schemes are suitable for secure vehicular communications, they do not provide mutual identification and key exchange for data confidentiality. The principal idea of this paper is that the proposed scheme allows only one credential to authenticate ephemeral Diffie-Hellman parameters generated be all the session keys. Our scheme achieves security requirements for various VANET-based applications.
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paper_title: GSIS: A Secure and Privacy-Preserving Protocol for Vehicular Communications

paper_content:

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.
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paper_title: Efficient and robust pseudonymous authentication in VANET

paper_content:

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.
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paper_title: AEMA: An Aggregated Emergency Message Authentication Scheme for Enhancing the Security of Vehicular Ad Hoc Networks

paper_content:

To achieve efficient authentication on emergency events in vehicular ad hoc networks, we introduce a novel aggregated emergency message authentication (AEMA) scheme to validate an emergency event. We make use of syntactic aggregation and cryptographic aggregation techniques to dramatically reduce the transmission cost, and adopt batch verification technique for efficient emergency messages verification. Compared with existing emergency message authentication approaches, our scheme shows the superiority on generality, enhanced security and efficiency.
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paper_title: PAACP: A portable privacy-preserving authentication and access control protocol in vehicular ad hoc networks

paper_content:

Recently, several studies addressed security and privacy issues in vehicular ad hoc networks (VANETs). Most of them focused on safety applications. As VANETs will be available widely, it is anticipated that Internet services could be accessed through VANETs in the near future. Thus, non-safety applications for VANETs would rise in popularity. This paper proposes a novel portable privacy-preserving authentication and access control protocol, named PAACP, for non-safety applications in VANETs. In addition to the essential support of authentication, key establishment, and privacy preservation, PAACP is developed to provide sophisticated differentiated service access control, which will facilitate the deployment of a variety of non-safety applications. Besides, the portability feature of PAACP can eliminate the backend communications with service providers. Therefore, better performance and scalability can be achieved in PAACP.
---
paper_title: Secure Vehicle-to-roadside Communication Protocol Using Certificate-based Cryptosystem

paper_content:

AbstractAs various applications of vehicular ad hoc networks (VANETs) have been proposed, security has become one of the big research challenges and is receiving increasing attention. In this paper, we propose a secure and an efficient vehicle-to-roadside communication protocol by using the recently developed concepts of a certificate-based cryptosystem. The proposed approach combines the best aspects of identity-based public key cryptography approaches (implicit certification) and traditional public key infrastructure approaches (no key escrow). As compared with the previous works, which were implemented with the traditional public key infrastructure and identity-based public key cryptography, the proposed approach is more secure and efficient.
---
paper_title: A Security Framework with Strong Non-Repudiation and Privacy in VANETs

paper_content:

This paper proposes a security framework with strong non-repudiation and privacy using new approach of ID-based cryptosystem in VANETs. To remove the overheads of certificate management in PKI, security frameworks using an ID-based cryptosystem are proposed. These systems, however, cannot guarantee strong non-repudiation and private communication since they suffer from the inherent weakness of an ID-based cryptosystem like the key escrow problem. The key idea of this paper is that the ID of the third-party is used as the verifier of vehicle's ID and self-generated RSA public key instead of using the ID of the peers. Our scheme provides strong nonrepudiation and privacy preservation without the inherent weaknesses of an ID-based cryptosystem in VANETs. Also, the proposed scheme is efficient in terms of signature and verification time for safety-related applications.
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paper_title: Secure, selective group broadcast in vehicular networks using dynamic attribute based encryption

paper_content:

Ciphertext-policy attribute-based encryption (CP-ABE) provides an encrypted access control mechanism for broadcasting messages. Basically, a sender encrypts a message with an access control policy tree which is logically composed of attributes; receivers are able to decrypt the message when their attributes satisfy the policy tree. A user's attributes stand for the properties that he currently owns. A user should keep his attributes up-to-date. However, this is not easy in CP-ABE because whenever one attribute changes, the entire private key, which is based on all the attributes, must be changed. In this paper, we introduce fading function, which renders attributes “dynamic” and allows users to update each attribute separately. We study how choosing fading rate for fading function affects the efficiency and security. We also compare our design with CP-ABE and find our scheme performs significantly better under certain circumstance.
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paper_title: A novel secure communication scheme in vehicular ad hoc networks

paper_content:

Vehicular networks are very likely to become the most pervasive and applicable of mobile ad hoc networks in this decade. Vehicular Ad hoc NETwork (VANET) has become a hot emerging research subject, but few academic publications describing its security infrastructure. In this paper, we review the secure infrastructure of VANET, some potential applications and interesting security challenges. To cope with these security challenges, we propose a novel secure scheme for vehicular communication on VANETs. The proposed scheme not only protects the privacy but also maintains the liability in the secure communications by using session keys. We also analyze the robustness of the proposed scheme.
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paper_title: Eviction of Misbehaving and Faulty Nodes in Vehicular Networks

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Vehicular networks (VNs) are emerging, among civilian applications, as a convincing instantiation of the mobile networking technology. However, security is a critical factor and a significant challenge to be met. Misbehaving or faulty network nodes have to be detected and prevented from disrupting network operation, a problem particularly hard to address in the life-critical VN environment. Existing networks rely mainly on node certificate revocation for attacker eviction, but the lack of an omnipresent infrastructure in VNs may unacceptably delay the retrieval of the most recent and relevant revocation information; this will especially be the case in the early deployment stages of such a highly volatile and large-scale system. In this paper, we address this specific problem. We propose protocols, as components of a framework, for the identification and local containment of misbehaving or faulty nodes, and then for their eviction from the system. We tailor our design to the VN characteristics and analyze our system. Our results show that the distributed approach to contain nodes and contribute to their eviction is efficiently feasible and achieves a sufficient level of robustness.
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paper_title: On Data-Centric Trust Establishment in Ephemeral Ad Hoc Networks

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We argue that the traditional notion of trust as a relation among entities, while useful, becomes insufficient for emerging data-centric mobile ad hoc networks. In these systems, setting the data trust level equal to the trust level of the data- providing entity would ignore system salient features, rendering applications ineffective and systems inflexible. This would be even more so if their operation is ephemeral, i.e., characterized by short-lived associations in volatile environments. In this paper, we address this challenge by extending the traditional notion of trust to data-centric trust: trustworthiness attributed to node-reported data per se. We propose a framework for data-centric trust establishment: First, trust in each individual piece of data is computed; then multiple, related but possibly contradictory, data are combined; finally, their validity is inferred by a decision component based on one of several evidence evaluation techniques. We consider and evaluate an instantiation of our framework in vehicular networks as a case study. Our simulation results show that our scheme is highly resilient to attackers and converges stably to the correct decision.
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paper_title: A Secure Cooperative Approach for Nonline-of-Sight Location Verification in VANET

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In vehicular ad hoc networks (VANETs), network services and applications (e.g., safety messages) require an exchange of vehicle and event location information. The data are exchanged among vehicles within each vehicle's respective radio communication range through direct communication. In reality, direct communication is susceptible to interference and blocked by physical obstacles, which prevent the proper exchange of information about localization information. Obstacles can create a state of nonline of sight (NLOS) between two vehicles, which restricts direct communication even when corresponding vehicles exist within each other's physical communication range, thus preventing them from exchanging proper data and affecting the localization services' integrity and reliability. Dealing with such obstacles is a challenge in VANETs as moving obstacles such as trucks are parts of the network and have the same characteristics of a VANET node (e.g., high-speed mobility and change of driving behavior). In this paper, we present a location verification protocol among cooperative neighboring vehicles to overcome an NLOS condition and secure the integrity of localization services for VANETs. The simulation results showed improvement in neighborhood awareness under NLOS conditions. A solution such as that we propose will help to maintain localization service integrity and reliability.
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paper_title: An Efficient Trust Management System for Balancing the Safety and Location Privacy in VANETs

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In VANETs, how to determine the trustworthiness of event messages has received a great deal of attentions in recent years for improving the safety and location privacy of vehicles. Among these research studies, the accuracy and delay of trustworthiness decision are both important problems. In this paper, we propose a road-side unit (RSU) and beacon-based trust management system, called RaBTM, which aims to prorogate message opinions quickly and thwart internal attackers from sending or forwarding forged messages in privacy-enhanced VANETs. To evaluate the performance and efficiency of the proposed system, we conducted a set of simulations under alteration attacks and bogus message attacks with various adversary ratios. The simulation results show that the proposed system RaBTM is highly resilient to adversarial attacks and performs at least 15% better than weighted vote (WV) scheme.
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paper_title: An ID-based Framework Achieving Privacy and Non-Repudiation in Vehicular Ad Hoc Networks

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Security requirements should be integrated into the design of vehicular ad hoc networks (VANETs), which bear unique features like road-safety and life-critical message dissemination. In this paper, we propose a security framework for VANETs to achieve privacy desired by vehicles and non-repudiation required by authorities, in addition to satisfying fundamental security requirements including authentication, message integrity and confidentiality. The proposed framework employs an ID-based cryptosystem where certificates are not needed for authentication. It increases the communication efficiency for VANET applications where the real-time constraint on message delivery should be guaranteed. We also briefly review the requirements for VANET security and verify the fulfillment of our proposed framework against these requirements.
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paper_title: Detecting and correcting malicious data in VANETs

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In order to meet performance goals, it is widely agreed that vehicular ad hoc networks (VANETs) must rely heavily on node-to-node communication, thus allowing for malicious data traffic. At the same time, the easy access to information afforded by VANETs potentially enables the difficult security goal of data validation. We propose a general approach to evaluating the validity of VANET data. In our approach a node searches for possible explanations for the data it has collected based on the fact that malicious nodes may be present. Explanations that are consistent with the node's model of the VANET are scored and the node accepts the data as dictated by the highest scoring explanations. Our techniques for generating and scoring explanations rely on two assumptions: 1) nodes can tell "at least some" other nodes apart from one another and 2) a parsimony argument accurately reflects adversarial behavior in a VANET. We justify both assumptions and demonstrate our approach on specific VANETs.
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paper_title: Selective and confidential message exchange in vehicular ad hoc networks

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Vehicular Ad-hoc Networks are a promising and increasingly important paradigm. Their applications range from safety enhancement to mobile entertainment services. However, their deployment requires several security issues to be resolved, particularly, since they rely on insecure wireless communication. In this paper, we propose a cryptographic-based access control framework for vehicles to securely exchange messages in a controlled fashion by integrating moving object modeling techniques with cryptographic policies.
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paper_title: Secure Traffic Data Propagation in Vehicular Ad hoc Networks

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In vehicular ad hoc network, vehicles can share traffic/emergency information. The information should not be modified/manipulated during transmission without detection. We present two novel approaches to provide reliable traffic information propagation: two-directional data verification, and time-based data verification. The traffic message is sent through two (spatially or temporally spaced) channels. A recipient vehicle verifies the message integrity by checking if data received from both channels are matched. Compared with the popular public-key based security systems, the proposed approaches are much simpler and cheaper to implement, especially during the initial transition stage when a mature VANET network infrastructure does not exist.
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paper_title: Support of Anonymity in VANETs - Putting Pseudonymity into Practice

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Despite great advantages of vehicular ad hoc networks (VANETs), they also introduce challenges with respect to security and privacy. Today, people are more and more concerned about their privacy. Using unique identifiers for communication, a vehicle can easily be located and tracked. Alternatively, a technical solution to protect drivers' privacy is the use of changing pseudonyms. Existing work mainly focuses on algorithms for pseudonym change and neglect practical implications and realizability. For deployment and integration of pseudonymity into a VANET communication system, several issues need to be solved. This paper analyzes the practical challenges and proposes protocol- and implementation-related solutions necessary to turn pseudonymity support into practice. Finally, the paper concludes by means of analysis and measurements that the burden of pseudonymity can be alleviated at reasonable costs and compromises in anonymity support.
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paper_title: PAAVE: Protocol for Anonymous Authentication in Vehicular Networks Using Smart Cards

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Vehicular communications are envisioned to play a substantial role in providing safety in transportation by means of safety message exchange. However, the deployment of vehicular networks is strongly dependent on security and privacy features. In this paper, we present a Protocol for Anonymous Authentication in Vehicular Networks (PAAVE) to address the issue of privacy preservation with authority traceability in vehicular ad hoc networks (VANETs). The proposed protocol is based on smart cards to generate on-the-fly anonymous keys between vehicles and Roadside units (RSUs). PAAVE is lightweight and provides fast anonymous authentication and location privacy while requiring a vehicle to store one cryptographic key. We demonstrate the merits gained by the proposed protocol through extensive analysis and show that PAAVE outperforms existing schemes.
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paper_title: On the efficiency of secure beaconing in VANETs

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Direct inter-vehicle communication enables numerous safety applications like intersection collision warning. Beacons - periodic one-hop link-layer broadcast messages containing, e.g., location, heading, and speed - are the basis for many such applications. For security, current work often requires all messages to be signed and to carry a certificate to ensure integrity and authenticity. However, high beacon frequency of 1 - 10 Hz and dense traffic situations lead to significant communication and computational overhead. In this paper, we propose several mechanisms to significantly reduce this overhead while maintaining a comparable level of security. The general idea is to omit signatures, certificates, or certificate verification in situations where they are not necessarily required. This creates a security-performance trade-off that we analyze in detail. The results show that significant savings can be achieved with only small impact on security.
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paper_title: AMOEBA: Robust Location Privacy Scheme for VANET

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Communication messages in vehicular ad hoc networks (VANET) can be used to locate and track vehicles. While tracking can be beneficial for vehicle navigation, it can also lead to threats on location privacy of vehicle user. In this paper, we address the problem of mitigating unauthorized tracking of vehicles based on their broadcast communications, to enhance the user location privacy in VANET. Compared to other mobile networks, VANET exhibits unique characteristics in terms of vehicular mobility constraints, application requirements such as a safety message broadcast period, and vehicular network connectivity. Based on the observed characteristics, we propose a scheme called AMOEBA, that provides location privacy by utilizing the group navigation of vehicles. By simulating vehicular mobility in freeways and streets, the performance of the proposed scheme is evaluated under VANET application constraints and two passive adversary models. We make use of vehicular groups for anonymous access to location based service applications in VANET, for user privacy protection. The robustness of the user privacy provided is considered under various attacks.
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paper_title: Deploying Proxy Signature in VANETs

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We introduce a verifiable, self authenticating, and anonymous message delivery protocol for VANET communications using different implementations of proxy signature scheme, where RSU-to-OBU, OBU-to- RSU, and OBU-to-OBU message delivery issues have been addressed. An RSU-to-OBU message delivery scheme is developed, in which a message is protected against potential forgery launched by a malicious RSU. Also, a new proxy signature based approach is provided for message integrity and anonymity for the OBU message delivery. The total process is accountable. The security analysis confirms the validity of the proposed protocol.
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paper_title: ID-based Safety Message Authentication for Security and Trust in Vehicular Networks

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We present a safety message authentication scheme for vehicular ad hoc networks using an ID-based signature and verification mechanism. An ID-based technique offers a certificate-less public key verification, while a proxy signature provides flexibilities in message authentication and trust management. In this scheme, we incorporate an ID-based proxy signature framework with the standard ECDSA for VANET's road-side unit (RSU) originated safety application messages. Also, forwarding of signed messages are specially handled to ensure the trust and authentication of RSU's application messages. We claim that this scheme is resilient against all major security threats and also efficient in terms of computation complexity.
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paper_title: Defense against Sybil attack in vehicular ad hoc network based on roadside unit support

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In this paper, we propose a timestamp series approach to defend against Sybil attack in a vehicular ad hoc network (VANET) based on roadside unit support. The proposed approach targets the initial deployment stage of VANET when basic roadside unit (RSU) support infrastructure is available and a small fraction of vehicles have network communication capability. Unlike previously proposed schemes that require a dedicated vehicular public key infrastructure to certify individual vehicles, in our approach RSUs are the only components issuing the certificates. Due to the differences of moving dynamics among vehicles, it is rare to have two vehicles passing by multiple RSUs at exactly the same time. By exploiting this spatial and temporal correlation between vehicles and RSUs, two messages will be treated as Sybil attack issued by one vehicle if they have the similar timestamp series issued by RSUs. The timestamp series approach needs neither vehicular-based public-key infrastructure nor Internet accessible RSUs, which makes it an economical solution suitable for the initial stage of VANET.
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paper_title: Probabilistic key distribution in vehicular networks with infrastructure support

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We propose a probabilistic key distribution protocol for vehicular network that alleviates the burden of traditional public-key infrastructures. Roadside units act as trusted nodes and are used for secret-sharing among vehicles in their vicinity. Secure communication is immediately possible between these vehicles with high probability. Our performance evaluation, which uses both analysis and simulation, shows that high reliability and short dissemination time can be achieved with low complexity.
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Title: Security Models in Vehicular Ad-hoc Networks: A Survey

Section 1: Background. Vehicular Ad-hoc Networks and Security Needs
Description 1: In this section, a brief overview of the main elements appearing in vehicular ad-hoc networks (VANETs) is given, along with the security-related needs usually considered in these networks.

Section 2: Survey Overview and Scope
Description 2: This section provides an overview of the survey, its scope, and the aspects of security models that are considered.

Section 3: Review on Security Models
Description 3: This section presents a revision of the security models considered in VANET-related recent works, addressing the assumptions about the security of vehicular devices, RSUs, TTPs, and attacker features.

Section 4: Standards Position on Security Models
Description 4: This section describes the positions held by relevant standards, such as ISO 21217 and IEEE 1609.2, regarding security models in VANETs.

Section 5: Analysis and Discussion
Description 5: This section analyzes the findings from the survey and standards review, discussing the relevance of the surveyed contributions and the compatibility of different security models.

Section 6: Basic Approach to Compare Security Models
Description 6: This section proposes a systematic classification approach to compare security models, highlighting similarities and differences between different contributions.

Section 7: Related Work
Description 7: This section reviews previous works related to security issues in vehicular ad-hoc networks, providing context and contrast to the presented survey.

Section 8: Conclusions and Future Work
Description 8: This section summarizes the conclusions drawn from the survey and analysis, and suggests directions for future research in the area of security models for vehicular networks.