When is Slower Block Propagation More Profitable for Large Miners?

For years, Bitcoin miners put little effort into adopting several widely-acclaimed block acceleration techniques, which, as some argued, would secure their revenues. Their indifference inspires a theory that slower block propagation is beneficial for some miners. In this study, we analyze and confirm this counterintuitive theory. Specifically, by modeling inadvertent slower blocks, we show that a mining coalition that controls more than a third of the total mining power can earn unfair revenue by propagating blocks slower to outsiders. Afterward, we explore the strategies of an attacker that consciously exploits this phenomenon. The results indicate that an attacker with 45% of the total mining power can earn 58% of the total revenue. This attack is alarming as it is equally fundamental but more stealthy than the well-known selfish mining attack. At last, we discuss its detection and defense mechanisms.