QBUILD: Quantum-Resistant Blockchain Architecture for Secure and Transparent Construction Supply Chains in the Post-Quantum Era

The control of insecurity, transparency, and real-time tracking of assets are the urgent challenges of the construction supply chain because of the complex multi-stakeholder structure and the emergence of quantum computing threats. This paper applies a four-phase systematic approach to developing a Blockchain-based Construction Supply Chain (BCSC) framework, which includes: (1) architectural design of Hyperledger Fabric private blockchain with IoT-enabled real-time tracking, (2) smart contracts to process automated procurement, inventory, and payment, (3) quantum-resilient cryptography based on lattice-based encryption, approachable post-quantum secure digital signatures and (4) lightweight Federated Learning models to predictive analytics. The framework was tested with comparative performance analysis of the conventional blockchain solutions and confirmed by the real-world application of the same at SIL, a multinational construction company. The experiment outcomes prove significant improvements: security resiliency is 50% better, transactions latency decreases by 40% and traceability efficiency increases by 35% as compared to traditional blockchain-based supply chain solutions.