# On Blockchain-Enhanced Secure Data Storage and Sharing in Vehicular Edge Computing Networks
## 1 Introduction  
With a centralized approach, the traditional architecture of vehicular ad hoc networks (VANETs) has trouble overcoming the increasing complexity of applications for intelligent transportation systems (ITS) accompanied by difficulties in the provision of large volumes of data storage, trust management, and information security. Therefore, the concept of vehicular edge computing networks (VECNets) has evolved to be a promising paradigm that brings multiple opportunities to support computing, sharing, and massive data storage close to vehicles as a data provider by offering real-time transaction processing [1]. VECNets are defined as the integration of mobile edge computing with vehicular networks. It aims to decrease the overhead by placing computing resources closer to the network's end users. However, security and privacy issues are critical challenges for VECNets due to their risk of data leakage and single point of failure (SPoF) in the centralized server approach. Therefore, it is necessary to design a secure data management system in VECNets without an intermediary or a centralized approach. On the other hand, the concern of data privacy issues increases significantly in the context of data storage [2] and data sharing in a vehicular network because VECNets contain sensitive information of users, such as driving preferences, customer identities, and vehicle numbers. Therefore, the participant may be reluctant to store and share their data in the system due to the risk of various malicious activities that might jeopardize the system's security and participants' privacy for personal benefit. Ideally, all data are sentanonymously to overcome this issue as the data management environment is still untrusted. Therefore, the real identity of the user cannot be known by other users. However, even though it can solve the risk of a violation of privacy, it does not guarantee the data's reliability. Moreover, the user's interest will be reduced as the users do not benefit when they share their data or contribute to assessing the data's integrity from other users [3]. Therefore, the incentives mechanism is can be leveraged to encourage users or vehicles to store and share their data while assessing the credibility of data in VECNets. Since [PERSON] introduced Bitcoin [4], in the past ten years blockchain has gained much popularity as an emerging technology to provide better security on data sharing among many parties without an intermediary. Blockchain is considered an appropriate solution to address the privacy security issue [5], which can facilitate a secure, trusted, and decentralized intelligent transportation system [6]. In this sense, by looking at the blockchain's merits, the centralized server can be replaced by adopting a decentralized blockchain approach. In recent years, several works have been widely studying blockchain-based implementation in vehicular networks [7]. For instance, blockchain is utilized to form a decentralized trust management system in vehicular networks by allowing the neighboring vehicle to validate the received data using the Bayesian inference model [8] for preventing inappropriate data from a malicious vehicle [9]. Besides, consortium blockchain with joint Proof-of-Work (PoW) and practical byzantine fault tolerance (PBFT) consensus mechanism is used in order to achieve secure data sharing and storage system [10]. Further, by exploiting its smart contracts, blockchain efficiently manages a vehicle's reputation [11] and provide incentives based on the calculation of vehicle reputation values [12]. Motivated by the above developments, in this paper, a consortium blockchain and smart contracts are utilized to form distributed data storage and secure data sharing in VECNets. A consortium blockchain is a specific blockchain where the multiple nodes are preselected [13] and authorized to execute the consensus process and determine the generation of each block.