It Does Not Follow. Response to "Yes They Can! ..."

TL;DR

This paper refutes claims against a quantum communication protocol, confirming the original conclusions and identifying a different protocol that offers security features under quantum-man-in-the-middle attacks.

Contribution

It defends the security claims of a quantum protocol and introduces an alternative protocol with proven security features against QMM attacks.

Findings

Original protocol's security claims are valid.

Two considered protocols lack critical disturbance and valid privacy amplification.

An alternative protocol with security features is identified.

Abstract

This a response to "Yes They Can! ..." (a comment on [5]) by J.S. Shaari et al. [9]. We show that the claims in the comment do not hold up and that all the conclusions obtained in [5] are correct. In particular, the two considered kinds of two-way communication protocols (ping-pong and LM05) under a quantum-man-in-the-middle (QMM) attack have neither a critical disturbance (D), nor a valid privacy amplification (PA) procedure, nor an unconditional security proof. However, we point out that there is another two-way protocol which does have a critical D and a valid PA and which is resistant to a QMM attack.