arXiv subjects

Florian Suri-Payer

Publications and source records attributed to Florian Suri-Payer.

5 recordsLinked to original sources

arXiv2026

Sintr: Safe Interactive Transactions in the Presence of Byzantine Clients

Byzantine fault-tolerant (BFT) systems are, in principle, an appealing foundation for transactional applications involving mutually distrustful participants. Yet their adoption has been hampered by two persistent stumbling blocks-performance and developer convenience-which are often in tension with one another. Recent systems show promising progress on both fronts by shifting to a client-centric architecture; clients execute transactions locally and concurrently, while the system resolves any data conflicts to maintain database serializability. We argue that, in its current form, this approach introduces a critical vulnerability: it leaves the integrity of the database exposed to Byzantine clients, which may issue malicious or incorrect transactions. We address this threat with Sintr, a framework that prevents Byzantine clients from compromising database integrity by executing rogue transactions. Sintr combines redundant execution to validate transaction outcomes with a flexible, heterogeneous policy framework for expressing an application's data-integrity requirements. We apply Sintr to harden several existing BFT database systems and find that it imposes only modest overheads-3%-16% in throughput and 3%-21% in latency.

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arXiv2025

Shoal++: High Throughput DAG BFT Can Be Fast!

Today's practical partially synchronous Byzantine Fault Tolerant (BFT) consensus protocols trade off low latency and high throughput. On the one end, traditional BFT protocols such as PBFT and its derivatives optimize for latency. They require, in fault-free executions, only 3 message exchanges to commit, the optimum for BFT consensus. However, this class of protocols typically relies on a single leader, hampering throughput scalability. On the other end, a new class of so-called DAG-BFT protocols demonstrates how to achieve highly scalable throughput by separating data dissemination from consensus, and using every replica as proposer. Unfortunately, existing DAG-BFT protocols pay a steep latency premium, requiring on average 10.5 message exchanges to commit a transactions. This work aims to soften this tension and proposes Shoal++, a novel DAG-based BFT consensus system that offers the throughput of DAGs while reducing commit latency to an average of 4.5 message exchanges. Our empirical findings are encouraging, showing that Shoal++ achieves throughput comparable to state-of-the-art DAG BFT solutions while reducing latency by up to 60%.

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arXiv2025

Autobahn: Seamless high speed BFT

Today's practical, high performance Byzantine Fault Tolerant (BFT) consensus protocols operate in the partial synchrony model. However, existing protocols are inefficient when deployments are indeed partially synchronous. They deliver either low latency during fault-free, synchronous periods (good intervals) or robust recovery from events that interrupt progress (blips). At one end, traditional, view-based BFT protocols optimize for latency during good intervals, but, when blips occur, can suffer from performance degradation (hangovers) that can last beyond the return of a good interval. At the other end, modern DAG-based BFT protocols recover more gracefully from blips, but exhibit lackluster latency during good intervals. To close the gap, this work presents Autobahn, a novel high-throughput BFT protocol that offers both low latency and seamless recovery from blips. By combining a highly parallel asynchronous data dissemination layer with a low-latency, partially synchronous consensus mechanism, Autobahn (i) avoids the hangovers incurred by traditional BFT protocols and (ii) matches the throughput of state of the art DAG-based BFT protocols while cutting their latency in half, matching the latency of traditional BFT protocols.

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arXiv2023

BeeGees: stayin' alive in chained BFT

Modern chained Byzantine Fault Tolerant (BFT) systems leverage a combination of pipelining and leader rotation to obtain both efficiency and fairness. These protocols, however, require a sequence of three or four consecutive honest leaders to commit operations. Therefore, even simple leader failures such as crashes can weaken liveness both theoretically and practically. Obtaining a chained BFT protocol that reaches decisions even if the sequence of honest leaders is non-consecutive, remains an open question. To resolve this question we present BeeGees, a novel chained BFT protocol that successfully commits blocks even with non-consecutive honest leaders. It does this while also maintaining quadratic word complexity with threshold signatures, linear word complexity with SNARKs, and responsiveness between consecutive honest leaders. BeeGees reduces the expected commit latency of HotStuff by a factor of three under failures, and the worst-case latency by a factor of seven.

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arXiv2021

Basil: Breaking up BFT with ACID (transactions)

This paper presents Basil, the first transactional, leaderless Byzantine Fault Tolerant key-value store. Basil leverages ACID transactions to scalably implement the abstraction of a trusted shared log in the presence of Byzantine actors. Unlike traditional BFT approaches, Basil executes non-conflicting operations in parallel and commits transactions in a single round-trip during fault-free executions. Basil improves throughput over traditional BFT systems by four to five times, and is only four times slower than TAPIR, a non-Byzantine replicated system. Basil's novel recovery mechanism further minimizes the impact of failures: with 30% Byzantine clients, throughput drops by less than 25% in the worst-case.

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