Blockchain plays an important role in cryptocurrency markets and technology services. However, limitations on high latency and low scalability retard their adoptions and applications in classic designs. Reconstructed blockchain systems have been proposed to avoid the consumption of competitive transactions caused by linear sequenced blocks. These systems, instead, structure transactions/blocks in the form of Directed Acyclic Graph (DAG) and consequently re-build upper layer components including consensus, incentives, \textit{etc.} The promise of DAG-based blockchain systems is to enable fast confirmation (complete transactions within million seconds) and high scalability (attach transactions in parallel) without significantly compromising security. However, this field still lacks systematic work that summarises the DAG technique. To bridge the gap, this Systematization of Knowledge (SoK) provides a comprehensive analysis of DAG-based blockchain systems. Through deconstructing open-sourced systems and reviewing academic researches, we conclude the main components and featured properties of systems, and provide the approach to establish a DAG. With this in hand, we analyze the security and performance of several leading systems, followed by discussions and comparisons with concurrent (scaling blockchain) techniques. We further identify open challenges to highlight the potentiality of DAG-based solutions and indicate their promising directions for future research.
翻译:然而,对高潜值和低伸缩性的限制妨碍了其采用和在经典设计中的应用。 已经提议了重建的链条系统,以避免因线性序列块造成的竞争性交易消耗。相反,这些系统以直接环形图(DAG)的形式结构交易/封块,从而重建上层部分,包括共识、激励、Textit{etc。 }基于DAG的链条系统的许诺是,能够快速确认(在百万秒内完成交易)和高度可伸缩性(平行进行交易),而不会大大损害安全。然而,这个领域仍然缺乏系统化的工作,无法对DAG技术进行总结。为了缩小差距,这种知识系统化(SOK)对基于DAG的链条系统进行了全面分析。通过对开放源码系统进行拆解和审查学术研究,我们完成了系统的主要构件和特征,提供了建立DAG的方法(平行进行交易),同时,我们用手头分析各种安全性和系统的潜在表现。我们用一系列方法来进一步分析这些方法,通过共同分析各种解决办法。