Cryptanalysis and improvement of certificateless aggregate signature with conditional privacy-preserving for vehicular sensor networks

Secure aggregate signature schemes have attracted more concern due to their wide application in resource constrained environment. Recently, Horng et al. [S. J. Horng et al., An efficient certificateless aggregate signature with conditional privacy-preserving for vehicular sensor networks, Information Sciences 317 (2015) 48-66] proposed an efficient certificateless aggregate signature with conditional privacy-preserving for vehicular sensor networks. They claimed that their scheme was provably secure against existential forgery on adaptively chosen message attack in the random oracle model. In this paper, we show that their scheme is insecure against a malicious-but-passive KGC under existing security model. Further, we propose an improved certificateless aggregate signature.