On the security of two-way quantum key distribution

TL;DR

This paper defends the security of two-way quantum key distribution against recent critiques, clarifying misconceptions about the protocol's workings and attack strategies.

Contribution

It clarifies misunderstandings about two-way quantum key distribution security and counters recent flawed attack-based criticisms.

Findings

Two-way QKD protocols are secure against certain attack strategies.

Misunderstandings about protocol operations lead to incorrect security conclusions.

The critique in question is based on flawed assumptions about the protocol.

Abstract

An author (arXiv:1709.09262 [quant-ph] (2017), Nanoscale Research Letters (2017) 12:552) has recently questioned the security of two-way quantum key distribution schemes by referring to attack strategies which leave no errors in the (raw) key shared by the legitimate parties. We argue that the article is based on a flawed understanding of the actual workings of a two-way protocol, thus the erroneous conclusions drawn thereof.