Defending against the nothing-at-stake problem in multi-threaded blockchains

TL;DR

This paper proposes a novel protection mechanism against the nothing-at-stake problem in multi-threaded blockchains, combining BFT and Nakamoto consensus approaches to enable scalable parallel block production without reconciliation.

Contribution

It introduces a new protection method that leverages both BFT and Nakamoto consensus to address the nothing-at-stake issue in parallel blockchains.

Findings

The proposed method enhances scalability of multi-threaded blockchains.

It effectively mitigates the nothing-at-stake problem in parallel block production.

The approach combines strengths of BFT and Nakamoto consensus for improved security.

Abstract

In blockchain systems, the scarcity of a resource is used as a Sybil protection mechanism. In Proof-of-Work blockchains, that resource is computing power. In the event of a fork, the scarcity of this resource theoretically prevents miners from producing blocks on both branches of a fork. In Proof-of-Stake blockchains, because that resource is token stake, the computational cost of creating a block is negligible. In the event of a fork, and if no specific measures have been taken, rational block producers should extend both branches of the fork. In blockchains with sequential block production, a punishment mechanism known as slashing is often cited as a protection against the nothing-at-stake problem. However, in the context of a blockchain with parallel block production, it seems that slashing is not sufficient against the numerous divergence opportunities. In this paper, we propose a novel protection against the nothing-at-stake problem that takes the most out of BFT and Nakamoto-based consensus. By combining those approaches, we wish to scale up blockchains by allowing parallel block production without reconciliation.