Security-aware multi-path routing with XOR-based key fusion for quantum key distribution network

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.