Due to the growing number of vehicles on the roads worldwide, road traffic accidents are currently recognized as a major public safety problem. In this context, connected vehicles are considered as the key enabling technology to improve road safety and to foster the emergence of next generation cooperative intelligent transport systems (ITS). Through the use of wireless communication technologies, the deployment of ITS will enable vehicles to autonomously communicate with other nearby vehicles and roadside infrastructures and will open the door for a wide range of novel road safety and driver assistive applications. However, connecting wireless-enabled vehicles to external entities can make ITS applications vulnerable to various security threats, thus impacting the safety of drivers. This article reviews the current research challenges and opportunities related to the development of secure and safe ITS applications. It first explores the architecture and main characteristics of ITS systems and surveys the key enabling standards and projects. Then, various ITS security threats are analyzed and classified, along with their corresponding cryptographic countermeasures. Finally, a detailed ITS safety application case study is analyzed and evaluated in light of the European ETSI TC ITS standard. An experimental test-bed is presented, and several elliptic curve digital signature algorithms (ECDSA) are benchmarked for signing and verifying ITS safety messages. To conclude, lessons learned, open research challenges and opportunities are discussed.

Cooperative Intelligent Transportation System (C-ITS) enables inter-networking of vehicles for alerts exchanging in order to improve road safety. While this technology is about to enter the market in the upcoming years, critical questions related to the communication security continue to be challenging research concerns. Current solutions to secure inter-vehicle communication depend mainly on the use of digital certificates for authentication. However, such an approach imposes significant overhead on vehicles since it is computationally demanding and requires validation of the certificate within a limited period. In addition, relying on a central node for deciding on issuing and revoking certificates introduces a single point of failure and could even risk the safety of motorists. In this paper, we propose the use of Blockchain to keep track of the certificate of each vehicle (valid or revoked) in distributed and immutable records. In essence we replace certificate verification with a lightweight blockchain-based authentication approach. In addition, we propose a fully distributed vehicle admission/revocation scheme. We show that our scheme could alleviate the computation overhead and enhance the response time while improving the overall system security.

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Connecting vehicles securely and reliably is pivotal to the implementation of next generation ITS applications of smart cities. With continuously growing security threats, vehicles could be exposed to a number of service attacks that could put their safety at stake. To address this concern, both US and European ITS standards have selected Elliptic Curve Cryptography (ECC) algorithms to secure vehicular communications. However, there is still a lack of benchmarking studies on existing security standards in real-world settings. In this paper, we first analyze the security architecture of the ETSI ITS standard. We then implement the ECC based digital signature and encryption procedures using an experimental test-bed and conduct an extensive benchmark study to assess their performance which depends on factors such as payload size, processor speed and security levels. Using network simulation models, we further evaluate the impact of standard compliant security procedures in dense and realistic smart cities scenarios. Obtained results suggest that existing security solutions directly impact the achieved quality of service (QoS) and safety awareness of vehicular applications, in terms of increased packet inter-arrival delays, packet and cryptographic losses, and reduced safety awareness in safety applications. Finally, we summarize the insights gained from the simulation results and discuss open research challenges for efficient working of security in ITS applications of smart cities.

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Wormhole attacks enable an attacker with limited resources and no cryptographic material to disrupt wireless networks. In a wormhole attack, an attacker records packets (or bits) at one location in the network, tunnels them (possibly selectively) to another location and retransmits them there into the network. In this paper, we present an algorithm for detecting and thus defending against wormhole attacks in wireless multihop networks. This algorithm uses only local and neighborhood information without requiring clock synchronization, location information or dedicated hardware. Moreover, the algorithm is independent of wireless communication models. We present simulation results for grid-like topologies and for random topologies and show that the algorithm is able to detect wormhole attacks in all cases whereas the number of false alarms (false detections) decreases rapidly if the network is sufficiently dense.

Wireless sensor networks (WSNs) are composed of numerous low-cost, low-power sensor nodes communicating at short distance through wireless links. Sensors are densely deployed to collect and transmit data of the physical world to one or few destinations called the sinks. Because of open deployment in hostile environment and the use of low-cost materials, powerful adversaries could capture them to extract sensitive information (encryption keys, identities, addresses, etc.). When nodes may be compromised, "beyond cryptography" algorithmic solutions must be envisaged to complement the cryptographic solutions. This paper addresses the problem of nodes replication; that is, an adversary captures one or several nodes and inserts duplicated nodes at any location in the network. If no specific detection mechanisms are established, the attacker could lead many insidious attacks. In this work, we first introduce a new hierarchical distributed algorithm for detecting node replication attacks using a Bloom filter mechanism and a cluster head selection (see also Znaidi et al. (2009)). We present a theoretical discussion on the bounds of our algorithm. We also perform extensive simulations of our algorithm for random topologies, and we compare those results with other proposals of the literature. Finally, we show the effectiveness of our algorithm and its energy efficiency.

Wireless Sensor Network (WSN) technology is now mature enough to be used in numerous application domains. However, due to the restricted amount of energy usually allocated to each node, a crucial property of interest for the users is the minimal lifetime of the network. In practice, this value strongly depends both on the design choices performed for each network element (hardware architecture, communication protocols, etc.) and on the whole execution environment (physical environment, execution platform, network topology, etc.). We propose here an original approach to evaluate this minimal network lifetime based on modelchecking techniques. It consists first in designing a timed model of the entire network behavior (taking into account its execution environment), and then to compute on the state space associated to this model the shortest execution sequences (from a temporal point of view) leading to some states considered as "terminal" (from the network lifetime point of view). This approach is illustrated on a concrete example of a WSN application to compare the influence on the network lifetime of two classical routing algorithms.