Secure and Scalable Blockchain-Enabled 5G VehicularNetworks Using Federated Trust-Aware Sharding andCross-Shard Authentication

The rapid proliferation of fifth-generation (5G) vehicular networks requires massive connectivityand ultra-low-latency for intelligent transportation systems. While blockchain technologyprovides a promising decentralized foundation for data integrity and access control, existing vehicularblockchain frameworks remain limited in term of scalability and lack of integrated securitymechanisms. In particular, heuristic sharding approaches such as Determinantal Point Process(DPP)-based partitioning improve throughput but ignore the trustworthiness of participatingnodes and the security of cross-shard transactions. This paper proposes a Federated Trust-AwareDeterminantal Point Process (FT-DPP) framework combined with a Cross-Shard Secure TransactionChannel (CS-STC) to achieve scalable and security-preserving consensus in 5G vehicularblockchains. The proposed FT–DPP integrates trust, communication quality, and transactionload into the sharding kernel, while a Proof-of-Trust (PoT) consensus assigns voting power accordingto node reputation. The CS–STC validates inter-shard transactions through zero-knowledgeproofs (ZKP) bound to Merkle roots. Simulation and theoretical analysis confirmed improvedscalability, latency, and resistance to collusion compared with existing DPP-based and clusteringschemes. Comprehensive simulations demonstrated that the proposed model improves shard loadbalance by up to 28% and reduces overall consensus delay by 20–25% compared with DPP-basedand K-means benchmarks. Moreover, FT-DPP effectively lowers the attack success probabilityto below 5%, validating its robustness against Sybil and cross-shard spoofing attacks. The resultsindicated that integrating trust management with scalable sharding can provide a unified foundationfor secure, efficient, and trustworthy 5G-enabled vehicular blockchains. The novelty ofthis work lies in integrating federated trust directly into probabilistic sharding kernel, achievingsimultaneous scalability and security—two objectives which are traditionally in conflict invehicular blockchains.