Recent advances in quantum-secure communication have highlighted the value of hybrid schemes that combine Quantum Key Distribution (QKD) with Post-Quantum Cryptography (PQC). Yet most existing hybrid designs omit realistic finite-key effects on QKD key rates and do not specify how to maintain security when both QKD and PQC primitives leak information through side-channels. These gaps limit the applicability of hybrid systems in practical, deployed networks. In this work, we advance a recently proposed hybrid QKD-PQC system by integrating tight finite-key security to the QKD primitive and improving the design for better scalability. This hybrid system employs an information-theoretically secure instruction sequence that determines the configurations of different primitives and thus ensures message confidentiality even when both the QKD and the PQC primitives are compromised. The novelty in our work lies in the implementation of the tightest finite-key security to date for the BBM92 protocol and the design improvements in the primitives of the hybrid system that ensure the processing time scales linearly with the size of secret instructions.
Journal reference
IEEE International Conference on Quantum Communications, Networking, and Computing (QCNC) 2026 Kobe, Japan
Recent advances in quantum-secure communication have highlighted the value of hybrid schemes that combine Quantum Key Distribution (QKD) with Post-Quantum Cryptography (PQC). Yet most existing hybrid designs omit realistic finite-key effects on QKD key rates and do not specify how to maintain security when both QKD and PQC primitives leak information through side-channels. These gaps limit the applicability of hybrid systems in practical, deployed networks. In this work, we advance a recently proposed hybrid QKD-PQC system by integrating tight finite-key security to the QKD primitive and improving the design for better scalability. This hybrid system employs an information-theoretically secure instruction sequence that determines the configurations of different primitives and thus ensures message confidentiality even when both the QKD and the PQC primitives are compromised. The novelty in our work lies in the implementation of the tightest finite-key security to date for the BBM92 protocol and the design improvements in the primitives of the hybrid system that ensure the processing time scales linearly with the size of secret instructions.
Quantum computing is posing a serious risk to classical cryptographic tools such as RSA and ECC as sophisticated quantum algorithms are able to crack their mathematical foundation in a time bound that is a a polynomial in the number of repetitions. In this paper, we will describe the process of integrating Post-Quantum Cryptography (PQC) and Quantum Key Distribution (QKD) into a hybrid approach to secure communications in the post-quantum world. The suggested methodology is a combination of the computational efficiency and scalability of PQC and the information-theoretic security and eavesdropping detection abilities of QKD. Simulation observations indicate that PQC-only systems are both faster in generating keys and scalable, but do not have a strong eavesdropping detection. On the other hand, non-conditional security is only a feature of systems based on QKD, but it is also highly overhead and slows down key rate. The hybrid PQC-Q KD model provides a balanced performance, high resilience, high authentication, high confidentiality, and realistic deployability. On balance, this discussion demonstrates that the hybrid approach is better than standalone methods and can provide a strong solution to protect against new quantum threats. The large-scale network protocol can be optimized, resources and further integration with other emerging technologies, such as 5G/6G, IoT or cloud computing, can be directed in future research.
Once a cryptographically relevant quantum computer is built, confidential information that is communicated today can be decrypted and exposed. Key exchange methods currently used can then be broken and the key used to protect the data can be recovered. Depending on the duration for which information needs to remain confidential, quantum-safe solutions have to be used now to protect data transmitted today. In this paper, we review recent advances in integrating the combination of two different quantum-safe solutions, Quantum Key Distribution (QKD) and Post-Quantum Cryptography (PQC), in existing protocols. We also combine classical cryptography, PQC and QKD to securely exchange a key that remains secure even if only one of the three key exchange methods is secure. This is one of the first steps to update existing communication methods such that they remain secure even if only one of PQC, QKD or classical cryptography is secure.
Quantum Key Distribution (QKD) provides information-theoretic security based on quantum mechanics, but its practical deployment is limited by its reliance on classical infrastructure and inability to operate as a standalone solution.Recent research emphasizes hybrid approaches that combine QKD with post-quantum cryptography (PQC) to achieve practical and robust security.This paper presents a hybrid key distribution model integrating QKD with the postquantum key encapsulation mechanism.The two independently generated keys are combined to derive a unified shared secret, enhancing resilience against both classical and quantum adversaries.The system is implemented using a simulated quantum environment, enabling the emulation of quantum communication over classical networks.The proposed approach is validated through a secure image transmission use case, demonstrating the correctness of the hybrid key exchange.The results highlight the feasibility of hybrid classical-quantum cryptographic systems as a practical step toward secure communication in emerging quantum network infrastructures.
Quantum resistance is vital for emerging cryptographic systems as quantum technologies continue to advance towards large-scale, fault-tolerant quantum computers. Resistance may be offered by quantum key distribution (QKD), which provides information-theoretic security using quantum states of photons, but may be limited by transmission loss at long distances. An alternative approach uses classical means and is conjectured to be resistant to quantum attacks, so-called post-quantum cryptography (PQC), but it is yet to be rigorously proven, and its current implementations are computationally expensive. To overcome the security and performance challenges present in each, here we develop hybrid protocols by which QKD and PQC inter-operate within a joint quantum-classical network. In particular, we consider different hybrid designs that may offer enhanced speed and/or security over the individual performance of either approach. Furthermore, we present a method for analyzing the security of hybrid protocols in key distribution networks. Our hybrid approach paves the way for joint quantum-classical communication networks, which leverage the advantages of both QKD and PQC and can be tailored to the requirements of various practical networks.
The rapid advancement of quantum technologies calls for the design and deployment of quantum-safe cryptographic protocols and communication networks. There are two primary approaches to achieving quantum-resistant security: quantum key distribution (QKD) and post-quantum cryptography (PQC). While each offers unique advantages, both have drawbacks in practical implementation. In this work, we introduce the pros and cons of these protocols and explore how they can be combined to achieve a higher level of security and/or improved performance in key distribution. We hope our discussion inspires further research into the design of hybrid cryptographic protocols for quantum-classical communication networks.
Quantum cryptography has emerged as a revolutionary technology for ensuring secure communication in the era of quantum computing. While existing research primarily focuses on theoretical frameworks and small-scale experimental setups, significant challenges remain in practical implementation, scalability, and security vulnerabilities. This study aims to bridge the gap between theory and real-world deployment by developing robust quantum cryptographic protocols that address key challenges such as noise management, side-channel attacks, and Trojan horse attacks. Additionally, we propose an optimized quantum key distribution (QKD) mechanism that ensures secure communication over long distances under realistic conditions. Our research integrates post-quantum cryptography with quantum cryptographic techniques to provide a hybrid security model that is resilient against both classical and quantum computing threats. By leveraging commercially available quantum hardware and advanced randomness extraction methods, this study contributes to the development of scalable, secure, and efficient quantum communication networks. The findings of this research will play a crucial role in advancing secure digital communication systems and fortifying data security in the post-quantum era.