Quantum resistance is vital for emerging cryptographic systems as quantum technologies continue to advance towards large-scale, fault-tolerant quantum computers. Resistance may be offered by quantum key distribution (QKD), which provides information-theoretic security using quantum states of photons, but may be limited by transmission loss at long distances. An alternative approach uses classical means and is conjectured to be resistant to quantum attacks, so-called post-quantum cryptography (PQC), but it is yet to be rigorously proven, and its current implementations are computationally expensive. To overcome the security and performance challenges present in each, here we develop hybrid protocols by which QKD and PQC inter-operate within a joint quantum-classical network. In particular, we consider different hybrid designs that may offer enhanced speed and/or security over the individual performance of either approach. Furthermore, we present a method for analyzing the security of hybrid protocols in key distribution networks. Our hybrid approach paves the way for joint quantum-classical communication networks, which leverage the advantages of both QKD and PQC and can be tailored to the requirements of various practical networks.

翻译：随着量子技术持续向大规模容错量子计算机迈进，抗量子性对于新兴密码系统至关重要。量子密钥分发（QKD）利用光子的量子态提供信息论安全性，可提供抗量子能力，但在长距离传输中可能受限于传输损耗。另一种方法使用经典手段，并被认为能抵抗量子攻击，即所谓的后量子密码学（PQC），但其抗量子性尚未得到严格证明，且当前实现方案计算成本高昂。为克服二者各自存在的安全与性能挑战，本文开发了混合协议，使QKD与PQC在联合量子-经典网络中协同运作。我们特别探讨了多种混合设计方案，这些方案相较于单一方法可能提供更快的速度和/或更高的安全性。此外，我们提出了一种分析密钥分发网络中混合协议安全性的方法。我们的混合方案为构建联合量子-经典通信网络开辟了道路，此类网络能同时利用QKD与PQC的优势，并可根据不同实际网络的需求进行定制。