With the rise of intelligent transportation, various mobile value-added services can be provided by the service provider (SP) in the Internet of Vehicles (IoV). To guarantee the dependability of services, it is essential to implement a mutual authentication protocol between the vehicles and the SP. Existing mutual authentication protocols to secure the communication between the SP and the vehicle raise challenges such as providing fine-grained forward security for the SP and achieving backward security for the vehicle. To handle these challenges, this paper proposes a conditional privacy-preserving mutual authentication protocol featured with fine-grained forward security and backward security for IoV, which can be implemented via two building blocks we have constructed. Specifically, we present a new puncturable signature (PS) scheme without false-positive probability and the update of the public key as well as the first proxy re-signature scheme with parallel key-insulation (PKI-PRS). What’s more, both the proposed PKI-PRS and PS still have interest beyond this protocol. Then, an anonymous mutual authentication protocol with resistance to key leakage is constructed by incorporating the above signature schemes. The proposed protocol not only provides fine-grained forward security for the SP, but also ensures forward security as well as backward security for the vehicles. Besides, the approach to achieving anonymous authentication can efficiently provide conditional privacy-preserving for the vehicles. With the support of the random oracle model and experimental simulations, the formal security proof and the superiority of the proposed protocol is explicitly given.

Existing proxy re-encryption (PRE) schemes to secure cloud data sharing raise challenges such as supporting the heterogeneous system efficiently and achieving the unbounded feature. To address this problem, we proposed a fast and secure unbounded cross-domain proxy re-encryption scheme, named FABRIC, which enables the delegator to authorize the semi-trusted cloud server to convert one ciphertext of an identity-based encryption (IBE) scheme to another ciphertext of an attribute-based encryption (ABE) scheme. As the first scheme to achieve the feature mentioned above, FABRIC not only enjoys constant computation overhead in the encryption, decryption, and re-encryption phases when the quantity of attributes increases, but is also unbounded such that the new attributes or roles could be adopted into the system anytime. Furthermore, FABRIC achieves adaptive security under the decisional linear assumption (DLIN). Eventually, detailed theoretical and experimental analysis proved that FABRIC enjoys excellent performance in efficiency and practicality in the cloud computing scenario.