Bitcoin introduced delegation of control over a monetary system from a select few to all who participate in that system. This delegation is known as the decentralization of controlling power and is a powerful security mechanism for the ecosystem. After the introduction of Bitcoin, the field of cryptocurrency has seen widespread attention from industry and academia, so much so that the original novel contribution of Bitcoin, i.e., decentralization, may be overlooked, due to decentralizations’ assumed fundamental existence for the functioning of such crypto-assets. However, recent studies have observed a trend of increased centralization in cryptocurrencies such as Bitcoin and Ethereum. As this increased centralization has an impact the security of the blockchain, it is crucial that it is measured, towards adequate control. This research derives an initial taxonomy of centralization present in decentralized blockchains through rigorous synthesis using a systematic literature review. This is followed by iterative refinement through expert interviews. We systematically analyzed 89 research papers published between 2009 and 2019. Our study contributes to the existing body of knowledge by highlighting the multiple definitions and measurements of centralization in the literature. We identify different aspects of centralization and propose an encompassing taxonomy of centralization concerns. This taxonomy is based on empirically observable and measurable characteristics. It consists of 13 aspects of centralization, classified over six architectural layers: Governance, Network, Consensus, Incentive, Operational, and Application. We also discuss how the implications of centralization can vary depending on the aspects studied. We believe that this review and taxonomy provides a comprehensive overview of centralization in decentralized blockchains involving various conceptualizations and measures.

比特币引入了对货币系统的控制权，从少数人到参与该系统的所有人。这种授权被称为控制权的下放，是生态系统的强大安全机制。引入比特币之后，加密货币领域受到了业界和学术界的广泛关注，以至于由于去中心化的假定基础存在，使得比特币的原始新贡献（即去中心化）可能被忽略了。加密资产。但是，最近的研究发现，比特币和以太坊等加密货币的集中化趋势有所提高。由于集中度的提高会影响区块链的安全性，因此对其进行衡量以实现充分控制至关重要。这项研究通过使用系统的文献综述，通过严格的综合得出了分散式区块链中存在的集中化的初始分类法。接下来是通过专家访谈进行迭代优化。我们系统地分析了2009年至2019年之间发表的89篇研究论文。我们的研究通过强调文献中集中化的多种定义和度量，为现有知识体系做出了贡献。我们确定了集中化的不同方面，并提出了集中化关注点的涵盖分类法。此分类法基于经验可观察和可测量的特征。它由集中化的13个方面组成，分为六个架构层：治理，网络，共识，激励，运营和应用。我们还将讨论集中化的含义如何根据所研究的方面而变化。我们认为，此审查和分类法提供了涉及各种概念和措施的去中心化区块链集中化的全面概述。