Post-Quantum Cryptographic Framework for Securing Critical Digital Public Infrastructure against Emerging Quantum Threats

Purpose: This study presents a comprehensive post-quantum cryptographic framework designed to secure Critical Digital Public Infrastructure (DPI) against emerging quantum computing threats. Methodology: As traditional cryptographic methods become increasingly vulnerable, the proposed framework integrates post-quantum algorithms, hybrid cryptographic models, and a multi-layered architecture to ensure long-term data protection. The system is evaluated using key performance metrics such as latency, throughput, energy consumption, overhead, key size, and security strength. Additionally, an algorithm selection strategy is implemented to identify optimal cryptographic techniques. Findings: Simulation results demonstrate that classical models offer better efficiency, while post-quantum approaches provide stronger security at the cost of higher resource usage. The hybrid model effectively balances these trade-offs, delivering improved security with moderate performance impact. Unique Contribution to Theory, Policy and Practice: Overall, the framework provides a scalable, adaptable, and future-ready solution for protecting critical infrastructure in a rapidly evolving digital and quantum landscape.