HotPoW: Finality from Proof-of-Work Quorums
This work addresses a fundamental problem in blockchain consensus for decentralized systems, offering a novel solution that is not incremental but introduces a new theoretical framework.
The paper tackles the conflict between inclusiveness and security in proof-of-work systems by developing a theory of proof-of-work quorums, bridging Byzantine and Nakamoto consensus, and presents HotPoW, a scalable protocol that achieves finality with small storage overhead and less complexity than sidechain-based methods.
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.