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IEEE International Conference on Advanced Networks and Telecommunications Systems

Security and Hop-Aware Shared Path Protection Scheme in Hybrid-Relay QKD Optical Networks

Xue Hu, Hong Chen, Weidong Shao, Vimal Bhatia, Suman Palrecha, Bowen Chen

Published Dec 15, 2025• 0 citations
Publisher

Abstract

In quantum key distribution (QKD) networks, the quantum service channel (QSCh) is highly sensitive to link failures, as any interruption in the quantum channel can immediately halt key generation, and hence the transmission of secured data across optical networks. Hence, robust protection mechanisms are essential to ensure continuous secure key distribution. However, conventional protection approaches, such as dedicated protection and fixed-path routing, often suffer from low resource efficiency and poor adaptability to heterogeneous relay environments. To ensure both survivability and efficient resource allocation in QKD based optical networks, we propose a shared path protection scheme based on hybrid relays. In the proposed approach, K-candidate paths are computed for both the traditional data channel (TDCh) and QSCh, and the working path is selected using a weighted metric that considers both the hop-count and the security degree. To enhance resilience, the shared protection paths are established, allowing multiple backup paths to reuse network resources for connection requests. A connection request is accepted only if both the working and the protection paths are successfully reserved, thereby ensuring strong protection. The system incorporates joint allocation of wavelength and time-slot, and introduces a protection threshold to support shared use of backup resources. Simulation results show that the proposed method achieves lower blocking probability, while maintaining high wavelength and time-slot efficiency compared to the baseline methods in different networks.

DOI
10.1109/ants66931.2025.11429745

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In quantum key distribution (QKD) networks, the quantum service channel (QSCh) is highly sensitive to link failures, as any interruption in the quantum channel can immediately halt key generation, and hence the transmission of secured data across optical networks. Hence, robust protection mechanisms are essential to ensure continuous secure key distribution. However, conventional protection approaches, such as dedicated protection and fixed-path routing, often suffer from low resource efficiency and poor adaptability to heterogeneous relay environments. To ensure both survivability and efficient resource allocation in QKD based optical networks, we propose a shared path protection scheme based on hybrid relays. In the proposed approach, K-candidate paths are computed for both the traditional data channel (TDCh) and QSCh, and the working path is selected using a weighted metric that considers both the hop-count and the security degree. To enhance resilience, the shared protection paths are established, allowing multiple backup paths to reuse network resources for connection requests. A connection request is accepted only if both the working and the protection paths are successfully reserved, thereby ensuring strong protection. The system incorporates joint allocation of wavelength and time-slot, and introduces a protection threshold to support shared use of backup resources. Simulation results show that the proposed method achieves lower blocking probability, while maintaining high wavelength and time-slot efficiency compared to the baseline methods in different networks.
Abstract Quantum key distribution (QKD) optical networks can provide more secure communications. However, with the increase of the QKD path requests and key updates, network blocking problems will become severe. The blocking problems in the network can become more severe because each fiber link has limited resources (such as wavelengths and time slots). In addition, QKD optical networks are also affected by external disturbances such as data interception and eavesdropping, resulting in inefficient network communication. In this paper, we exploit the idea of protection path to enhance the anti-interference ability of QKD optical network. By introducing the concept of security metric, we propose a routing wavelength and time slot allocation algorithm (RWTA) based on protection path, which can lessen the blocking problem of QKD optical network. According to simulation analysis, the security-metric-based RWTA algorithm (SM-RWTA) proposed in this paper can substantially improve the success rate of security key (SK) update and significantly reduce the blocking rate of the network. It can also improve the utilization rate of resources such as wavelengths and time slots. Compared with the non-security-metric-based RWTA algorithm (NSM-RWTA), our algorithm is robust and can enhance the anti-interference ability and security of QKD optical networks.
Optical network security is attracting increasing research attention, as loss of confidentiality of data transferred through an optical network could impact a huge number of users and services. Data encryption is an effective way to enhance optical network security. In particular, QKD is being investigated as a secure mechanism to provide keys for data encryption at the endpoints of an optical network. In a QKD-enabled optical network, apart from TDChs, two additional channels, called QSChs and PIChs, are required to support secure key synchronization. How to allocate network resources to QSChs, PIChs, and TDChs is emerging as a novel problem for the design of a security-guaranteed optical network. This article addresses the resource allocation problem in optical networks secured by QKD. We first discuss a possible architecture for a QKD-enabled optical network, where an SDN controller is in charge of allocating the three types of channels (TDCh, QSCh, and PICh) over different wavelengths exploiting WDM. To save wavelength resources, we propose to adopt OTDM to allocate multiple QSChs and PIChs over the same wavelength. An RWTA algorithm is designed to allocate wavelength and time slot resources for the three types of channels. Different security levels are included in the RWTA algorithm by considering different key updating periods (i.e., the period after which the secure key between two endpoints has to be updated). Illustrative simulation results show the effects of different security-level configuration schemes on resource allocation.
Quantum key distribution (QKD) is considered a secure solution for key distribution and applied in optical networks to overcome security issues by providing key services in different lightpaths. In optical networks, lightpaths in fibers can be used for the delivery of QKD due to their good transmission performance. Accordingly, optical networks secured by QKD have been regarded as an important paradigm, and survivability in this paradigm is an issue worthy of study. In this paper, we focus on the protection schemes for key services in optical networks secured by QKD. Specifically, in consistency with two characteristics of key services (i.e., the key-updating process and key-volume adaptive routing), two key-volume adaptive protection schemes (i.e., dedicated protection and shared protection) are proposed for the networks against link failures. In such scenarios, the designed key-protection threshold can alleviate the tight network resources caused by the key-updating process. Simulation work has been conducted to evaluate the performance of the proposed schemes in terms of blocking probability, resource utilization, and proportion of secret-key consumption with different key-protection thresholds and update periods. Numerical results show that the two proposed schemes are effective in providing protection. Furthermore, evaluating the impact of protection on network security verifies a trade-off that exists between how much protection can be provided for key services versus the overall security of the network, given a certain resource budget.
Quantum key distribution (QKD)-based optical networks utilize quantum mechanics to secure communications by establishing secure, albeit expensive, quantum channels. A critical criterion for these QKD networks is to ensure network availability, which requires each service to adhere to a minimum unavailability constraint to maintain maximum network availability. This paper tackles the challenge of providing dedicated path protection for a select set of key services within QKD optical networks, adhering to specific unavailability constraints to ensure the gap between working and protection paths' unavailability remains within the allowable limit for each services. Considering the constraints of the limited timeslot resources and unavailability for the dedicated-path protection, we develop integer linear programming (ILP) models, to minimize the overall timeslot consumption in QKD optical networks. Additionally, we propose two novel algorithms for timeslot and availability management as minimum timeslot consumption (MTC) algorithm, and maximum availability (MA) algorithm to reduce the timeslot consumption. Simulations indicate that the ILP model based solution achieves the lowest timeslot consumption, however, it requires considerably more processing time compared to the proposed MTC and MA algorithms. Moreover, the MTC and MA algorithms outperform conventional dedicated-path protection (CDP) and fixed routing (FR) algorithms in reducing total timeslot consumption and improving average unavailability.
Quantum key distribution (QKD)-enabled optical networks utilize quantum mechanics to secure communications by establishing secure quantum channels. A critical criterion for QKD-enabled optical networks is ensuring network availability, which requires each quantum key service to adhere to a maximum unavailability constraint to maintain the network availability. This paper addresses the challenge of offering dedicated path protection for quantum key services in QKD-enabled optical networks. It ensures that the unavailability gap between the working and protection paths remains within the allowable limit for each quantum key service, adhering to specific unavailability constraints. Considering the constraints of the limited timeslot resources and network availability, we proposed quantum key service approach named a maximum availability (MA) algorithm. Simulation results indicate that the MA algorithm surpasses both the traditional dedicated-path protection (TDP) and fixed dedicated-path routing (FDR) algorithms in reducing total timeslot consumption and enhancing average availability.
In quantum key distribution (QKD)-secured optical networks, blocking increases with the number of QKD lightpath requests as well as with the number of times modification required to improve the security level of QKD lightpath requests. The blocking is severe problem in such networks because of the limited number of resources (wavelengths and time-slots) in each fiber link. In this paper, we propose a priority order-based routing wavelength and time-slot allocation (POB-RWTA) scheme to reduce the blocking of QKD lightpath requests. In the proposed POB-RWTA scheme, the QKD lightpath requests are served according to their priority order. The priority order of each QKD lightpath request is based on the security level. The blocking of high priority lightpath requests (HPLRs) and total incoming QKD lightpath requests due to limited resources can be reduced using the above criterion of priority order. The performance analysis of the proposed POB-RWTA scheme is made in terms of the success probability of QKD lightpath requests considering different wavelengths for QSCh and the probability of secret key update failure. We compared the proposed POB-RWTA scheme with a non-priority order-based routing wavelength and time-slot allocation (NPOB-RWTA) scheme. Simulations performed on NSFNET topology show that by using the POB-RWTA scheme, the success probability of HPLRs and total incoming QKD lightpath requests are significantly improved as compared to NPOB-RWTA.