A Quantum-Resilient Sharded Blockchain Framework for Secure V2X and Federated Learning in Intelligent Transportation Systems

The emergence of large-scale quantum computers threatens the security of classical public-key cryptosystems, making it essential to adopt post-quantum (PQ) security in Intelligent Transportation Systems (ITS). We introduce a framework that blends quantum-resilient cryptographic primitives with a sharded blockchain architecture. Each shard maintains a local ledger for its vehicle group, enabling real-time transactions and efficient certificate management without overloading any single chain. A lightweight global chain periodically anchors all shards, preserving system-wide consistency and blocking malicious revocations. Vehicles register or revoke PQ credentials via a lightweight Proof-of-Stake consensus, while roadside units (RSUs) handle signature verification to offload on-board computation. We further demonstrate practicality through a federated-learning case study in which vehicles exchange signed model updates over the same secure channel. SUMO/TraCI simulations with 2 000 vehicles and 10 shards show that despite PQ overhead the system sustains near real-time delays and high throughput. The framework thus offers a decentralized, quantum-resilient solution for secure Vehicle-to-Everything communications in next-generation ITS.