Security limitation on a class of device-independent quantum key distribution

TL;DR

This paper reveals a security vulnerability in certain device-independent quantum key distribution protocols, showing that an eavesdropper can exploit statistical fluctuations to compromise the secret key, unlike in device-dependent protocols.

Contribution

It demonstrates a specific security limitation in DI quantum key distribution protocols caused by statistical fluctuations, highlighting a fundamental difference from DD protocols.

Findings

Eavesdropper can exploit statistical fluctuations to gain secret key information.

Cheating strategy effective in DI protocols but not in DD protocols.

DI protocols are less secure than DD protocols under certain conditions.

Abstract

Recently there were many proposals on device-independent (DI) quantum key distribution protocol whose security is based on the violation of the Clauser-Horne-Shimony-Holt inequality. However, as a statistical law, a certain extent of fluctuation has to be allowed. We show that the eavesdropper can make use of this property to obtain a remarkable part of the secret key by replacing some of the DI nonlocal boxes with local ones. On the contrary, the same cheating strategy does not apply to the device-dependent (DD) version of the protocol. Thus such kind of DI protocol is less secure than its DD counterpart.