Trusted relays are the main state-of-the-art way to realize quantum key distribution networks. However, it is hard to require that all nodes in the network are fully trusted. In a multipath key-transmission mechanism, the nodes can be weakly trusted because the secret key can be split into many parts and each part is transmitted to the receiver through a different path. However, if the capacity of a node’s quantum key pool is poorly designed, an attacker, Eve may eavesdrop on the communicating parties’ secret message by initiating a redirection attack. In this paper, we show that Eve can trigger a cascading collapse effect by collapsing one of the edges in the network and forcing the communication parties to transmit the message through the nodes controlled by Eve. The influence of the traffic transfer ratio and the control parameters of the edge load on the breakdown probability of the edge are analyzed using a simulation. In order to effectively defend against the cascading attack, it is important for the designer to handle the relationship between the traffic and the capacity of the quantum key pool of each node in the network.

可信中继是实现量子密钥分发网络的最先进的主要方式。但是，很难要求网络中的所有节点都完全可信。在多路径密钥传输机制中，节点可能是弱信任的，因为密钥可以分成许多部分，每个部分通过不同的路径传输到接收者。但是，如果节点的量子密钥池容量设计不当，攻击者 Eve 可能会通过发起重定向攻击来窃听通信双方的秘密消息。在本文中，我们展示了 Eve 可以通过折叠网络中的一条边并迫使通信方通过 Eve 控制的节点传输消息来触发级联崩溃效应。通过仿真分析了交通转移率和边缘负载控制参数对边缘故障概率的影响。为了有效防御级联攻击，设计者处理好网络中每个节点的流量与量子密钥池容量之间的关系是很重要的。