Efficient Certificateless Aggregate Signature Scheme for Performing Secure Routing in VANETs Certificateless public key cryptosystem solves both the complex certificate management problem in the public key cryptosystem based on the PKI and the key escrow issue in the public key cryptosystem based on identity. The aggregator can compress n different signatures with respect to n messages from n signers into an aggregate signature, which can help communication equipments to save a lot of bandwidth and computing resources. Therefore, the certificateless aggregate signature (CLAS) scheme is particularly well suited to address secure routing authentication issues in resourceconstrained vehicular ad hoc networks. Unfortunately, most of the existing CLAS schemes have problems with security vulnerabilities or high computation and communication overheads. To avoid the above issues and better solve the secure routing authentication problem in vehicular ad hoc networks, we present a new CLAS scheme and give the formal security proof of our scheme under the CDH assumption in the random oracle model. We then evaluate the performance of our proposed CLAS scheme, and the results demonstrate that our proposal is more practical in resourceconstrained vehicular ad hoc networks.

Efficient provablysecure privacypreserving signaturebased key establishment protocol Abstract   Assuring the security and privacy of users in todayxe2x80x99s evergrowing digital communications is of prime significance. In a digital communication, in order to preserve the identities and confidential information of individuals, and more significantly, to prevent any unauthorized access and manipulation, the user and server need to establish a shared key. In recent years, a number of key establishment protocols have been put forward to keep the integrity, confidentiality, and anonymity of participants. Nonetheless, investigating the literature reveals the fact that the existing schemes cannot entirely assuage the desired security requirements. Therefore, in this paper, considering the computational efficiency, we propose a novel privacypreserving signaturebased key establishment protocol, which can guarantee subsequent secure communications of users and servers. To indicate that the proposed scheme can withstand the known attacks, we present a rigorous formal security proof and verification by utilization of two stateoftheart techniques, i.e., the random oracle model and ProVerif tool. Further, to show that the proposed protocol has proper performance, we compare our scheme with several recentlypublished schemes. The achieved results evince that the proposed scheme has a proper level of efficiency and is the best in terms of security provision.