Hybrid Consensus with Quantum Sybil Resistance

TL;DR

This paper introduces a hybrid consensus protocol that leverages quantum position verification as a Sybil resistance mechanism, enhancing security and energy efficiency over traditional proof-of-work and proof-of-stake systems.

Contribution

It presents a novel hybrid consensus protocol combining classical methods with quantum position verification for Sybil resistance, achieving improved security and efficiency.

Findings

Provides a secure consensus protocol using quantum states as a scarce resource.

Achieves faster confirmation times than pure Proof-of-Work protocols.

Offers resilience against wealth concentration issues in Proof-of-Stake systems.

Abstract

Sybil resistance is a key requirement of decentralized consensus protocols. It is achieved by introducing a scarce resource (such as computational power, monetary stake, disk space, etc.), which prevents participants from costlessly creating multiple fake identities and hijacking the protocol. Quantum states are generically uncloneable, which suggests that they may serve naturally as an unconditionally scarce resource. In particular, uncloneability underlies quantum position-based cryptography, which is unachievable classically. We design a consensus protocol that combines classical hybrid consensus protocols with quantum position verification as the Sybil resistance mechanism, providing security in the standard model, and achieving improved energy efficiency compared to hybrid protocols based on Proof-of-Work. Our protocol inherits the benefits of other hybrid protocols, namely the faster confirmation times compared to pure Proof-of-Work protocols, and resilience against the compounding wealth issue that plagues protocols based on Proof-of-Stake Sybil resistance. We additionally propose a spam prevention mechanism for our protocol in the Random Oracle model.