An Efficient and Practical Conditional Privacy-Preserving Aggregate Authentication for Vehicular Ad-Hoc Networks

Recently, Zhu et al. introduced a conditional privacy-preserving authentication scheme based on certificateless aggregate signature (CLAS) for vehicular ad-hoc networks (VANETs). In this paper, we put forward a re-cryptanalysis to their CLAS and provide four concrete forgeries to disprove its security for VANETs. In addition, we also propose a provably secure CLAS scheme with a new aggregate algorithm for VANETs. This algorithm guarantees that the validities of all single signatures are publicly deduced to the validity of a concise aggregate signature. Performance analysis shows that our scheme not only supports public verification but also has short signature size and/or low computation cost compared with existing related works, which is very practical for VANETs.