Hao Qin

We present the strategic framework and technical foundations behind the development of the National Quantum-Safe Network (NQSN) in Singapore—a resilient, fully interoperable quantum-safe network. The testbed features a star-topology architecture built on production-grade fiber infrastructure, supporting multi-protocol quantum key distribution (QKD) and diverse applications from multiple vendors. A centralised key and network management system underpins its interoperability, enabling seamless integration across technologies. We further explore a range of quantum-secured use cases, including data center connectivity, edge computing, hybrid QKD–post-quantum cryptography (PQC) encryption, and multi-layer integration within the OSI stack. These technical insights demonstrate the feasibility and flexibility of deploying quantum-safe capabilities in a multi-input, multi-output network environment.

We have shown how to conduct QKD vulnerability assessment in practice, based on a sound methodology inherited from Common Criteria. Taking a running CV-QKD system as a reference platform, we have experimentally tested and rated two different attack paths exploiting a common threat: detector saturation. Our results illustrate the importance of rating attacks in order to prioritize the implementation of countermeasures and to steer the design and engineering of practical QKD systems towards the highest possible security standards, paving the way to their security certification.

The National Quantum-Safe Network (NQSN) in Singapore is a nationwide collaborative platform and a field-deployed test-bed aimed at demonstrating quantum-safe cryptography solutions. NQSN links up academic, public and private members, targets trials for quantum key distribution (QKD) network with different QKD protocols, post-quantum cryptography (PQC) and classical symmetric key technologies.