Quantum key distribution (QKD) networks provide information-theoretically secure keys for distant parties, emerging as a vital alternative to classical cryptography infrastructures threatened by quantum computing. In QKD networks, the immediacy of key supply service is crucial to the security and performance of applications, as their data must be encrypted before transmission. While key buffering can enable instant key supply services, existing schemes rely on heuristic solutions that incur prohibitive key resource consumption, thus significantly hindering practical deployment. To address this issue, we propose QuIKS, an instant key supply scheme based on adaptive buffering, offering the dominant advantage of near-zero key supply latency while consuming ultra-low key resources (i.e., ultra-low buffer size). Specifically, it is built upon a novel analytical model that determines the minimum buffer size required to guarantee near-zero-latency key supply performance. Guided by this model, QuIKS introduces a lightweight two-phase control algorithm that dynamically determines key relaying requests and adjusts the buffer size by probing real-time application patterns and network conditions. Experiments on a real QKD network testbed demonstrate that QuIKS achieves near-zero key supply latency while providing a more than 10-fold reduction in key buffer size compared to state-of-the-art schemes.

翻译：量子密钥分发（QKD）网络能够为相距遥远的各方提供具备信息论安全性的密钥，正成为受量子计算威胁的经典密码基础设施的重要替代方案。在QKD网络中，密钥供给服务的即时性对应用的安全性和性能至关重要，因为这些应用的数据必须在传输前进行加密。虽然密钥缓冲能够实现即时密钥供给服务，但现有方案依赖启发式方法，导致密钥资源消耗过高，严重阻碍了实际部署。为解决此问题，我们提出QuIKS，一种基于自适应缓冲的即时密钥供给方案，其核心优势在于实现近零密钥供给延迟的同时消耗超低密钥资源（即超低缓冲区大小）。具体而言，该方案建立于一种新型分析模型之上，该模型能够确定保证近零延迟密钥供给性能所需的最小缓冲区大小。在此模型指导下，QuIKS引入了一种轻量级两阶段控制算法，通过探测实时应用模式与网络状况，动态确定密钥中继请求并调整缓冲区大小。在真实QKD网络测试平台上的实验表明，与现有最优方案相比，QuIKS在实现近零密钥供给延迟的同时，将密钥缓冲区大小降低了超过10倍。