Protection schemes for key service in optical networks secured by quantum key distribution (QKD)

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.