Incorporating device characterization into security proofs

TL;DR

This paper develops a rigorous framework for incorporating device characterization into security proofs for quantum key distribution, ensuring practical deployment with certified device parameters.

Contribution

It introduces a formal approach to integrate device certification procedures into QKD security proofs, clarifying valid conclusions and addressing misconceptions.

Findings

Framework for analyzing device characterization procedures

Requirements for security proofs and certification methods

Discussion on connections to composable security

Abstract

Typical security proofs for quantum key distribution (QKD) rely on having some model for the devices, with the security guarantees implicitly relying on the values of various parameters of the model, such as dark count rates or detector efficiencies. Hence to deploy QKD in practice, we must establish how to certify or characterize the model parameters of a manufacturer's QKD devices. We present a rigorous framework for analyzing such procedures, laying out concrete requirements for both the security proofs and the certification or characterization procedures. In doing so, we describe various forms of conclusions that can and cannot be validly drawn from such procedures, addressing some potential misconceptions. We also discuss connections to composable security frameworks and some technical aspects that remain to be resolved in that direction.