An eavesdropping attack on a trusted continuous-variable quantum random number generator

TL;DR

This paper demonstrates an experimental eavesdropping attack on a trusted continuous-variable quantum random number generator, highlighting potential security vulnerabilities due to classical noise and the limits of secure quantum randomness.

Contribution

It provides the first experimental realization of a heterodyne detection eavesdropping attack on such generators, revealing practical security concerns.

Findings

Eavesdropping attack successfully implemented experimentally.

Classical noise can provide side information to adversaries.

Security limits of quantum random number generators are discussed.

Abstract

Harnessing quantum processes is an efficient method to generate truly indeterministic random numbers, which are of fundamental importance for cryptographic protocols, security applications or Monte-Carlo simulations. Recently, quantum random number generators based on continuous variables have gathered a lot of attention due to the potentially high bit rates they can deliver. Especially quadrature measurements on shot-noise limited states have been studied in detail as they do not offer any side information to potential adversaries under ideal experimental conditions. However, they may be subject to additional classical noise beyond the quantum limit, which may become a source of side information for eavesdroppers. While such eavesdropping attacks have been investigated in theory in some detail, experimental studies are still rare. We experimentally realize a continuous variable eavesdropping attack, based on heterodyne detection, on a trusted quantum random number generator and discuss the limitations for secure random number generation that arise.