The Economics of Bitcoin Mining, or Bitcoin in the Presence of Adversaries

The Bitcoin digital currency depends for its correctness and stability on a combination of cryptography, distributed algorithms, and incentivedriven behavior. We examine Bitcoin as a consensus game and determine that it relies on separate consensus about the rules and about game state. An important aspect of Bitcoin’s design is the mining mechanism, in which participants expend resources on solving computational puzzles in order to collect rewards. This mechanism purportedly protects Bitcoin against certain technical problems such as inconsistencies in the system’s distributed log data structure. We consider the economics of Bitcoin mining, and whether the Bitcoin protocol can survive attacks, assuming that participants behave according to their incentives. We show that there is a Nash equilibrium in which all players behave consistently with Bitcoin’s reference implementation, along with infinitely many equilibria in which they behave otherwise. We also show how a motivated adversary might be able to disrupt the Bitcoin system and “crash” the currency. Finally, we argue that Bitcoin will require the emergence of governance structures, contrary to the commonly held view in the Bitcoin community that the currency is ungovernable.