Comment on "Complete insecurity of quantum protocols for classical two-party computation"

TL;DR

This paper critiques a recent claim about the insecurity of quantum protocols for classical two-party computation, arguing that the proof's security assumptions are not sufficiently general or necessary.

Contribution

It challenges the previous proof by showing that the security definition used is only sufficient, not necessary, thus leaving open the possibility of secure quantum protocols.

Findings

The previous proof's security assumption is not necessary for security.

The security definition used is only a sufficient condition.

Quantum protocols may still be secure despite the critique.

Abstract

In a recent paper (Phys. Rev. Lett. 109, 160501 (2012). arXiv:1201.0849), it is claimed that any quantum protocol for classical two-sided computation between Alice and Bob can be proven completely insecure for Alice if it is secure against Bob. Here we show that the proof is not sufficiently general, because the security definition it based on is only a sufficient condition but not a necessary condition.