Index-hiding for topology-hiding QKD path validation

Achieve index-hiding in a topology-hiding, policy-compliant path-validation protocol for quantum key distribution networks by constructing a variant in which each intermediate repeater node does not learn its own position (index) on the audited path while preserving the protocol’s security guarantees, including path-hiding and verifiable policy compliance.

Background

The paper introduces a topology-hiding path validation protocol for QKD networks that enables receivers to verify policy compliance (e.g., certified devices, node-disjointness) without revealing sensitive topology information. In its current form, the protocol reveals a node’s position on the path to that node, while concealing the overall path length from all but the last node.

The authors identify further privacy strengthening—specifically, preventing nodes from learning their own position (index) along the path—as an open direction. Achieving this index-hiding property would enhance operator confidentiality while maintaining auditability for receivers.