An Attack to Quantum Cryptography from Space

TL;DR

This paper highlights a potential security vulnerability in quantum cryptography protocols by neglecting the spatial part of the wave function, proposing an approach to enhance security using Bell's inequality and specific wave function preparation.

Contribution

It reveals a security flaw related to the spatial component of the wave function in quantum key distribution and suggests a method to address this vulnerability.

Findings

Quantum protocols may be insecure in real space despite spin-based security.

Using Bell's inequality can help detect eavesdropping involving spatial wave function components.

Proper preparation of the spatial wave function enhances quantum cryptography security.

Abstract

The promise of secure cryptographic quantum key distribution schemes is based on the use of quantum effects in the spin space. We point out that in fact in many current quantum cryptography protocols the space part of the wave function is neglected. However exactly the space part of the wave function describes the behaviour of particles in ordinary real three-dimensional space. As a result such schemes can be secure against eavesdropping attacks in the abstract spin space but could be insecure in the real three-dimensional space. We discuss an approach to the security of quantum key distribution in space by using Bell's inequality and a special preparation of the space part of the wave function.