Eavesdropping of two-way coherent-state quantum cryptography via Gaussian quantum cloning machines

TL;DR

This paper analyzes the security of a two-way coherent-state quantum cryptography protocol against attacks using Gaussian quantum cloning machines, revealing potential vulnerabilities in quantum key distribution.

Contribution

It introduces a detailed security analysis of a recent two-way quantum cryptography protocol against Gaussian cloning-based attacks.

Findings

Identifies potential security weaknesses in the protocol.

Demonstrates how Gaussian cloning machines can compromise key security.

Provides insights into the robustness of two-way quantum cryptography.

Abstract

We consider one of the quantum key distribution protocols recently introduced in Ref. [Pirandola et al., Nature Physics 4, 726 (2008)]. This protocol consists in a two-way quantum communication between Alice and Bob, where Alice encodes secret information via a random phase-space displacement of a coherent state. In particular, we study its security against a specific class of individual attacks which are based on combinations of Gaussian quantum cloning machines.