An improved certificateless aggregate signature scheme without bilinear pairings for vehicular ad hoc networks

Certificateless aggregate signature (CL-AS) is a digital signature technique used to achieve improved performance in resource-constrained environments like vehicular ad hoc networks (VANETs) by eliminating the certificate issue in the traditional public key cryptography (PKC), addressing the key escrow problem in identity-based PKC, and utilizing the efficiency benefits of aggregate signature. Recently, an efficient CL-S scheme for VANETs was proposed which the authors claimed to be existentially secure against forgery attacks in the random oracle model. In this paper, the scheme was analyzed and found to be insecure under existing security model. Consequently, we propose a new efficient certificateless aggregate signature scheme for VANETs applications based on elliptic curve cryptography. The proposed scheme does not only meet the privacy and security requirements for VANETs, but supports batch verification, autonomy, and conditional privacy preservation. In addition, the proposed scheme is provably secure against existential forgery on adaptive chosen message attack in the random oracle model based on the hardness assumption of the elliptic curve discrete logarithm problem. Extensive efficiency analysis demonstrates that the performance of the proposed scheme exceeds those of the recent related schemes in terms of computation cost and communication overhead. (c) 2018 Elsevier Ltd. All rights reserved.