Dynamic key management strategy based on Lagrangian relaxation multi-constraint optimization

With the rapid development of quantum communication technology, quantum key distribution (QKD) provides unconditional secure communication based on the principles of quantum mechanics. In the scenario of multi-service concurrency, it faces the challenges of dynamic resource allocation and complex network scheduling. The traditional key pool management mechanism has problems such as low key resource utilization and difficulty in coordinating multi-dimensional constraints in path optimization, which cannot meet the dynamically changing service quality requirements. This study proposes a quantum key pool architecture with dynamic resource management capabilities. The architecture adopts hierarchical key pool management and adds key recovery mechanism and key dynamic transfer function. For the path optimization problem under multiple constraints, the Lagrangian dual decomposition method is used to establish a mathematical model. The model considers multiple key factors such as bandwidth and delay, and designs an efficient heuristic algorithm to solve the optimal routing strategy. The simulation results show that the proposed algorithm has good performance in terms of service request success rate, key resource utilization, key remaining rate, etc. This study provides a new idea for key distribution and resource allocation in quantum networks, which will help promote the further development of quantum communication technology.