Secure Multi-Party Computation with a Dishonest Majority via Quantum Means

TL;DR

This paper proposes a quantum-based scheme for secure multi-party computation that achieves higher security thresholds than classical methods by leveraging entangled quantum states, enabling secure computation even with a dishonest majority.

Contribution

It introduces a novel quantum protocol for multi-party computation with improved security thresholds, including a two-party scheme and a generalization to n-party polynomial computations.

Findings

Quantum correlations enable near-private two-party computation.

Passive security with threshold t=2 is achievable.

Higher security thresholds than classical bounds are demonstrated.

Abstract

We introduce a scheme for secure multi-party computation utilising the quantum correlations of entangled states. First we present a scheme for two-party computation, exploiting the correlations of a Greenberger-Horne-Zeilinger state to provide, with the help of a third party, a near-private computation scheme. We then present a variation of this scheme which is passively secure with threshold t=2, in other words, remaining secure when pairs of players conspire together provided they faithfully follow the protocol. We show that this can be generalised to computations of n-party polynomials of degree 2 with a threshold of n-1. The threshold achieved is significantly higher than the best known classical threshold, which satisfies the bound t<n/2.