Integrating post-quantum cryptography (PQC) with quantum key distribution (QKD): performance, security, and practical challenges

The convergence of post-quantum cryptography (PQC) and quantum key distribution (QKD) represents a compelling strategy for building future-proof secure communication systems. While PQC relies on mathematical problems resistant to quantum attacks, QKD provides information-theoretic security based on the laws of quantum mechanics. However, integrating these two paradigms introduces numerous challenges related to authentication, key management, performance asymmetries, and protocol standardization. This paper explores these issues in detail and further introduces the role of quantum random number generators (QRNGs) as a foundational element to support both PQC and QKD systems. We discuss how QRNGs can be integrated into hardware and software-based cryptographic systems to provide high-throughput, side-channel-resistant entropy, and propose architectures that leverage PQC for scalable authentication and QKD for secure key distribution. Our goal is to present a layered security model that harnesses the strengths of each component, while identifying research gaps and integration challenges for real-world deployment.