Cadence: Extreme Pipelining with Multiple Concurrent Proposers

2026-07-02

AI Summary

Traditional Byzantine fault-tolerant (BFT) consensus protocols are constrained by a single-leader architecture, which limits block intervals due to network latency and exposes the system to censorship and proposal manipulation risks. This work proposes Cadence, a novel BFT protocol that partitions time into equal-length slots and employs an aggressive pipelining design, enabling multiple proposer instances to operate in parallel within each slot. Cadence achieves short-term censorship resistance and proposal confidentiality under a multi-proposer setting—while preserving the low-latency fast path of single-leader protocols—for the first time. Built upon a partially synchronous model, it integrates Chorus slot-based consensus (featuring three-round fast finality and one-round speculative finality) with a Conductor coordinator to form an efficient BFT system. Experiments demonstrate that, with 200 nodes and five proposers per slot, Cadence attains an average finality latency of 219 ms (167 ms for speculative finality), and transactions wait only 50 ms on average before inclusion in a proposal under a 100 ms block interval.

Abstract

We present Cadence, a Byzantine fault-tolerant multi-proposer consensus protocol with arbitrarily low block intervals, optimal resilience, and optimal fast-path latency. Cadence divides time into equally spaced slots, one block per slot, each finalized in its own consensus instance. Blocks do not build directly on their predecessor, so instances run independently and none waits for an earlier block to finish or propagate; we call this extreme pipelining, decoupling the block interval from network latency. Cadence also removes the single-leader monopoly over transaction inclusion and ordering: under multiple concurrent proposers (MCP), several validators propose for each block, and it guarantees that, under synchrony, a transaction a correct proposer includes cannot be censored or deferred (short-term censorship resistance), and that no proposer can craft its proposal in reaction to the others' (hiding). To realize extreme pipelining, we introduce a general framework that turns any one-shot consensus meeting our slot-consensus specification into a multi-shot protocol. We instantiate it for MCP with two protocols of our own: Chorus, a slot consensus whose fast path finalizes a block in an optimal three rounds, with speculative finality one round earlier, and Conductor, an orchestrator that opens slots at an even cadence, more slowly under asynchrony to keep open slots bounded. To our knowledge, Cadence is the first MCP protocol to provide short-term censorship resistance and hiding at the fast-path latency of single-leader consensus. We prove safety, liveness, censorship resistance, and hiding under partial synchrony with optimal resilience (n = 3f+1). In simulation over Monad's 200 validators with five proposers per slot, finalization averages 219 ms (167 ms to speculative finality); at a 100 ms block interval a transaction waits on average 50 ms to enter a proposal.

Problem

• Byzantine fault tolerance
• multi-proposer consensus
• censorship resistance
• extreme pipelining
• block interval

Innovation

• extreme pipelining
• multiple concurrent proposers
• short-term censorship resistance
• hiding
• slot-based consensus