Integrating Classical and Quantum PUF with QKD for Secure IoT Networks

The increasing adoption of large-scale IoT systems introduces significant challenges for secure communication. At the same time, advances in quantum computing threaten the security of classical cryptographic schemes, motivating the need for lightweight and quantum-resilient solutions. Quantum Key Distribution (QKD) offers information-theoretic security, but requires an authenticated classical channel, typically relying on pre-shared keys, which limits scalability in heterogeneous IoT environments. Existing approaches either assume unrealistic quantum capabilities at the IoT level or rely on stored secrets and centralized infrastructures. In this work, we propose a hierarchical architecture that combines Quantum Physical Unclonable Functions (QPUFs), QKD, and classical PUFs to enable secure key establishment across IoT subnetworks without pre-shared keys or long-term secret storage. The approach leverages quantum-enabled gateways as trust anchors, while keeping IoT devices lightweight and purely classical. We implement the QPUF on real quantum hardware and evaluate its performance in terms of stability, uniqueness, and uniformity. The results indicate that the proposed design provides reliable and distinctive responses, supporting its use as a hardware-rooted trust anchor and demonstrating the feasibility of integrating quantum security mechanisms into practical IoT systems.