A privacy-preserving certificate-less aggregate signature scheme with detectable invalid signatures for VANETs

Vehicular Ad-hoc Networks (VANETs) have significantly improved the efficiency of traffic systems, but there are many security concerns, such as reliable message exchange and privacy-preserving. Besides, under resource-limited conditions, many signed safety-related messages need to be verified in a short period of time. For such, many Certificate-Less Aggregate Signature (CLAS) schemes are proposed. However, some existing CLAS schemes need an efficient algorithm to detect invalid signatures when aggregate verification fails or the proposed algorithms have some unnecessary computation overhead. To overcome such issues, we propose an efficient CLAS scheme that not only fulfills security requirements in VANETs but also provides an improved algorithm to detect invalid signatures with the corresponding real identities. In addition, under the Random Oracle Model (ROM) based Computational Diffie-Hellman (CDH) assumption, we demonstrate that the proposed CLAS scheme is existentially unforgeable under adaptively chosen message attacks (EUF-ACMAs). Performance analysis shows that the proposed scheme is more advantageous in terms of computation overhead and security than other existing schemes.