3D-DAG: Scaling Blockchain via DAG

Abstract

Blockchain has been widely recognized as a trusted computing paradigm underpinning Decentralized Applications (DApps). However, low performance and poor scalability of the existing mainstream blockchain designs and implementations render their prospects unattainable, so-called trilemma . Directed Acyclic Graph (DAG) emerged as an alternative blockchain architecture to address the performance and scalability issue. However, the capacity and feasibility of DAG-based blockchain systems still remain of concern, due to a lack of open source implementations and convincing published experimental results. In this article, we propose a DAG-based blockchain, named 3D-DAG , to greatly improve the scalability and performance without compromising security. The system addresses the trilemma of decentralization, scalability, and security. Technically, our 3D-DAG consists of two layers of chains: DAGchain and mainchain . The DAGchain organizes the transactions in DAG topology, without having to solve the forks. They select a small group of validators from a large number of miners to make up the committee for consensus procedures. The design of DAGchain improves scalability by enabling parallel transaction processing. Based on that, the mainchain plays the role of checkpoint, periodically packaging and recording received transactions from DAGchain for finality. We also provide a prototype implementation with detailed evaluations. Experimental results show our 3D-DAG can meet the performance (a peak value of \(9.82\times 10^{4}\) TPS) that is expected by DApps in the context of Web3.