A trust-driven privacy architecture for vehicular ad-hoc networks

Vehicular Ad-Hoc NETworks (VANETs) are an emerging technology which aims to improve road safety by preventing and reducing traffic accidents. While VANETs offer a great variety of promising applications, such as, safety-related and infotainment applications, they remain a number of security and privacy related research challenges that must be addressed. A common approach to security issues widely adopted in VANETs is the use of Public Key Infrastructures (PKI) and digital certificates in order to enable authentication, authorization and confidentiality. These approaches usually rely on a large set of regional Certification Authorities (CAs). Despite the advantages of PKI-based approaches, there are two main problems that arise, i) the secure interoperability among the different and usually unknown- issuing CAs, and ii) the sole use of PKI in a VANET environment cannot prevent privacy related attacks, such as, linking a vehicle with an identifier, tracking vehicles ¿big brother scenario" and user profiling. Additionally, since vehicles in VANETs will be able to store great amounts of information including private information, unauthorized access to such information should be carefully considered. This thesis addresses authentication and interoperability issues in vehicular communications, considering an inter-regional scenario where mutual authentication between nodes is needed. To provide interoperability between vehicles and services among different domains, an Inter-domain Authentication System (AS) is proposed. The AS supplies vehicles with a trusted set of authentication credentials by implementing a near real-time certificate status service. The proposed AS also implements a mechanism to quantitatively evaluate the trust level of a CA, in order to decide on-the-y if an interoperability relationship can be created. This research work also contributes with a Privacy Enhancing Model (PEM) to deal with important privacy issues in VANETs. The PEM consists of two PKI-based privacy protocols: i) the Attribute-Based Privacy (ABP) protocol, and ii) the Anonymous Information Retrieval (AIR) protocol. The ABP introduces Attribute-Based Credentials (ABC) to provide conditional anonymity and minimal information disclosure, which overcome with the privacy issues related to linkability (linking a vehicle with an identifier) and vehicle tracking (big brother scenario). The AIR protocol addresses user profiling when querying Service Providers (SPs), by relying in a user collaboration privacy protocol based on query forgery and permutation; and assuming that neither participant nodes nor SPs could be completely trusted. Finally, the Trust Validation Model (TVM) is proposed. The TVM supports decision making by evaluating entities trust based on context information, in order to provide i) access control to driver and vehicle's private information, and ii) public information trust validation

Research on security and privacy in vehicular ad hoc networks

Los sistemas de redes ad hoc vehiculares (VANET) tienen como objetivo proporcionar una plataforma para diversas aplicaciones que pueden mejorar la seguridad vial, la eficiencia del tráfico, la asistencia a la conducción, la regulación del transporte, etc. o que pueden proveer de una mejor información y entretenimiento a los usuarios de los vehículos. Actualmente se está llevando a cabo un gran esfuerzo industrial y de investigación para desarrollar un mercado que se estima alcance en un futuro varios miles de millones de euros. Mientras que los enormes beneficios que se esperan de las comunicaciones vehiculares y el gran número de vehículos son los puntos fuertes de las VANET, su principal debilidad es la vulnerabilidad a los ataques contra la seguridad y la privacidad.En esta tesis proponemos cuatro protocolos para conseguir comunicaciones seguras entre vehículos. En nuestra primera propuesta empleamos a todas las unidades en carretera (RSU) para mantener y gestionar un grupo en tiempo real dentro de su rango de comunicación. Los vehículos que entren al grupo de forma anónima pueden emitir mensajes vehículo a vehículo (V2V) que inmediatamente pueden ser verificados por los vehículos del mismo grupo (y grupos de vecinos). Sin embargo, en la primera fase del despliegue de este sistema las RSU pueden no estar bien distribuídas. Consecuentemente, se propone un conjunto de mecanismos para hacer frente a la seguridad, privacidad y los requisitos de gestión de una VANET a gran escala sin la suposición de que las RSU estén densamente distribuidas. La tercera propuesta se centra principalmente en la compresión de las evidencias criptográficas que nos permitirán demostrar, por ejemplo, quien era el culpable en caso de accidente. Por último, investigamos los requisitos de seguridad de los sistemas basados en localización (LBS) sobre VANETs y proponemos un nuevo esquema para la preservación de la privacidad de la localización en estos sistemas sobre dichas redes.Vehicular ad hoc network (VANET) systems aim at providing a platform for various applications that can improve traffic safety and efficiency, driver assistance, transportation regulation, infotainment, etc. There is substantial research and industrial effort to develop this market. It is estimated that the market for vehicular communications will reach several billion euros. While the tremendous benefits expected from vehicular communications and the huge number of vehicles are strong points of VANETs, their weakness is vulnerability to attacks against security and privacy.In this thesis, we propose four protocols for secure vehicle communications. In our first proposal, we employ each road-side unit (RSU) to maintain and manage an on-the-fly group within its communication range. Vehicles entering the group can anonymously broadcast vehicle-to-vehicle (V2V) messages, which can be instantly verified by the vehicles in the same group (and neighbor groups). However, at the early stage of VANET deployment, the RSUs may not be well distributed. We then propose a set of mechanisms to address the security, privacy, and management requirements of a large-scale VANET without the assumption of densely distributed RSUs. The third proposal is mainly focused on compressing cryptographic witnesses in VANETs. Finally, we investigate the security requirements of LBS in VANETs and propose a new privacy-preserving LBS scheme for those networks

Secure and Authenticated Message Dissemination in Vehicular ad hoc Networks and an Incentive-Based Architecture for Vehicular Cloud

Vehicular ad hoc Networks (VANETs) allow vehicles to form a self-organized network. VANETs are likely to be widely deployed in the future, given the interest shown by industry in self-driving cars and satisfying their customers various interests. Problems related to Mobile ad hoc Networks (MANETs) such as routing, security, etc.have been extensively studied. Even though VANETs are special type of MANETs, solutions proposed for MANETs cannot be directly applied to VANETs because all problems related to MANETs have been studied for small networks. Moreover, in MANETs, nodes can move randomly. On the other hand, movement of nodes in VANETs are constrained to roads and the number of nodes in VANETs is large and covers typically large area. The following are the contributions of the thesis. Secure, authenticated, privacy preserving message dissemination in VANETs: When vehicles in VANET observe phenomena such as accidents, icy road condition, etc., they need to disseminate this information to vehicles in appropriate areas so the drivers of those vehicles can take appropriate action. When such messages are disseminated, the authenticity of the vehicles disseminating such messages should be verified while at the same time the anonymity of the vehicles should be preserved. Moreover, to punish the vehicles spreading malicious messages, authorities should be able to trace such messages to their senders when necessary. For this, we present an efficient protocol for the dissemination of authenticated messages. Incentive-based architecture for vehicular cloud: Due to the advantages such as exibility and availability, interest in cloud computing has gained lot of attention in recent years. Allowing vehicles in VANETs to store the collected information in the cloud would facilitate other vehicles to retrieve this information when they need. In this thesis, we present a secure incentive-based architecture for vehicular cloud. Our architecture allows vehicles to collect and store information in the cloud; it also provides a mechanism for rewarding vehicles that contributing to the cloud. Privacy preserving message dissemination in VANETs: Sometimes, it is sufficient to ensure the anonymity of the vehicles disseminating messages in VANETs. We present a privacy preserving message dissemination protocol for VANETs

Secure Authentication and Privacy-Preserving Techniques in Vehicular Ad-hoc NETworks (VANETs)

In the last decade, there has been growing interest in Vehicular Ad Hoc NETworks (VANETs). Today car manufacturers have already started to equip vehicles with sophisticated sensors that can provide many assistive features such as front collision avoidance, automatic lane tracking, partial autonomous driving, suggestive lane changing, and so on. Such technological advancements are enabling the adoption of VANETs not only to provide safer and more comfortable driving experience but also provide many other useful services to the driver as well as passengers of a vehicle. However, privacy, authentication and secure message dissemination are some of the main issues that need to be thoroughly addressed and solved for the widespread adoption/deployment of VANETs. Given the importance of these issues, researchers have spent a lot of effort in these areas over the last decade. We present an overview of the following issues that arise in VANETs: privacy, authentication, and secure message dissemination. Then we present a comprehensive review of various solutions proposed in the last 10 years which address these issues. Our survey sheds light on some open issues that need to be addressed in the future

Overview of security issues in Vehicular ad-hoc networks

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

An Efficient Public Key Management System: An Application In Vehicular Ad Hoc Networks

The major purpose of Vehicular Ad Hoc Networks (VANETs) is to provide safety-related message access for motorists to react or make a life-critical decision for road safety enhancement. Accessing safety-related information through the use of VANET communications, therefore, must be protected, as motorists may make critical decisions in response to emergency situations in VANETs. If introducing security services into VANETs causes considerable transmission latency or processing delays, this would defeat the purpose of using VANETs to improve road safety. Current research in secure messaging for VANETs appears to focus on employing certificate-based Public Key Cryptosystem (PKC) to support security. The security overhead of such a scheme, however, creates a transmission delay and introduces a time-consuming verification process to VANET communications. This paper proposes an efficient public key management system for VANETs: the Public Key Registry (PKR) system. Not only does this paper demonstrate that the proposed PKR system can maintain security, but it also asserts that it can improve overall performance and scalability at a lower cost, compared to the certificate-based PKC scheme. It is believed that the proposed PKR system will create a new dimension to the key management and verification services for VANETs

A transparent distributed ledger-based certificate revocation scheme for VANETs

The widespread adoption of Cooperative, Connected, and Automated Mobility (CCAM) applications requires the implementation of stringent security mechanisms to minimize the surface of cyber attacks. Authentication is an effective process for validating user identity in vehicular networks. However, authentication alone is not enough to prevent dangerous attack situations. Existing security mechanisms are not able to promptly revoke the credentials of misbehaving vehicles, thus tolerate malicious actors to remain trusted in the system for a long time. The resulting vulnerability window allows the implementation of complex attacks, thus posing a substantial impairment to the security of the vehicular ecosystem. In this paper we propose a Distributed Ledger-based Vehicular Revocation Scheme that improves the state of the art by providing a vulnerability window lower than 1 s, reducing well-behaved vehicles exposure to sophisticated and potentially dangerous attacks. The proposed scheme harnesses the advantages of the underlying Distributed Ledger Technology (DLT) to implement a privacy-aware revocation process while being fully transparent to all participating entities. Furthermore, it meets the critical message processing times defined by EU and US standards, thus closing a critical gap in the current international standards. Theoretical analysis and experimental validation demonstrate the effectiveness and efficiency of the proposed scheme, where DLT streamlines the revocation operation overhead and delivers an economically viable yet scalable solution against cyber attacks on vehicular systems

Certificate status information distribution and validation in vehicular networks

Vehicular ad hoc networks (VANETs) are emerging as an functional technology for providing a wide range of applications to vehicles and passengers. Ensuring secure functioning is one of the prerequisites for deploying reliable VANETs. The basic solution envisioned to achieve these requirements is to use digital certificates linked to a user by a trusted third party. These certificates can then be used to sign information. Most of the existing solutions manage these certificates by means of a central Certification Authority (CA). According to IEEE 1609.2 standard, vehicular networks will rely on the public key infrastructure (PKI). In PKI, a CA issues an authentic digital certificate for each node in the network. Therefore, an efficient certificate management is crucial for the robust and reliable operation of any PKI. A critical part of any certificate-management scheme is the revocation of certificates. The distribution of certificate status information process, as well as the revocation process itself, is an open research problem for VANETs.In this thesis, firstly we analyze the revocation process itself and develop an accurate and rigorous model for certificate revocation. One of the key findings of our analysis is that the certificate revocation process is statistically self-similar. As none of the currently common formal models for revocation is able to capture the self-similar nature of real revocation data, we develop an ARFIMA model that recreates this pattern. We show that traditional mechanisms that aim to scale could benefit from this model to improve their updating strategies.Secondly, we analyze how to deploy a certificate status checking service for mobile networks and we propose a new criterion based on a risk metric to evaluate cached status data. With this metric, the PKI is able to code information about the revocation process in the standard certificate revocation lists. Thus, users can evaluate a risk function in order to estimate whether a certificate has been revoked while there is no connection to a status checking server. Moreover, we also propose a systematic methodology to build a fuzzy system that assists users in the decision making process related to certificate status checking.Thirdly, we propose two novel mechanisms for distributing and validating certificate status information (CSI) in VANET. This first mechanism is a collaborative certificate status checking mechanism based on the use based on an extended-CRL. The main advantage of this extended-CRL is that the road-side units and repository vehicles can build an efficient structure based on an authenticated hash tree to respond to status checking requests inside the VANET, saving time and bandwidth. The second mechanism aims to optimize the trade- off between the bandwidth necessary to download the CSI and the freshness of the CSI. This mechanism is based on the use of a hybrid delta-CRL scheme and Merkle hash trees, so that the risk of operating with unknown revoked certificates remains below a threshold during the validity interval of the base-CRL, and CAs have the ability to manage this risk by setting the size of the delta-CRLs. Finally, we also analyze the impact of the revocation service in the certificate prices. We model the behavior of the oligopoly of risk-averse certificate providers that issue digital certificates to clients facing iden- tical independent risks. We found the equilibrium in the Bertrand game. In this equilibrium, we proof that certificate providers that offer better revocation information are able to impose higher prices to their certificates without sacrificing market share in favor of the other oligarchs.Las redes vehiculares ad hoc (VANETs) se están convirtiendo en una tecnología funcional para proporcionar una amplia gama de aplicaciones para vehículos y pasajeros. Garantizar un funcionamiento seguro es uno de los requisitos para el despliegue de las VANETs. Sin seguridad, los usuarios podrían ser potencialmente vulnerables a la mala conducta de los servicios prestados por la VANET. La solución básica prevista para lograr estos requisitos es el uso de certificados digitales gestionados a través de una autoridad de certificación (CA). De acuerdo con la norma IEEE 1609.2, las redes vehiculares dependerán de la infraestructura de clave pública (PKI). Sin embargo, el proceso de distribución del estado de los certificados, así como el propio proceso de revocación, es un problema abierto para VANETs.En esta tesis, en primer lugar se analiza el proceso de revocación y se desarrolla un modelo preciso y riguroso que modela este proceso conluyendo que el proceso de revocación de certificados es estadísticamente auto-similar. Como ninguno de los modelos formales actuales para la revocación es capaz de capturar la naturaleza auto-similar de los datos de revocación, desarrollamos un modelo ARFIMA que recrea este patrón. Mostramos que ignorar la auto-similitud del proceso de revocación lleva a estrategias de emisión de datos de revocación ineficientes. El modelo propuesto permite generar trazas de revocación sintéticas con las cuales los esquemas de revocación actuales pueden ser mejorados mediante la definición de políticas de emisión de datos de revocación más precisas. En segundo lugar, se analiza la forma de implementar un mecanismo de emisión de datos de estado de los certificados para redes móviles y se propone un nuevo criterio basado en una medida del riesgo para evaluar los datos de revocación almacenados en la caché. Con esta medida, la PKI es capaz de codificar la información sobre el proceso de revocación en las listas de revocación. Así, los usuarios pueden estimar en función del riesgo si un certificado se ha revocado mientras no hay conexión a un servidor de control de estado. Por otra parte, también se propone una metodología sistemática para construir un sistema difuso que ayuda a los usuarios en el proceso de toma de decisiones relacionado con la comprobación de estado de certificados.En tercer lugar, se proponen dos nuevos mecanismos para la distribución y validación de datos de estado de certificados en VANETs. El primer mecanismo está basado en el uso en una extensión de las listas estandares de revocación. La principal ventaja de esta extensión es que las unidades al borde de la carretera y los vehículos repositorio pueden construir una estructura eficiente sobre la base de un árbol de hash autenticado para responder a las peticiones de estado de certificados. El segundo mecanismo tiene como objetivo optimizar el equilibrio entre el ancho de banda necesario para descargar los datos de revocación y la frescura de los mismos. Este mecanismo se basa en el uso de un esquema híbrido de árboles de Merkle y delta-CRLs, de modo que el riesgo de operar con certificados revocados desconocidos permanece por debajo de un umbral durante el intervalo de validez de la CRL base, y la CA tiene la capacidad de gestionar este riesgo mediante el ajuste del tamaño de las delta-CRL. Para cada uno de estos mecanismos, llevamos a cabo el análisis de la seguridad y la evaluación del desempeño para demostrar la seguridad y eficiencia de las acciones que se emprenden

Location Privacy in VANETs: Improved Chaff-Based CMIX and Privacy-Preserving End-to-End Communication

VANETs communication systems are technologies and defined policies that can be formed to enable ITS applications to provide road traffic efficacy, warning about such issues as environmental dangers, journey circumstances, and in the provision of infotainment that considerably enhance transportation safety and quality. The entities in VANETs, generally vehicles, form part of a massive network known as the Internet of Vehicles (IoV). The deployment of large-scale VANETs systems is impossible without ensuring that such systems are themselves are safe and secure, protecting the privacy of their users. There is a risk that cars might be hacked, or their sensors become defective, causing inaccurate information to be sent across the network. Consequently, the activities and credentials of participating vehicles should be held responsible and quickly broadcast throughout a vast VANETs, considering the accountability in the system. The openness of wireless communication means that an observer can eavesdrop on vehicular communication and gain access or otherwise deduce users' sensitive information, and perhaps profile vehicles based on numerous factors such as tracing their travels and the identification of their home/work locations. In order to protect the system from malicious or compromised entities, as well as to preserve user privacy, the goal is to achieve communication security, i.e., keep users' identities hidden from both the outside world and the security infrastructure and service providers. Being held accountable while still maintaining one's privacy is a difficult balancing act. This thesis explores novel solution paths to the above challenges by investigating the impact of low-density messaging to improve the security of vehicle communications and accomplish unlinkability in VANETs. This is achieved by proposing an improved chaff-based CMIX protocol that uses fake messages to increase density to mitigate tracking in this scenario. Recently, Christian \etall \cite{vaas2018nowhere} proposed a Chaff-based CMIX scheme that sends fake messages under the presumption low-density conditions to enhance vehicle privacy and confuse attackers. To accomplish full unlinkability, we first show the following security and privacy vulnerabilities in the Christian \etall scheme: linkability attacks outside the CMIX may occur due to deterministic data-sharing during the authentication phase (e.g., duplicate certificates for each communication). Adversaries may inject fake certificates, which breaks Cuckoo Filters' (CFs) updates authenticity, and the injection may be deniable. CMIX symmetric key leakage outside the coverage may occur. We propose a VPKI-based protocol to mitigate these issues. First, we use a modified version of Wang \etall's \cite{wang2019practical} scheme to provide mutual authentication without revealing the real identity. To this end, a vehicle's messages are signed with a different pseudo-identity “certificate”. Furthermore, the density is increased via the sending of fake messages during low traffic periods to provide unlinkability outside the mix-zone. Second, unlike Christian \etall's scheme, we use the Adaptive Cuckoo Filter (ACF) instead of CF to overcome the effects of false positives on the whole filter. Moreover, to prevent any alteration of the ACFs, only RUSs distribute the updates, and they sign the new fingerprints. Third, mutual authentication prevents any leakage from the mix zones' symmetric keys by generating a fresh one for each communication through a Diffie–Hellman key exchange. As a second main contribution of this thesis, we focus on the V2V communication without the interference of a Trusted Third Party (TTP)s in case this has been corrupted, destroyed, or is out of range. This thesis presents a new and efficient end-to-end anonymous key exchange protocol based on Yang \etall's \cite{yang2015self} self-blindable signatures. In our protocol, vehicles first privately blind their own private certificates for each communication outside the mix-zone and then compute an anonymous shared key based on zero-knowledge proof of knowledge (PoK). The efficiency comes from the fact that once the signatures are verified, the ephemeral values in the PoK are also used to compute a shared key through an authenticated Diffie-Hellman key exchange protocol. Therefore, the protocol does not require any further external information to generate a shared key. Our protocol also does not require interfacing with the Roadside Units or Certificate Authorities, and hence can be securely run outside the mixed-zones. We demonstrate the security of our protocol in ideal/real simulation paradigms. Hence, our protocol achieves secure authentication, forward unlinkability, and accountability. Furthermore, the performance analysis shows that our protocol is more efficient in terms of computational and communications overheads compared to existing schemes.Kuwait Cultural Offic