With the development of Intelligent Transportation Systems (ITS), Vehicular Ad hoc Networks (VANETs) have become a research hotspot in recent years. However, the vehicle communication system is vulnerable, resulting in threats to the privacy of users. This paper proposes a secure and efficient identity-based anonymous authentication scheme and uses pseudonyms to enhance the privacy protection of vehicle users. By improving the existing vehicle public key infrastructure and introducing Bloom filter to compress the Certificate Revocation List (CRL), the efficient pseudonym revocation scheme is then presented under the premise of ensuring user privacy. This scheme is able to perform batch pseudonym revocation and keep the pseudonym unlinkable. The security analysis shows that the proposed scheme is able to meet the security and privacy requirements in VANETs and CRL distribution.

The epoxy-acrylate (EA) was mixed with Ag-plated graphene (Ag-G), which was used as the conductive filler, to prepare the dual-curable electrical conductive adhesive (ECA). The characterization of Ag-G has been carried out by transmission electron microscope, X-ray diffraction, Raman spectrum, and X-ray photoelectron spectroscopy. Results showed that the Ag-G has been successfully prepared and the relative amount of Ag nanoparticles was 11.25 At%. The mechanical and conductive properties together with thermal stability of ECA have also been investigated. The shear strength reached to 4.67 MPa and the electrical conductivity of ECA reached to 0.41 S/cm when the content of conductive filler was 25 wt%, respectively. This content was regarded as the optimum. And, thermal analysis indicated that ECA exhibited better thermal stability than EA.

Privacy disclosure has become a key challenge in vehicular ad hoc networks (VANETs). Although IEEE, ERSI, etc. suggest that a pseudonym-based scheme is a solution, how to support pseudonym management and vehicle authentication is still an open issue. In this paper, a secure VANETs authentication scheme (PAS) is proposed, where software-defined network (SDN) is integrated as a suitable infrastructure to support anonymous authentication and pseudonym management, while removing the requirement for pseudonym certification in the dynamic VANETs environment. The security and performance analysis indicate that PAS is able protect the privacy of vehicles and has a high efficiency.

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