The Key Management System (KMS) is an important component in scaling up from link-to-link key generation to large key distribution networks. In this work we provide an overview of a KMS in the context of Quantum Key Distribution Networks (QKDN) and give a thorough summary of the functionality of a KMS in such an application. Beyond classical QKDNs, we discuss Post Quantum Cryptography (PQC) hybridization techniques at the KMS level. These methods add an additional layer of security against quantum computer driven attacks. We also discuss selected topics regarding the development, deployment and operation of components for such security infrastructure. In addition, relevant standards in the realm of Quantum Key Distribution (QKD) are outlined and analyzed. As some of the necessary interfaces have not been standardized, namely the interface between two KMS instances and the interface between the KMS and the Software Defined Network (SDN) Agent, we propose APIs for these two cases. The design of the interface between the KMS and QKD modules is discussed and, considering their resource constraints, a push mode for the ETSI GS QKD 004 standard is proposed. Finally, implementation details of a prototype KMS are outlined and trade-offs are discussed.
The Key Management System (KMS) is an important component in scaling up from link-to-link key generation to large key distribution networks. In this work we provide an overview of a KMS in the context of Quantum Key Distribution Networks (QKDN) and give a thorough summary of the functionality of a KMS in such an application. Beyond classical QKDNs, we discuss Post Quantum Cryptography (PQC) hybridization techniques at the KMS level. These methods add an additional layer of security against quantum computer driven attacks. We also discuss selected topics regarding the development, deployment and operation of components for such security infrastructure. In addition, relevant standards in the realm of Quantum Key Distribution (QKD) are outlined and analyzed. As some of the necessary interfaces have not been standardized, namely the interface between two KMS instances and the interface between the KMS and the Software Defined Network (SDN) Agent, we propose APIs for these two cases. The design of the interface between the KMS and QKD modules is discussed and, considering their resource constraints, a push mode for the ETSI GS QKD 004 standard is proposed. Finally, implementation details of a prototype KMS are outlined and trade-offs are discussed.
The European Quantum Communication Infrastructure (EuroQCI) initiative is fostering the deployment of national quantum key distribution (QKD) testbeds across the European Union. In this context, we report on the design, implementation, and evaluation of the Austrian testbed, with a particular focus on advances in key management and applicationlevel integration of QKD. First, we introduce a hybrid key management system (KMS) that combines QKD-derived keys in a decentralized architecture with post-quantum authenticated key exchange, enabling end-to-end hybrid keys while reducing trust assumptions in intermediate nodes. Second, we present three QKD-enabled applications: (i) a secure secret-sharing-based storage system leveraging QKD-protected share distribution, (ii) a QKD-integrated extension of Jitsi employing ETSI GS QKD 014 group keys to reduce overhead in multi-party communication, and (iii) a hybrid QKD/PQC WireGuard-based VPN enabling QKD-secured HSM backup operations without requiring modifications to proprietary HSM protocols. Finally, we describe the deployment of these solutions in a national network comprising a four-node metropolitan testbed and a 200 km long-distance link with trusted nodes, and provide performance measurements for both the network and the hybrid KMS. Together, these results demonstrate the feasibility of integrating QKD into heterogeneous applications and hybrid cryptographic infrastructures.
Key Management Systems (KMSs) are essential for secure and scalable Quantum Key Distribution (QKD) networks. For successful integration of QKD into existing security protocols, it is crucial that KMSs can reliably deliver keys with sufficiently low latency. Yet, the performance of practical implementations remains insufficiently characterized. We benchmarked the throughput and latency of the key-delivery interfaces of several commercial KMS solutions alongside an in-house developed system. Our evaluation reveals that the KMS performance degrades significantly under high-workload conditions, indicating that current designs require substantial optimization before they can support large-scale, high-demand QKD deployments.
Quantum Key Distribution (QKD) is one of the major cryptographic solutions to tackle the security threats associated to future computational advances, in particular those coming from quantum computing. At the most simple level, QKD can be seen as a highly secure source of symmetric secret keys in two separated places. Nonetheless, the lack of standardization and the strong requirements from the physical layer makes this technology very difficult to integrate in existing infrastructure.However, the success of QKD networks radically depends on the degree in which they can be adopted in the existing infrastructure, and it is a must that it happens via standard protocols and interfaces. The flexibility of novel network paradigms, like Software-Defined Networking (SDN), allows for a faster adoption of new concepts, hardware and services in telecommunications networks. This paradigm can be used for quantum communications, allowing for a fast and scalable deployment of quantum technologies and services in the telecommunications network to a degree that was simply impossible in previous schemes, where the different network devices and their connections should be modified, one by one, to create a quantum communications channel.This tutorial provides an introduction to existing QKD technologies and networks, followed by a descriptive explanation on how SDN principles can be utilized to abstract and integrate QKD systems as part of the network management. This will help to reduce the time-to-market for quantum technologies, and also will make quantum cryptography available as a service to be capitalized by the network operators.
Quantum Key Distribution (QKD) has progressed from a theoretical cryptographic concept to an emerging secure communication infrastructure technology. While early work focused on protocol security and physical-layer feasibility, current research increasingly addresses scalable network deployment, hardware acceleration, and integration with classical communication systems. As QKD expands from point-to-point links to metropolitan, backbone, and hybrid satellite–terrestrial networks, new engineering challenges arise in topology design, entropy generation, real-time key distillation, and multi-vendor interoperability. This survey provides an infrastructure-oriented review of QKD networks, examining architectural models, quantum randomness as a root of trust, FPGA and system-on-chip (SoC) based acceleration techniques, and programmable control-plane integration. Key management system architectures and standardized interfaces are analyzed to highlight their roles in enabling scalable, interoperable deployments. The paper also synthesizes major standardization efforts and deployment initiatives shaping carrier-grade QKD infrastructures. Finally, open engineering challenges, including scalability, control-plane integration, certification harmonization, and hybridization with post-quantum cryptography, are identified, positioning QKD as a foundational component of next-generation secure communication systems.
This paper introduces several hybrid protocols based on Quantum Key Distribution (QKD) and Post-Quantum Cryptography (PQC) implemented in the OpenQKD testbed Berlin to improve the security of the QKD nodes. Instead of following the ETSI QKD014 standard of a key management system based on classical security, i.e., RSA authentication and ECC encryption, we implemented a quantum-secure Key Management System based on PQC Key Encapsulation and Signature algorithms. The hardware and the software components of the QKD network authenticate themselves using a PQC trust chain and Pre-Shared Secrets, wherever supported. The communication between QKD nodes, as for the encryption key forwarding process, is hardened by Post-Quantum Cryptography to prevent cryptographic key exposure on intermediate network nodes. Using the two implemented key exchange processes, based on QKD and PQC, applications are able to request any kind of encryption key from the Key Management System and combine them arbitrarily to compute more reliable cryptographic keys.
ABSTRACT Quantum cryptography has increasingly attracted interest from both industry and academia for its potential in real‐world applications. With advancements in quantum electronics, practical quantum devices are now commercially available and poised for broader adoption. Quantum key distribution (QKD) leverages fundamental principles of quantum mechanics to ensure secure communication, whereas quantum key distribution networks (QKDN) serve as the foundational infrastructure for deploying and scaling these secure systems. This paper examines the design methodologies specific to QKD within QKDN, emphasising both the conceptual framework and the practical challenges inherent in the field. In the pursuit of developing robust QKDN design, several key obstacles, related to the foundational QKD technology, must be addressed. These include decoherence, which affects the stability of quantum states and reduces key generation rates; latency, which disrupts synchronisation throughout the QKD network; and intrinsic quantum noise, an inherent property of quantum systems that primarily limits the overall performance of the QKD network. In addition, the limited communication ranges and the requirement for highly specialised hardware complicate the practical deployment of these networks. This work serves as an introductory guide for researchers entering the field, providing an overview of the fundamental principles of QKD network design and the distinctive routing characteristics inherent to such systems. It outlines the essential steps and considerations for building efficient and resilient QKDN infrastructures, including a discussion of the foundational principles, protocols and existing challenges.