arXiv:2607.21021 · v6

Multimmit: Extending Blocks for Faster Finality

首次提交 2026-07-23 16:05

版本更新 2026-11-13 00:52

雷达观测 2026-11-13 14:15

摘要

To meet the throughput demands of blockchain systems, protocols for State Machine Replication increasingly have many processors disseminate transaction blocks in parallel. Certified designs require availability certificates before blocks enter the ordering process, which is robust but adds latency. BlueBottle, the leading uncertified design under $n\geq 5f+1$ ($n$ processors, at most $f$ Byzantine), reduces latency in favourable conditions but can put fetching missing data on the critical path. Raptr, the state of the art under $n\geq 3f+1$, avoids fetching on the voting path, but transactions wait for a leader's proposal and two voting rounds, and the leader controls the proposed sequence. We prove that strengthening the resilience assumption alone cannot remove Raptr's second voting round. We present Multimmit, a protocol for $n\geq 5f+1$ that builds on Raptr's approach and finalises leader blocks after a single round of voting, improving latency by at least one message delay. Extension votes let voters endorse fresh transaction blocks omitted from the leader's proposal: once a leader block finalises, every fresh, well-circulated block of an honest chain enters the total ordering by the next finalised leader block, even if that block's leader is Byzantine. Producer chains are interleaved by a prescribed rule, not in a leader-chosen sequence. Payments are final within a single round trip, once the producer assembles $n-f$ acknowledgments into a transferable receipt. With fifty validators across thirteen regions, Multimmit's median latency to placement in the total ordering moves from 383 to 411 ms as the offered rate rises from 100k to 1M transactions per second. At 100k, it is essentially unchanged under 0.1% message loss and rises by a factor of 1.4 with nine validators crashed; these conditions slow BlueBottle and Raptr, respectively, by more than an order of magnitude.