A Survey of Security Services, Attacks, and Applications for Vehicular Ad Hoc Networks (VANETs) <s> TESLA-Based Authentication Schemes <s> Multicast stream authentication and signing is an important and challenging problem. Applications include the continuous authentication of radio and TV Internet broadcasts, and authenticated data distribution by satellite. The main challenges are fourfold. First, authenticity must be guaranteed even when only the sender of the data is trusted. Second, the scheme needs to scale to potentially millions of receivers. Third, streamed media distribution can have high packet loss. Finally the system needs to be efficient to support fast packet rates. We propose two efficient schemes, TESLA and EMSS, for secure lossy multicast streams. TESLA (Timed Efficient Stream Loss-tolerant Authentication), offers sender authentication, strong loss robustness, high scalability and minimal overhead at the cost of loose initial time synchronization and slightly delayed authentication. EMSS (Efficient Multi-chained Stream Signature), provides nonrepudiation of origin, high loss resistance, and low overhead, at the cost of slightly delayed verification. <s> BIB001 </s> A Survey of Security Services, Attacks, and Applications for Vehicular Ad Hoc Networks (VANETs) <s> TESLA-Based Authentication Schemes <s> Although much research has been conducted in the area of authentication in wireless networks, vehicular ad-hoc networks (VANETs) pose unique challenges, such as real-time constraints, processing limitations, memory constraints, frequently changing senders, requirements for interoperability with existing standards, extensibility and flexibility for future requirements, etc. No currently proposed technique addresses all of the requirements for message and entity authentication in VANETs. After analyzing the requirements for viable VANET message authentication, we propose a modified version of TESLA, TESLA++, which provides the same computationally efficient broadcast authentication as TESLA with reduced memory requirements. To address the range of needs within VANETs we propose a new hybrid authentication mechanism, VANET authentication using signatures and TESLA++ (VAST), that combines the advantages of ECDSA signatures and TESLA++. Elliptic curve digital signature algorithm (ECDSA) signatures provide fast authentication and non-repudiation, but are computationally expensive. TESLA++ prevents memory and computation-based denial of service attacks. We analyze the security of our mechanism and simulate VAST in realistic highway conditions under varying network and vehicular traffic scenarios. Simulation results show that VAST outperforms either signatures or TESLA on its own. Even under heavy loads VAST is able to authenticate 100% of the received messages within 107ms. VANETs use certificates to achieve entity authentication (i.e., validate senders). To reduce certificate bandwidth usage, we use Hu et al.'s strategy of broadcasting certificates at fixed intervals, independent of the arrival of new entities. We propose a new certificate verification strategy that prevents denial of service attacks while requiring zero additional sender overhead. Our analysis shows that these solutions introduce a small delay, but still allow drivers in a worst case scenario over 3 seconds to respond to a dangerous situation. <s> BIB002 </s> A Survey of Security Services, Attacks, and Applications for Vehicular Ad Hoc Networks (VANETs) <s> TESLA-Based Authentication Schemes <s> Authentication is an essential security requirement in safety-related vehicle-to-vehicle applications in VANETs. TESLA is one of the most popular broadcast source authentication protocols proposed and standardized for this purpose. Having strict time constraints and being prone to GPS synchronization errors make the analysis of this protocol challenging. In this paper, we utilize a timed model checking approach based on timed colored Petri nets to model and verify TESLA considering its time-sensitive behaviors. In this way, we show how neglecting timing aspects in protocol design and in protocol modelling can lead to successfully launched attacks and erroneous analyses respectively, and how its refinement can help improve the protocol's security. Our work extends the problem of analyzing basic TESLA done in previous related works, to one in which TESLA is modelled and verified in a loose synchronization setting, which is the case in VANETs. This new problem definition led to finding new attacks that are directly rooted in the sending times of packets. We show what changes need to be made to TESLA so that its security property be preserved in a loose synchronization condition. <s> BIB003 </s> A Survey of Security Services, Attacks, and Applications for Vehicular Ad Hoc Networks (VANETs) <s> TESLA-Based Authentication Schemes <s> Abstract A vehicular Ad Hoc Network (VANET) is a class of mobile ad hoc network (MANET) which supports, vehicle to vehicle (V2V) and vehicle to infrastructure (V2I) communications. The significant features of VANET includes, self-organization, distributed networking, and highly dynamic topology. The VANET features and its applications to road safety have attracted a lot of interest in industry and academia more so into the research on improvement of transportation systems for saving millions of lives. The transmission of messages in open-access environment like VANET leads to the most critical and challenging security issues. Authentication, data confidentiality, data integrity, data availability, and non-repudiation are crucial components of security in VANET. This paper focuses on the authentication schemes in VANET as it plays a important role in secured communication. The authentication schemes are basically classified into three categories: cryptography techniques, digital signatures, and message verification techniques. The main objective of this paper is to provide a taxonomy of authentication schemes, and discuss their mechanisms, advantages, disadvantages, performance and scope of research. Furthermore, the paper concludes with presentation of open security issues in VANET authentication. <s> BIB004
The symmetric cryptography is further extended to time the efficient stream loss-tolerant authentication (TESLA). In this approach, first, the sender computes MAC using a known key and attaches a MAC to each sending message, and the receiving messages are buffered without authentication at the receiving part. The main disadvantage of TESLA is that the advance synchronization of the clock at receiving side is required with the clock at the sending side. Additionally, TESLA is vulnerable to the DOS attack in terms of memory, which is caused by unregistered vehicles that utilize receiver memory with fake messages BIB004 BIB001 . Jahanian et al. BIB003 introduced a TESLA-based technique. In this technique, the timed method checking the approach based on the timed color Petri model is used to design and verify TESLA. Lately, the researchers have found that the two factors that need to be analyzed first include security efficiency and the percentage of successful attack. Studer et al. BIB002 introduced a modified form of TESLA, which is known as TESLA++, and it provides the same broadcast authentication, which is computationally efficient since TESLA with less memory consumption presented a method to effectively verify the newly RSUs and OBUs, which were encountered during communication. The goal of TESLA++ is to control memory DOS attacks, which can be obtained by receivers' self-generated MAC. This may be lower down the memory requirements for authentication. However, TESLA does not offer multiple hops authentication and non-repudiation BIB004 .