Zero knowledge proof protects quantum network routes without revealing paths
Certifying Hidden Paths: Scalable Topology Assurance for QKD Networks
Cryptography and Security
Summary
Quantum networks use special keys for secure communication, but the paths these keys travel must be trusted. The authors show a way for network providers to prove that safe paths exist without revealing the paths themselves. They do this by certifying parts of the network separately and proving this information using cryptography, so the network’s layout stays private. Their approach works efficiently even on larger networks and hides details like the route length.
What this means in practice
- •For quantum network operators: Prove existence of secure communication routes without disclosing network structure to partners or customers.
- •For cryptographic service providers: Implement privacy-respecting route verification in quantum-safe communication products that require trust but conceal internal topology.$Commercial implications: Enables building commercial quantum key distribution services that assure route security without exposing sensitive network layout.
Authors
Alessandro Colombo, Margherita Cozzolino, Stephan Krenn, Thomas Lorünser
Abstract
Large-scale Quantum Key Distribution (QKD) networks rely on trusted repeaters, making the security properties of the selected communication path an essential part of end-to-end assurance. At the same time, network operators may be unwilling to disclose their internal topology. We present a topology-certification mechanism that lets a provider prove in zero knowledge that policy-compliant routes between two endpoints exist, without disclosing the routes in an individual presentation. Our main idea is to certify nodes and edges independently using multi-message signatures, rather than signing the complete graph as one object. For a route chosen in advance, proof size and cryptographic proving and verification work depend on its positions and attributes, independently of the overall network size, whereas route discovery and certification have separate graph-dependent costs. The construction hides the actual route length up to a public bound and sketches extensions to node-disjoint routes and monotonic additions within a graph epoch. We give a formal security model and conditional proofs of unforgeability and graph hiding for a generic construction. For a BBS-based construction, presentation-size estimates remain below $300$\,KiB at $\ell=m=n=50$, and measured generation and verification times remain below $400$\,ms at $\ell=64$ and $m=n=8$.