HotPoW: Finality from Proof-of-Work Quorums

TL;DR

HotPoW introduces a novel proof-of-work quorum theory that balances inclusiveness and security, enabling scalable, permissionless distributed logs with finality, resilience to attacks, and lower overhead than existing protocols.

Contribution

The paper develops a new theory of proof-of-work quorums and applies it to create HotPoW, a scalable protocol achieving finality with improved security and efficiency over prior methods.

Findings

HotPoW tolerates network latency, churn, and targeted attacks.

The protocol has small storage overhead compared to Nakamoto consensus.

HotPoW demonstrates less complexity than sidechain-based finality protocols.

Abstract

A fundamental conflict of many proof-of-work systems is that they want to achieve inclusiveness and security at the same time. We analyze and resolve this conflict with a theory of proof-of-work quorums, which enables a new bridge between Byzantine and Nakamoto consensus. The theory yields stochastic uniqueness of quorums as a function of a security parameter. We employ the theory in HotPoW, a scalable permissionless distributed log protocol that supports finality based on the pipelined three-phase commit previously presented for HotStuff. We evaluate HotPoW and variants with adversarial modifications by simulation. Results show that the protocol can tolerate network latency, churn, and targeted attacks on consistency and liveness with a small storage overhead compared to plain Nakamoto consensus and less complexity than protocols that rely on sidechains for finality.