LAUSR

The advent of group-oriented communication applications has triggered research on secure group communication (SGC) in vehicular ad hoc networks (VANETs). Given this, some researchers worked in this area and proposed various schemes. However, these systems lacking the dynamic nature, and struggling with larger processing loads, enormous storage, increased communications, security, and privacy concerns. Further, with the increase in the size of VANET, it is challenging to manage processing loads and storage requirements of group controller (GC)-centric group key agreement (GKA). To address these drawbacks in existing VANET communications, we propose a blockchain IOTA sharding-based smart contract-centric GKA for SGC in large VANETs. In this scheme, we partition the main network into ${r}$ sharded subnetworks using blockchain sharding technique, with $G_{1}, G_{2}, G_{3},\ldots, G_{r}$ as smart contract (SC) instances generated by GC, G, which functions as Sub-GC (Sub-GC) to their respective shards. Under the Elliptic curve decision Diffie–Hellman (ECDDH) and group-Elliptic curve Diffie-Hellman (GECCDH) assumptions, the proposed protocol is proven to be secure. The suggested protocol outperforms the other protocols for secure communication in large VANETs, according to the performance analysis.