arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2304.14701cs.DC
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无许可共识

Permissionless Consensus

Andrew Lewis-Pye, Tim Roughgarden

AI总结:

本文提出按参与者知识划分的无许可程度层级,刻画区块链共识的能力边界,并证明完全无许可、动态可用和准无许可环境下拜占庭协议、状态机复制及长程攻击的不可能性或可行性结果。

摘要:

区块链协议通常渴望在无许可环境中运行,在该环境中,节点由大量多样化且未知的实体拥有和运营,每个节点都可以随时自由启动或停止运行协议。这一环境比传统的许可环境更具挑战性;在许可环境中,将运行协议的节点集合在协议部署时是固定且已知的。本文的目标是提供一个框架,用于推理区块链协议丰富的设计空间,以及它们在无许可环境中的能力和局限。我们提出了一个具有不同“无许可程度”的环境层级,这些程度由协议对当前参与者所拥有的知识量来规定:它们分别是完全无许可、动态可用和准无许可环境。本文还证明了若干结果,说明我们的分析框架在这些环境中推理区块链协议的效用。例如:(1)在完全无许可环境中,即使通信是同步的,并且对拜占庭参与者的总规模有严格限制,每个用于拜占庭协议的确定性协议都存在一个不终止的执行。(2)在动态可用且部分同步的环境中,任何协议都无法以高概率解决拜占庭协议问题,即使根本不存在拜占庭参与者也是如此。(3)相比之下,在准无许可且部分同步的环境中,假设拜占庭参与者的总规模存在上界,则存在一个解决状态机复制的确定性协议。(4)在准无许可且同步的环境中,每个仅使用时间可延展密码原语的权益证明状态机复制协议都容易受到长程攻击。

英文摘要:

Blockchain protocols typically aspire to run in the permissionless setting, in which nodes are owned and operated by a large number of diverse and unknown entities, with each node free to start or stop running the protocol at any time. This setting is more challenging than the traditional permissioned setting, in which the set of nodes that will be running the protocol is fixed and known at the time of protocol deployment. The goal of this paper is to provide a framework for reasoning about the rich design space of blockchain protocols and their capabilities and limitations in the permissionless setting. We propose a hierarchy of settings with different "degrees of permissionlessness", specified by the amount of knowledge that a protocol has about the current participants: These are the fully permissionless, dynamically available and quasi-permissionless settings. The paper also proves several results illustrating the utility of our analysis framework for reasoning about blockchain protocols in these settings. For example: (1) In the fully permissionless setting, even with synchronous communication and with severe restrictions on the total size of the Byzantine players, every deterministic protocol for Byzantine agreement has a non-terminating execution. (2) In the dynamically available and partially synchronous setting, no protocol can solve the Byzantine agreement problem with high probability, even if there are no Byzantine players at all. (3) In the quasi-permissionless and partially synchronous setting, by contrast, assuming a bound on the total size of the Byzantine players, there is a deterministic protocol solving state machine replication. (4) In the quasi-permissionless and synchronous setting, every proof-of-stake state machine replication protocol that uses only time-malleable cryptographic primitives is vulnerable to long-range attacks.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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