Reply to Structural Vulnerability in Y00 Protocols

TL;DR

This paper refutes a claimed structural vulnerability in the Y00 quantum encryption protocol, clarifies the misinterpretation behind it, and demonstrates that the simplified model is actually more vulnerable than the original protocol.

Contribution

It provides a rebuttal to a previous vulnerability claim, clarifies the misunderstanding, and compares the security of a simplified model to the original Y00 protocol.

Findings

The alleged vulnerability was due to a misinterpretation.

The simplified model is more vulnerable than the original Y00.

The original Y00 protocol remains secure against the claimed attack.

Abstract

The paper arXiv:2412.07300v1 [quant-ph] 10 Dec 2024, entitled "Structural Vulnerability in Y00 Protocols", by Kentaro Imafuku analyzes "Secure Communication Using Mesoscopic Coherent States", Phys. Rev. Lett., 90:227901, Jun 2003, by Geraldo A. Barbosa, Eric Corndorf, Prem Kumar, and Horace P. Yuen. Imafuku states that in his analyzes a structural vulnerability was revealed that enables the leakage of secret information from the measurement results in the Y00 protocol. Furthermore, it is also stated that an even simpler model, but based on the same original principles, can be more efficient than the original Y00 protocol. This reply shows that: 1) the alleged vulnerability is due to a misinterpretation of one result by Imafuku and 2) that the simple model proposed by him is more vulnerable than the original Y00.