[论文解读] Blockchain Consensuses Algorithms: A Survey.

Md Sadek Ferdous, Mohammad Jabed Morshed Chowdhury+2 more|arXiv (Cornell University)|Jan 20, 2020

Blockchain Technology Applications and Security被引用 10

一句话总结

本文对区块链共识算法进行了全面综述，提出了其特性的统一分类体系，并分析了超过100种加密货币，以识别趋势与局限性。该研究提出了一种决策树，以根据系统需求指导算法选择，提供了一个系统化的框架，用于评估不同区块链设计在性能、安全性和可扩展性方面的表现。

ABSTRACT

In recent years, blockchain technology has received unparalleled attention from academia, industry, and governments all around the world. It is considered a technological breakthrough anticipated to disrupt several application domains. This has resulted in a plethora of blockchain systems for various purposes. However, many of these blockchain systems suffer from serious shortcomings related to their performance and security, which need to be addressed before any wide-scale adoption can be achieved. A crucial component of any blockchain system is its underlying consensus algorithm, which in many ways, determines its performance and security. Therefore, to address the limitations of different blockchain systems, several existing as well novel consensus algorithms have been introduced. A systematic analysis of these algorithms will help to understand how and why any particular blockchain performs the way it functions. However, the existing studies of consensus algorithms are not comprehensive. Those studies have incomplete discussions on the properties of the algorithms and fail to analyse several major blockchain consensus algorithms in terms of their scopes. This article fills this gap by analysing a wide range of consensus algorithms using a comprehensive taxonomy of properties and by examining the implications of different issues still prevalent in consensus algorithms in detail. The result of the analysis is presented in tabular formats, which provides a visual illustration of these algorithms in a meaningful way. We have also analysed more than hundred top crypto-currencies belonging to different categories of consensus algorithms to understand their properties and to implicate different trends in these crypto-currencies. Finally, we have presented a decision tree of algorithms to be used as a tool to test the suitability of consensus algorithms under different criteria.

研究动机与目标

• 为解决现有研究中对区块链共识算法缺乏全面分析的问题。
• 建立共识算法特性的统一分类体系，以实现系统化比较。
• 分析主要共识算法在现实世界加密货币中的性能与安全影响。
• 识别顶级加密货币中共识机制采用的趋势。
• 提供一种决策树工具，根据特定应用场景的需求选择合适的共识算法。

提出的方法

• 设计涵盖安全性、可扩展性和最终性等特性的共识算法属性综合分类体系。
• 系统性地分析按共识机制分类的100多种顶级加密货币。
• 从容错性、延迟、吞吐量和能效等方面评估每种算法的行为表现。
• 映射共识设计选择与其在现实世界中的性能结果之间的关系。
• 基于去中心化、最终性、吞吐量等关键系统需求构建决策树。
• 使用表格形式对共识算法在多个维度上的表现进行可视化对比。

实验结果

研究问题

• RQ1 不同共识算法在安全性、可扩展性和最终性方面有何差异？
• RQ2 在顶级加密货币中，共识机制的采用趋势如何？
• RQ3 现有共识算法在性能与安全性之间存在哪些关键权衡？
• RQ4 哪些共识算法最适合特定的区块链用例？
• RQ5 共识算法的设计选择如何影响现实世界区块链系统的性能？

主要发现

• 综述发现先前研究存在显著空白，特别是在属性分析的完整性以及对主要共识算法的覆盖方面。
• 在顶级加密货币中观察到广泛的共识机制多样性，其中工作量证明（Proof of Stake）及其变体在近期部署中占据主导地位。
• 吞吐量和最终性时间等性能指标差异显著，部分新型算法已实现亚秒级最终性与高吞吐量。
• 对抵抗Sybil攻击和eclipse攻击等安全属性的文档记录在现有算法中存在不一致。
• 决策树为将应用需求映射到合适的共识算法提供了实用工具，提升了选择过程的透明度。
• 表格对比显示，没有一种共识算法在所有维度上均表现卓越，进一步强调了需根据具体场景进行设计选择。