Wireless broadcast transmission technology enables vehicles to communicate with other nearby vehicles and with nearby fixed equipment. Vehicles and equipment within transmission range establish a self-organizing network called Vehicular Ad-hoc Network (VANET). The communication in VANETs is vulnerable to message manipulation attacks. Thus, mechanisms should be applied to ensure both the authenticity and integrity of the data broadcast. Any cryptographic technique employed for authentication requires the use of a cryptographic key, and mechanisms to restore the system quickly when either long-term and short-term cryptographic keying material are leaked or expired. Such mechanisms must be carefully designed to satisfy both perfect-forward-secrecy and security against known-key attacks. To achieve this, there should be no direct dependencies among keying material. Unfortunately, many existing proposals for authentication are not fully effective in VANETs, since many of them do not take a key-management mechanism into consideration or they fail to satisfy the requirements for secure key-update. In this paper, we first present a case study demonstrating that dependency among keying material is an exploitable vulnerability that violates perfect-forward-secrecy, and results in known-key attacks and message forgery attacks. Secondly, we propose a new cryptographic-key update protocol that consists of two sub-protocols: a long-term-key update protocol (for updating the long-term cryptographic keying material) and a short-term-key update protocol (for session-key establishment). Our scheme is accompanied by both security and efficiency analysis: we provide a formal security proof and demonstrate efficiency by conducting extensive performance analysis. This is compared with the security and efficiency of existing schemes in public literature.

Wireless broadcast transmission enables Inter-vehicle or Vehicle-to-Vehicle (V2V) communication among nearby vehicles. This communication supports latency-critical applications for improved safety and maybe optimized traffic. However, V2V communication is vulnerable to cyber attacks involving message manipulation. Mechanisms are required to ensure both authenticity and integrity of broadcast data, while maintaining drivers privacy against surveillance. Considering the limited computational resources of vehicles and the possibility of high traffic density scenarios, authentication processes should have low computational overhead. Prior research has produced multiple authentication protocol proposals based on digital signatures, hash functions, or Message Authentication Codes (MACs). To date, there is no computationally efficient secure broadcast authentication scheme tolerable by the vehicles resource-constrained On-Board Units (OBUs) for latency-critical applications in heavy traffic conditions. This paper provides a new secure, efficient, and privacy-preserving scheme proposing Anonymous Lightweight Inter-vehicle (ALI) broadcast authentication with encryption. ALI provides a high level of anonymity by combining a message authentication scheme with beacon encryption. The cryptographic overhead for V2V communication in the ALI scheme is only 149 bytes, and can handle authentication of approximately 700 broadcast messages every 100 milliseconds. This demonstrates the suitability of the ALI scheme in heavy traffic scenarios. We show the security and efficiency of our proposal by conducting security proof and performance analysis.

In the near future, intelligent vehicles will be connected via wireless communication links, forming Vehicular Ad-hoc Networks (VANETs). This has potential to improve road safety and to optimize traffic. However, if the communications are not secure, VANETs are vulnerable to cyber attacks involving message manipulation. Research on this problem has produced multiple authentication protocols based on bilinear pairings (a variant of elliptic curve cryptography). The efficiency of such authentication schemes must be addressed before they can be used in real-world deployments. Standards bodies have begun standardizing various pairing-based schemes. The IEEE 1609.2 security standard has not yet selected any pairing-based scheme, leaving the settings related to pairing-based cryptography in the vehicular environments unspecified. In this work, we investigate the efficiency of pairing-based cryptographic primitives over the Barreto-Lynn-Scott and Barreto-Naehrig pairing friendly elliptic curves recommended in the IETF and ISO standards, to determine their suitability for practical application. We implement the algorithms and evaluate the effect of cryptographic pairings using theoretical and experimental analysis of four well-known pairing-based short signature schemes, including: Boneh-Lynn-Shacham, Boneh-Boyen, Zhang-Safavi-Susilo, and Boneh-Gentry-Lynn-Shacham. We use metrics including CPU clock cycles per operation, average computation time in milliseconds, and signature/public key size in bits to estimate the cost of implementing cryptographic pairings on modern processors. We demonstrate the effect of pairing-based cryptography on authentication in vehicular networks. We investigate a high-density highway scenario and show that a crash is possible, as a result of the evaluated authentication delay. We share our findings ahead of the IEEE 1609.2 recommendations for the use of cryptographic pairings.