# Anonymity Preserving Byzantine Vector Consensus

## TL;DR

This paper introduces AVCP, an efficient, resilient distributed protocol for anonymous vector consensus that preserves voter anonymity, tolerates Byzantine faults, and is practical for geo-distributed deployment.

## Contribution

It presents AVCP, a novel protocol combining traceable ring signatures and vector consensus reduction, achieving optimal Byzantine fault tolerance with practical efficiency.

## Key findings

- Achieves anonymous consensus with up to one-third Byzantine faults.
- Operates with linear communication and constant message overhead.
- Successfully deployed on 100 geo-distributed machines, reaching decisions within 10 seconds.

## Abstract

Collecting anonymous opinions finds various applications ranging from simple whistleblowing, releasing secretive information, to complex forms of voting, where participants rank candidates by order of preferences. Unfortunately, as far as we know there is no efficient distributed solution to this problem. Previously, participants had to trust third parties, run expensive cryptographic protocols or sacrifice anonymity. In this paper, we propose a resilient-optimal solution to this problem called AVCP, which tolerates up to a third of Byzantine participants. AVCP combines traceable ring signatures to detect double votes with a reduction from vector consensus to binary consensus to ensure all valid votes are taken into account. We prove our algorithm correct and show that it preserves anonymity with at most a linear communication overhead and constant message overhead when compared to a recent consensus baseline. Finally, we demonstrate empirically that the protocol is practical by deploying it on 100 machines geo-distributed in 3 continents: America, Asia and Europe. Anonymous decisions are reached within 10 seconds with a conservative choice of traceable ring signatures.