Abstract With quantum computing posing a threat to traditional encryption, quantum key distribution (QKD) networks have become crucial for achieving information-theoretic secure communication. However, current QKD networks generally face a scarcity of high-security key resources. This scarcity stems not only from the distance attenuation limitations of physical channels but also from the lack of dynamic awareness of service security requirements in existing routing strategies, leading to the excessive consumption of critical key resources by low security level (LSL) services. To address this, this paper proposes a security-aware key fusion multi-path routing scheme: First, a quantum exclusive-or (XOR) key fusion (Q-XOR-KF) mechanism is designed to dynamically fuse redundant LSL and medium security level (MSL) keys into a high security level (HSL) key through multi-layer XOR operations. Second, a security-aware routing algorithm (S-MPRA) that works in conjunction with a software-defined network (SDN) controller is proposed. This algorithm introduces a fusion overhead-aware link cost function, which can intelligently calculate the optimal path based on the real-time security level and rate requirements of the service, and trigger key fusion operations when necessary, achieving deep collaborative optimization of routing decisions and key resource management. Simulation results show that the proposed scheme significantly outperforms existing methods in terms of request success rate, high-security request success rate, and effective key rate, providing a new approach for building efficient and robust quantum-safe networks.
Abstract With quantum computing posing a threat to traditional encryption, quantum key distribution (QKD) networks have become crucial for achieving information-theoretic secure communication. However, current QKD networks generally face a scarcity of high-security key resources. This scarcity stems not only from the distance attenuation limitations of physical channels but also from the lack of dynamic awareness of service security requirements in existing routing strategies, leading to the excessive consumption of critical key resources by low security level (LSL) services. To address this, this paper proposes a security-aware key fusion multi-path routing scheme: First, a quantum exclusive-or (XOR) key fusion (Q-XOR-KF) mechanism is designed to dynamically fuse redundant LSL and medium security level (MSL) keys into a high security level (HSL) key through multi-layer XOR operations. Second, a security-aware routing algorithm (S-MPRA) that works in conjunction with a software-defined network (SDN) controller is proposed. This algorithm introduces a fusion overhead-aware link cost function, which can intelligently calculate the optimal path based on the real-time security level and rate requirements of the service, and trigger key fusion operations when necessary, achieving deep collaborative optimization of routing decisions and key resource management. Simulation results show that the proposed scheme significantly outperforms existing methods in terms of request success rate, high-security request success rate, and effective key rate, providing a new approach for building efficient and robust quantum-safe networks.
Quantum key distribution (QKD) provides information-theoretic security based on quantum mechanics, and as quantum key distribution becomes increasingly practical, questions of how to employ it effectively over largescale networks and large distances becomes increasingly important. In this work, we investigate the B92 entanglement based QKD protocol and a five-layer QKD network architecture consisting of trusted relay nodes. Previous research seldom focused on the ground routing mechanism of QKD networks in detail. Since no intersecting links are beneficial to reducing the key consumption rate and improving link security, combined with the core idea of reducing the number of link relay hops, we propose a minimum path cost multi-path routing algorithm for no intersecting links in quantum key distribution networks. By analyzing the security of the link, we effectively reduce the number of relay nodes and the number of relay links that pass through and give priority to the routing scheme with the minimum number of hops in the number of relay hops, which avoids the congestion and waste caused by the existence of interleaved multi-path in traditional multi-path routing. Meanwhile, the scheme effectively improves the quality of service index, avoids the generation and consumption of redundant keys, and reduces the waste of quantum key resources.
Quantum Key Distribution (QKD) networks enable unconditionally secure key exchange using quantum mechanical principles. However, routing cryptographic keys across multi-hop quantum networks introduces challenges unique to quantum communication. This survey analyzes and classifies 26 routing strategies proposed between 2013 and 2024 for terrestrial, satellite, and hybrid QKD infrastructures. Dynamic, key-aware routing algorithms have been shown to reduce service rejection rates by 25-40% compared to static shortest-path methods by incorporating real-time key pool availability and link error rates. Multi-path strategies improve resilience against trusted-node compromise by distributing keys across disjoint routes, albeit with an increase in key consumption of 30-60%. SDN-based orchestration frameworks emerge as essential enablers of flexible, QoS-aware routing for hybrid networks integrating terrestrial fibers and intermittent satellite links. Critical research directions include reducing dependence on trusted nodes through quantum repeaters or post-quantum cryptography, developing standardized key management interfaces for interoperability, and adopting AI-driven predictive routing for adapting to fluctuating network states. This comprehensive synthesis of routing algorithms, performance trade-offs, and unresolved issues offers practical guidance for engineering secure, adaptable, and large-scale QKD networks capable of meeting real-world deployment demands.
With quantum computing advancing, traditional encryption risks cracking, making quantum key distribution (QKD) crucial for its quantum-physics-based unconditional security. Large-scale QKD networks face high key consumption, uneven allocation, and reduced long-distance generation rates. This paper proposes MTSA, a time slot allocation-based multi-path routing scheme using linear programming and SDN for load balancing, with a two-level cache queue and optimized polling algorithm. Simulations on NSFNET/USNET show MTSA boosts key utilization by 15.565% and distribution success rate by 12.534%, optimizing QKD network performance.
The ability to protect information has always played an important role in the evolution of civilizations, and even in the history of mankind as a whole. Safe and reliable communications have become an essential component of people’s lives in the era of modern digital technologies, when all spheres and areas of activity, from defense and government to business and social communications, are unthinkable without real-time data exchange. Classical methods of cryptographic protection have long been used to ensure the security of data transmission, but with the explosive growth in computing power and the emerging development of quantum computers, many traditional solutions have become vulnerable. Quantum Key Distribution (QKD) is a popular research area at the moment, due to its use of the laws of quantum mechanics, and thus it is possible to provide a completely secure level of encryption. But traditional quantum communication protocols have their limitations, including low key generation rates, scalability problems in large networks, and vulnerabilities to various forms of cyberattacks in the network layer. Therefore, in this work we propose a new adaptive quantum key distribution algorithm using software-defined networking (SDN) technology. The main idea of the proposed approach is to introduce some level of redundancy in the key generation stage, which increases the throughput, robustness, and adaptability of multi-node quantum networks. In addition, the SDN control layer allows dynamic routing and resource management and quick response to changes in the network state, making the system more resistant to denial-of-service and eavesdropping attacks. Evaluating our solution in comparison with BB84, we show that the new algorithm provides better performance without losing its security level, making the work a step towards creating a working quantum-secure communication system.
Hybrid-trusted Quantum Key Distribution (QKD) networks face unique security challenges due to semi-trusted nodes. These nodes may introduce security threats such as man-in-the-middle attacks and key storage side-channel leakage. With the increasing complexity of QKD network architectures and expanding application scenarios, substantial divergences have emerged between user requirements for communication duration and cryptographic security demands. To address security challenges in hybrid-trusted QKD environments and provide differentiated services for users with varying requirements, this paper proposes a Service Requirement-based Hybrid-Trusted QKD Network (SRHT-QKDN) routing scheme. We propose a time-slot allocation model for QKD that employs time-slot resources as substitutes for key-generation resources in resource allocation processes. For sustained key distribution required by prolonged communications, the scheme implements two distinct time slot allocation algorithms: continuous-consistent and discrete-inconsistent allocation, enabling periodic quantum key updates. Concurrently, QKD requests are classified into three security levels, with corresponding routing strategies developed for each tier to achieve security service differentiation while maintaining routing success rates. Simulations conducted under four distinct operational conditions demonstrate that the SRHT-QKDN routing scheme not only effectively fulfills key continuity requirements but also achieves optimal overall performance in request success rate and security assurance, outperforming two benchmark routing schemes.
Quantum key distribution (QKD), a key application of quantum information technology and “one-time pad” (OTP) encryption, enables secure key exchange with information-theoretic security, meaning its security is grounded in the laws of physics rather than computational assumptions. However, in QKD networks, achieving long-distance communication often requires trusted relays to mitigate channel losses. This reliance introduces significant challenges, including vulnerabilities to compromised relays and the high costs of infrastructure, which hinder widespread deployment. To address these limitations, we propose a zero-trust spatiotemporal diversification framework for multipath–multi-key distribution. The proposed approach enhances the security of end-to-end key distribution by dynamically shuffling key exchange routes, enabling secure multipath key distribution. Furthermore, it incorporates a dynamic adaptive path recovery mechanism that leverages a recursive penalty model to identify and exclude suspicious or compromised relay nodes. To validate this framework, we conducted extensive simulations and compared its performance against established multipath QKD methods. The results demonstrate that the proposed approach achieves a 97.22% lower attack success rate with 20% attacker pervasiveness and a 91.42% reduction in the attack success rate for single key transmission. The total security percentage improves by 35% under 20% attacker pervasiveness, and security enhancement reaches 79.6% when increasing QKD pairs. Additionally, the proposed scheme exhibits an 86.04% improvement in defense against interception and nearly doubles the key distribution success rate compared to traditional methods. The results demonstrate that the proposed approach significantly improves both security robustness and efficiency, underscoring its potential to advance the practical deployment of QKD networks.