A Quantum Key Distribution Network: Integrated Design and Prototypical Implementation

Quantum key distribution (QKD) is a cryptographic primitive, which offers an extremely high security standard known as unconditional or information-theoretic security, relying on intrinsically quantum properties of communication (light) signals. A general trusted relay technique was adopted and developed by the Integrated EU-project SECOQC. What makes the SECOQC approach unique is on the one hand the introduction of an integrated network design, specifically tailored for the distribution of secrets, which is logically completely independent from the communication network employed by the corresponding security application layer. On the other hand, from a structural design point of view, there is a clear system separation into two basic components: a quantum key generation one, realized by a QKD link, i.e. a pair of QKD devices connected by quantum channel, and a classical secret maintenance and distribution one, realized by a dedicated "node device" with a universal interface between these two components. The main deliverable of SECOQC is the implementation and operation of a test network in Vienna and lower Austria. The paper focuses on the design approach developed in SECOQC and the implementation status of the prototype.