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.
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.
Quantum key distribution (QKD) is a technology that can resist the threat of quantum computers to existing conventional cryptographic protocols. However, due to the stringent requirements of the quantum key generation environment, the generated quantum keys are considered valuable, and the slow key generation rate conflicts with the high-speed data transmission in traditional optical networks. In this paper, for the QKD network with a trusted relay, which is mainly based on point-to-point quantum keys and has complex changes in network resources, we aim to allocate resources reasonably for data packet distribution. Firstly, we formulate a linear programming constraint model for the key resource allocation (KRA) problem based on the time-slot scheduling. Secondly, we propose a new scheduling scheme based on the graded key security requirements (GKSR) and a new micro-log key storage algorithm for effective storage and management of key resources. Finally, we propose a key resource consumption (KRC) routing optimization algorithm to properly allocate time slots, routes, and key resources. Simulation results show that the proposed scheme significantly improves the key distribution success rate and key resource utilization rate, among others.
With the development of quantum computing and computer science, the risk of traditional cryptographic algorithms being cracked is increasing. Therefore, quantum key distribution (QKD) technology based on quantum physical properties has been developed to ensure the security of information communication. Large-scale QKD networks can be built using trusted relay technology, but the hops encryption and decryption process of trusted relay will consume extra keys, which makes it particularly important to choose a reasonable path to reduce the consumption of extra keys during key distribution. The existing routing algorithms mainly focus on the number of remaining keys and hops, but ignore the congestion information of the network, resulting in a high key exchange failure rate and an increase in key consumption. In view of this background, we propose a load balancing routing (LBR) algorithm, which can realize congestion control in QKD network by dynamically detecting link state with SDN controller. Simulation results show that LBR improves key request success rate by more than 10% and key utilization efficiency by about 5% compared with existing methods.
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 unconditional peer-to-peer security based on the principles of quantum physics. By utilizing relay nodes, the security of QKD can be extended over longer distances. However, the introduction of relay nodes brings both security and communication success rates issues. To tackle those issues we propose an enhanced multi-path scheme. The key features of our proposal are as follows: 1. By taking the reliability of relay nodes as one of the algorithm inputs,making the scheme more suitable for partially trusted QKD (PTQKD) networks. 2. By using Multi-Segment Multi-Path approach increases the difficulty for attackers to obtain complete key information and improves the security of PTQKD. 3. The adaptive routing algorithm generates a sufficient number of diverse paths based on node contribution rate, key freshness, and reliability. We conducted a theoretical analysis of the algorithm,and simulation results on PTQKD demonstrate that our method outperforms traditional QKD methods in terms of security and transmission success rate. This advancement has the potential to enhance the adoption of QKD networks.
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) 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.