Why Bitcoin Will Fail to Scale?

【Author】 Malik, Nikhil; Aseri, Manmohan; Singh, Param Vir; Srinivasan, Kannan

【Source】MANAGEMENT SCIENCE

【Abstract】Bitcoin falls dramatically short of the scale provided by banks for payments. Currently, its ledger grows by the addition of blocks of similar to 2,000 transactions every 10 minutes. Intuitively, one would expect that increasing the block capacity would solve this scaling problem. However, we show that increasing the block capacity would be futile. We analyze strategic interactions of miners, who are heterogeneous in their power over block addition, and users, who are heterogeneous in the value of their transactions, using a game-theoretic model. We show that a capacity increase can facilitate large miners to tacitly collude-artificially reversing back the capacity via strategically adding partially filled blocks in order to extract economic rents. This strategic partial filling crowds out low-value payments. Collusion is sustained if the smallest colluding miner has a share of block addition power above a lower bound. We provide empirical evidence of such strategic partial filling of blocks by large miners of Bitcoin. We show that a protocol design intervention can breach the lower bound and eliminate collusion. However, this also makes the system less secure. On the one hand, collusion crowds out low-value payments; on the other hand, if collusion is suppressed, security threatens high-value payments. As a result, it is untenable to include a range of payments with vastly different outside options, willingness to bear security risk, and delay onto a single chain. Thus, we show economic limits to the scalability of Bitcoin. Under these economic limits, collusive rent extraction acts as as an effective mechanism to invest in platform security and build responsiveness to demand shocks. These traits are otherwise hard to attain in a disintermediated setting owing to the high cost of consensus.

【Keywords】Bitcoin; blockchain; miners; collusion; micropayments; scalability; security

【标题】为什么比特币无法扩展？

【摘要】比特币的规模远远比不上银行提供的支付服务。目前，它的账本以每10分钟增加2000笔交易区块的速度增长。直观地说，人们会期望增加块容量可以解决这个扩展问题。然而，我们证明增加区块容量是徒劳的。我们使用博弈论模型分析了矿工和用户之间的战略交互，这些矿工对区块添加的权力是异构的，而用户的交易价值是异构的。我们表明，产能增加可以促进大型矿工暗中串通——通过战略性地增加部分填充的区块来人为地逆转产能，以获取经济租金。这种战略性的部分填充方式挤出了低价值的支付。如果最小的勾结矿工拥有高于下限的区块添加权份额，则勾结就会持续。我们提供了大型比特币矿工这种战略性部分填充区块的经验证据。我们表明，协议设计干预可以突破下限并消除串通勾结。但是，这也使系统的安全性降低。一方面，串通勾结排挤了低价值支付；另一方面，如果勾结被压制，安全就会威胁到大额支付。因此，将一系列具有截然不同的外部选择、承担安全风险的意愿和延迟到单个链上的支付包括在内是站不住脚的。因此，我们展示了比特币可扩展性的经济限制。在这些经济限制下，串通取租作为投资平台安全和建立响应需求冲击的有效机制。由于达成共识的高昂成本，这些特征在非中介环境中很难获得。

【关键词】比特币；区块链；矿工；共谋串通；小额支付；可扩展性；安全

【收录时间】2022-09-06

【文献类型】Article; Early Access

【论文大主题】FT50 / UTD24

【论文小主题】挖矿

【影响因子】6.172

【翻译者】王佳鑫