Architecture and protocols of the future European quantum key distribution network

A point‐to‐point quantum key distribution (QKD) system takes advantage of the laws of quantum physics to establish secret keys between two communicating parties. Compared to the classical methods, such as public‐key infrastructures, QKD offers unconditional security, which makes it attractive for very high security applications. However, this unprecedent level of security is mitigated by the inherent constraints of quantum communications, such as the limited rates and ranges of an individual point‐to‐point QKD link. A QKD network, which can be built by combining multiple point‐to‐point QKD devices, can alleviate the constraints and enable point‐to‐multi‐point key distribution based on QKD technology. The European project, secure communication based on quantum cryptography (SeCoQC) aims at deploying a prototype QKD network, which will be demonstrated in September 2008, by developing the architecture and the protocols, as well as the specific hardware for long‐range QKD networks. This paper discusses the important aspects of the architecture and the network layer protocols of the SeCoQC QKD network.