EBAS: An Efficient Blockchain-Based Authentication Scheme for Secure Communication in Vehicular Ad Hoc Network

A vehicular ad hoc network (VANET) is essential in building an intelligent transportation system that optimizes traffic conditions and makes traffic information conveniently accessible. However, malicious vehicles may disrupt the traffic order via propagating forged traffic/road information. Therefore, using digital certificates based on cryptography, some existing authentication schemes were proposed to manage vehicles' identities. At first glance, these schemes can effectively identify malicious vehicles. However, these schemes require more computation and storage resources to maintain certificates. This is because the data storage of the database increases in a near-linear trend as the number of certificates grows. In this paper, we propose an efficient blockchain-based authentication scheme for secure communication in VANET (EBAS) to address the aforementioned issues. In EBAS, the regional trusted authority (RTA) receives traffic messages uploaded by the vehicle, together with transactions constructed via the unspent transaction output (UTXO) model. The verifier checks the legitimacy of the single input contained in the uploaded transaction to verify the legitimacy of the message sender's identity. In terms of privacy preservation, a asymmetric key encryption technique, elliptic curve cryptography (ECC), is applied for constructing the transaction pseudonym, and users participate in the authentication process anonymously. In addition, our scheme guarantees the scalability of EBAS by proposing a transaction update mechanism, which can keep data storage at a stable level rather than near-linear growth. Under the simulation, the retrieving overhead remains at approximately 0.32 ms while the storage cost is stable at around 32.7 M for the blockchain state database. In terms of authentication efficiency, the average overhead of the proposed scheme is around 0.942 ms, which outperforms the existing schemes.