arXiv subjects

Daniel Cason

Publications and source records attributed to Daniel Cason.

3 recordsLinked to original sources

arXiv2026

Fast Tendermint: Speeding Up a Foundational Consensus Protocol

Tendermint is among the most widely studied and deployed Byzantine fault-tolerant (BFT) consensus protocols, owing in part to its native leader-rotation mechanism that subsumes complex view changes. Like most partially-synchronous BFT protocols, Tendermint tolerates $f < n/3$ Byzantine processes and decides in three communication steps. Motivated by the push for lower-latency blockchains, a recent line of work shows that consensus can be solved in two communication steps when $f < n/5$. We present Fast Tendermint, an adaptation of Tendermint to the $n > 5f$ setting that decides in two communication steps in the good case, while preserving Tendermint's leader-rotation structure. Fast Tendermint collapses Tendermint's prevote and precommit steps into a single voting step and merges the $locked$ and $valid$ state. We give proofs of agreement, validity, and termination, and a formal specification in Quint, a modern surface syntax for TLA+, used to model-check the protocol.

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arXiv2026

AMP: Arc Multi-Proposer Protocol with Bounded Inclusion Guarantees

Blockchain systems that settle financial transactions face a structural tension: the single validator that assembles each block holds unilateral power over transaction inclusion and ordering. Traditional markets curb this very power through front-running and market-manipulation laws. Regulators have flagged the absence of such rules as a first-order concern for blockchain-based financial infrastructure. In response, we introduce AMP, a multi-proposer protocol, on top of the Tendermint consensus algorithm, where no validator can control the flow of transactions into blocks. Instead, dedicated nodes called proposers sit between users and validators. They collect user transactions, group them into payloads, and broadcast the payloads to all validators. Consequently, there is no mempool, and AMP applies the design principle of separating dissemination from agreement, which can lead to higher throughput. Validators publicly attest to receiving payloads and run consensus to decide the set of payloads to include in the next block. When all correct validators attest to a given payload, AMP guarantees that payload will be included in the next block; a block thus contains payloads from multiple proposers, allowing for bulk finalization. This bounded inclusion guarantee along with a deterministic ordering algorithm which is run over all payloads included in a block, curbs the power of any single validator. Validators no longer control what is included in a block, nor can they arbitrarily order the contents of blocks.

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arXiv2025

Message Size Matters: AlterBFT's Approach to Practical Synchronous BFT in Public Clouds

Synchronous consensus protocols offer a significant advantage over their asynchronous and partially synchronous counterparts by providing higher fault tolerance -- an essential benefit in distributed systems, like blockchains, where participants may have incentives to act maliciously. However, despite this advantage, synchronous protocols are often met with skepticism due to concerns about their performance, as the latency of synchronous protocols is tightly linked to a conservative time bound for message delivery. This paper introduces AlterBFT, a new Byzantine fault-tolerant consensus protocol. The key idea behind AlterBFT lies in the new model we propose, called hybrid synchronous system model. The new model is inspired by empirical observations about network behavior in the public cloud environment and combines elements from the synchronous and partially synchronous models. Namely, it distinguishes between small messages that respect time bounds and large messages that may violate bounds but are eventually timely. Leveraging this observation, AlterBFT achieves up to 15$\times$ lower latency than state-of-the-art synchronous protocols while maintaining similar throughput and the same fault tolerance. Compared to partially synchronous protocols, AlterBFT provides higher fault tolerance, higher throughput, and comparable latency.

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