Efficient lightweight anonymous authentication scheme with certificateless aggregation for VANETs

Recent developments in Internet of Things (IoT) and vehicular ad hoc networks (VANETs) technologies have improved traffic management and safety in several ways. Due to their unique nature, VANET communications still face certain challenges related to achieving basic security requirements and efficiency. Many researchers proposed different authentication schemes based on certificateless aggregate signature (CLAS-based) as the solutions to achieving the security requirements such as privacy-preserving authentication, integrity, unlinkability and non-repudiation as well as attaining high efficiency in VANETs. However, most of the proposed schemes were revealed insecure or highly inefficient in one way or the other. Recently, a CLAS-based authentication scheme in VANETs using fuzzy extractor functions was proposed by Zhou et al.. They claimed that their proposed scheme achieved various security requirements. However, after thorough review and analysis, we demonstrate that the Zhou et al.’s scheme is vulnerable to signatures linkability attacks which can lead to illegal tracking of vehicles in the VANETs. Subsequently, we propose an improved authentication scheme based on CLAS that mitigates the discovered flaws. Besides improving the security, our proposed scheme introduced the utilization of precomputed values in entities with computational and energy constraints. The use of precomputed values which are usually generated offline prior to authentication process enables our scheme attain very lightweight vehicular authentication. Eventually, we demonstrate that our improved scheme is unforgeable in the random oracle model (ROM) under the intractability of elliptic curve discrete logarithm problem (ECDLP). Moreover, we demonstrated the security of our proposed scheme against signatures linkability attacks under the assumption of strong collision-resistance property of the hash functions. Lastly, results of the efficiency analysis have shown that our improved scheme is comparatively better than the other related schemes.