High-performance BFT consensus for Metaverse through block linking and shortcut loop

In recent years, the Metaverse has captured increasing attention. As the foundational technologies for these digital realms, blockchain systems and their critical component – the Byzantine Fault Tolerance (BFT) consensus protocol – significantly influence the performance of Metaverse. Due to vulnerabilities to network attacks, synchronous and partially synchronous consensus protocols often face compromises in their liveness or security. Consequently, recent efforts in BFT consensus have shifted towards asynchronous consensus protocols, notably the Multi-valued Validated Binary Agreement (MVBA) protocols, with sMVBA being particularly prominent. Despite its advances, sMVBA struggles to meet the high-performance demands of Metaverse applications. Each sMVBA instance commits only one block, discarding all others, which severely restricts throughput. Moreover, if a leader in a given view crashes, nodes must rebroadcast blocks in the subsequent view, resulting in increased latency. To overcome these challenges, this paper introduces Mercury, a protocol designed to enhance throughput under various conditions and reduce latency in less favorable scenarios where leaders are crashed. Mercury incorporates a mechanism whereby each block contains hashes from blocks of a previous instance, linking blocks across instances. This structure ensures that once a block is committed, all its linked blocks are also committed, thereby boosting throughput. Additionally, Mercury integrates a ‘shortcut loop’ mechanism, allowing nodes to bypass the last phase of the current view and the block broadcasting in the next view, significantly decreasing latency. Our experimental evaluations of Mercury confirm its superior performance. Compared to the cutting-edge protocols, sMVBA, CKPS, and AMS, Mercury boosts throughput by 1.03X, 1.65X, and 2.51X, respectively.