TaiJi: Longest Chain Availability with BFT Fast Confirmation
TaiJi: Longest Chain Availability with BFT Fast Confirmation
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TaiJi：最长链可用性和BFT快速确认
DOI：
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发表时间：
2020
期刊：
影响因子：
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通讯作者：
David Tse
中科院分区：
文献类型：
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作者：
Songze Li;David Tse
大多数状态机复制协议要么基于已有40年历史的拜占庭容错(BFT)理论，要么基于较新的Nakamoto最长链设计。最长链协议最初设计在工作验证(PoW)设置中，在动态参与下可用，但具有概率确认，延迟时间较长，具体取决于安全参数。针对许可设置设计的BFT协议具有快速确定性确认，但假设固定数量的节点始终在线。我们提出了一种新的结构，它结合了最长链协议和BFT协议，以达到两全其美的效果。利用这种构造，我们设计了第一个动态可用的PoW协议--太极，它具有几乎确定性的确认，并且延迟与安全参数无关。与以前的混合方法使用单个最长链来采样参与者来运行BFT协议不同，我们的本地POW构造使用许多独立的最长链来采样BFT协议的提议动作和投票动作。这种设计使太极继承了比特币的完全动态可用性以及完全的不可预测性，使其能够安全地抵御具有高达50%在线哈希能力的完全自适应的对手。
Most state machine replication protocols are either based on the 40-years-old Byzantine Fault Tolerance (BFT) theory or the more recent Nakamoto's longest chain design. Longest chain protocols, designed originally in the Proof-of-Work (PoW) setting, are available under dynamic participation, but has probabilistic confirmation with long latency dependent on the security parameter. BFT protocols, designed for the permissioned setting, has fast deterministic confirmation, but assume a fixed number of nodes always online. We present a new construction which combines a longest chain protocol and a BFT protocol to get the best of both worlds. Using this construction, we design TaiJi, the first dynamically available PoW protocol which has almost deterministic confirmation with latency independent of the security parameter. In contrast to previous hybrid approaches which use a single longest chain to sample participants to run a BFT protocol, our native PoW construction uses many independent longest chains to sample propose actions and vote actions for the BFT protocol. This design enables TaiJi to inherit the full dynamic availability of Bitcoin, as well as its full unpredictability, making it secure against fully-adaptive adversaries with up to 50% of online hash power.