Continuous-variable quantum authentication of physical unclonable keys: Security against an emulation attack

TL;DR

This paper analyzes the security of a quantum authentication protocol using physical unclonable keys, demonstrating it is secure against emulation attacks within realistic technological parameters.

Contribution

It provides a sufficient security condition against emulation attacks for a quantum authentication protocol using continuous-variable light.

Findings

Protocol is secure against emulation attack under certain physical parameters.

Security analysis uses Holevo's bound and Fano's inequality.

Security conditions are achievable with current technology.

Abstract

We consider a recently proposed entity authentication protocol, in which a physical unclonable key is interrogated by random coherent states of light, and the quadratures of the scattered light are analysed by means of a coarse-grained homodyne detection. We derive a sufficient condition for the protocol to be secure against an emulation attack, in which an adversary knows the challenge-response properties of the key, and moreover he can access the challenges during the verification. The security analysis relies on Holevo's bound and Fano's inequality, and suggests that the protocol is secure against the emulation attack for a broad range of physical parameters that are within reach of today's technology.