A Study on Nine Years of Bitcoin Transactions: Understanding Real-world Behaviors of Bitcoin Miners and Users

Bitcoin is the world's first blockchain-based, peer-to-peer cryptocurrency system. Being tremendously successful, the Bitcoin system is designed to support reliable, secure, and trusted transactions between untrusted peers. Since its release in 2009, the Bitcoin system has rapidly grown to an unprecedentedly large scale. However, the real-world behaviors of miners and users in the system and the efficacy of the original Bitcoin system design in the field deployment still remain unclear, hindering us from understanding its internals and developing the next-generation cryptocurrency system. In this paper, we study the behaviors of Bitcoin miners and users and their interactions based on quantitative analysis of more than nine years of Bitcoin transaction history, from its first release on January 3rd, 2009 to April 30th, 2018. We have analyzed over 300 million transaction records to study the transactions' processing, confirmation, and implementation. We have obtained several critical findings regarding how the miners and users exploit the high degree of freedom provided by the Bitcoin system to achieve their own interests. For example, we find that miners often attempt to maximize their profits even by sacrificing system performance; users could try to speed up the transaction processing by mistakenly trading off security for reduced latency. Such unexpected behaviors, to some degree, deviate from the original design purposes of the Bitcoin system and could bring undesirable consequences. Besides revealing several unexpected behaviors of the Bitcoin miners and users in the real world, we have also discussed the associated system implications as well as optimization opportunities in the future.