Delay Impact on Stubborn Mining Attack Severity in Imperfect Bitcoin Network

Abstract

Bitcoin is the largest Proof-of-Work (PoW) public blockchain but is vulnerable to various attacks like stubborn mining attack, which greatly downgrades both system throughput and benefits malicious miners (attackers). The existing works assume miners receive new blocks immediately after block generation, which is away from reality. This article aims to quantify the stubborn mining attack severity in an imperfect Bitcoin network in which there exists block receiving delay. In this article, we first develop an analytic model to capture blockchain dynamics, and then derive formulas of both relative revenue and system throughput, which are applied to study attack severity. Experiment results validate our quantitative analysis method and show that imperfect networks favor attackers. Moreover, the results recommend a blockchain system to be composed of small mining pools to get fair revenue distribution, and minimize its network delay and fork probability to get high TPS.