A Blockchain-Based Searchable Public-Key Encryption With Forward and Backward Privacy for Cloud-Assisted Vehicular Social Networks

As the integration of the Internet of Vehicles and social networks, vehicular social networks (VSN) not only improves the efficiency and reliability of vehicular communication environment, but also provide more comprehensive social services for users. However, with the emergence of advanced communication and computing technologies, more and more data can be fast and conveniently collected from heterogeneous devices, and VSN has to meet new security challenges such as data security and privacy protection. Searchable encryption (SE) as a promising cryptographic primitive is devoted to data confidentiality without sacrificing data searchability. However, most existing schemes are vulnerable to the adaptive leakage-exploiting attacks or can not meet the efficiency requirements of practical applications, especially the searchable public-key encryption schemes (SPE). To achieve secure and efficient keyword search in VSN, we design a new blockchain-based searchable public-key encryption scheme with forward and backward privacy (BSPEFB). BSPEFB is a decentralized searchable public-key encryption scheme since the central search cloud server is replaced by the smart contract. Meanwhile, BSPEFB supports forward and backward privacy to achieve privacy protection. Finally, we implement a prototype of our basic construction and demonstrate the practicability of the proposed scheme in applications.

I. Introduction

Vehicular social network as an emerging field is an integration of social networks and the vehicular ad hoc networks [1]. It inherits the relevant features and concepts from both the social networks description relationships and the vehicular networks for communication among vehicle users. With the development of communication and computing technologies, especially 5 G technology and cloud computing, more and more data for VSN can be fast and conveniently collected from heterogeneous devices, including Infrastructure, vehicle users, On-Board Units, passengers. Gartner predicts that by 2020 the number of connected vehicles on the road will be 250 million and the data volumes will get into 300 thousand EB [2]. Thanks to the progress of cloud computing technology, such a huge amount of data can be managed and utilized effectively. The classical cloud-assisted VSN framework is shown in Fig. 1. However, data outsourced to the cloud generally contain some sensitive information [3]–[9], i.e., identities of drivers, the interest of passengers, the location of vehicles, etc. Therefore, security mechanisms must be designed to address security and privacy issues.