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DOI: 10.4230/LIPIcs.DISC.2025.42

Kudzu: Fast and Simple High-Throughput BFT

Authors: Victor Shoup, Jakub Sliwinski, and Yann Vonlanthen

Published in: LIPIcs, Volume 356, 39th International Symposium on Distributed Computing (DISC 2025)

Abstract

We present Kudzu, a high-throughput atomic broadcast protocol with an integrated fast path. Our contribution is based on the combination of two lines of work. Firstly, our protocol achieves finality in just two rounds of communication if all but p out of n = 3f + 2p + 1 participating replicas behave correctly, where f is the number of Byzantine faults that are tolerated. Due to the seamless integration of the fast path, even in the presence of more than p faults, our protocol maintains state-of-the-art characteristics. Secondly, our protocol utilizes the bandwidth of participating replicas in a balanced way, alleviating the bottleneck at the leader, and thus enabling high throughput. This is achieved by disseminating blocks using erasure codes. Despite combining a novel set of advantages, Kudzu is remarkably simple: intricacies such as "progress certificates", complex view changes, and speculative execution are avoided.

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Victor Shoup, Jakub Sliwinski, and Yann Vonlanthen. Kudzu: Fast and Simple High-Throughput BFT. In 39th International Symposium on Distributed Computing (DISC 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 356, pp. 42:1-42:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@InProceedings{shoup_et_al:LIPIcs.DISC.2025.42,
  author =	{Shoup, Victor and Sliwinski, Jakub and Vonlanthen, Yann},
  title =	{{Kudzu: Fast and Simple High-Throughput BFT}},
  booktitle =	{39th International Symposium on Distributed Computing (DISC 2025)},
  pages =	{42:1--42:19},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-402-4},
  ISSN =	{1868-8969},
  year =	{2025},
  volume =	{356},
  editor =	{Kowalski, Dariusz R.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.DISC.2025.42},
  URN =		{urn:nbn:de:0030-drops-248597},
  doi =		{10.4230/LIPIcs.DISC.2025.42},
  annote =	{Keywords: Consensus, Blockchain, Byzantine Fault Tolerance, Fast Path, State Machine Replication}
}

Document

DOI: 10.4230/LIPIcs.AFT.2025.28

Optimistic MEV in Ethereum Layer 2s: Why Blockspace Is Always in Demand

Authors: Ozan Solmaz, Lioba Heimbach, Yann Vonlanthen, and Roger Wattenhofer

Published in: LIPIcs, Volume 354, 7th Conference on Advances in Financial Technologies (AFT 2025)

Abstract

Layer 2 rollups are rapidly absorbing DeFi activity, securing over $40 billion and accounting for nearly half of Ethereum’s DEX volume by Q1 2025, yet their MEV dynamics remain understudied. We address this gap by defining and quantifying optimistic MEV, a form of speculative, on-chain MEV whose detection and execution logic reside largely on-chain in smart contracts. As a result of their speculative nature and lack of off-chain opportunity verification, optimistic MEV transactions frequently decide not to execute any trades. In this work, we focus on cyclic arbitrage, which we find is predominantly executed as optimistic MEV on Layer 2s. Using our multi-stage identification pipeline on Arbitrum, Base, and Optimism, we show that in Q1 2025, transactions from cyclic arbitrage contracts account for over 50% of on-chain gas on Base and Optimism and 7% on Arbitrum, driven mainly by "interaction" probes (on-chain computations searching for arbitrage). This speculative probing indicates that cyclic arbitrage on Layer 2s is predominantly executed as optimistic MEV and contributes to generally keeping blocks on Base and Optimism persistently full. Despite consuming over half of on-chain gas, these optimistic MEV transactions pay less than one quarter of total gas fees. Cross-network comparison reveals divergent success rates, differing patterns of code reuse, and sensitivity to varying sequencer ordering and block production times. Finally, OLS regressions link optimistic MEV trade count to ETH volatility, retail trading activity, and DEX aggregator usage. Together, these findings show that optimistic MEV has become a major source of persistent spam-like transaction activity on Layer 2s, dominating blockspace with low-value probes and reshaping the composition of on-chain activity.

Cite as

Ozan Solmaz, Lioba Heimbach, Yann Vonlanthen, and Roger Wattenhofer. Optimistic MEV in Ethereum Layer 2s: Why Blockspace Is Always in Demand. In 7th Conference on Advances in Financial Technologies (AFT 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 354, pp. 28:1-28:24, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@InProceedings{solmaz_et_al:LIPIcs.AFT.2025.28,
  author =	{Solmaz, Ozan and Heimbach, Lioba and Vonlanthen, Yann and Wattenhofer, Roger},
  title =	{{Optimistic MEV in Ethereum Layer 2s: Why Blockspace Is Always in Demand}},
  booktitle =	{7th Conference on Advances in Financial Technologies (AFT 2025)},
  pages =	{28:1--28:24},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-400-0},
  ISSN =	{1868-8969},
  year =	{2025},
  volume =	{354},
  editor =	{Avarikioti, Zeta and Christin, Nicolas},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.AFT.2025.28},
  URN =		{urn:nbn:de:0030-drops-247479},
  doi =		{10.4230/LIPIcs.AFT.2025.28},
  annote =	{Keywords: blockchain, MEV, Layer 2, Ethereum}
}

Document

DOI: 10.4230/LIPIcs.AFT.2024.28

SoK: Attacks on DAOs

Authors: Rainer Feichtinger, Robin Fritsch, Lioba Heimbach, Yann Vonlanthen, and Roger Wattenhofer

Published in: LIPIcs, Volume 316, 6th Conference on Advances in Financial Technologies (AFT 2024)

Abstract

Decentralized Autonomous Organizations (DAOs) are blockchain-based organizations that facilitate decentralized governance. Today, DAOs not only hold billions of dollars in their treasury but also govern many of the most popular Decentralized Finance (DeFi) protocols. This paper systematically analyses security threats to DAOs, focusing on the types of attacks they face. We study attacks on DAOs that took place in the past, attacks that have been theorized to be possible, and potential attacks that were uncovered and prevented in audits. For each of these (potential) attacks, we describe and categorize the attack vectors utilized into four categories. This reveals that while many attacks on DAOs take advantage of the less tangible and more complex human nature involved in governance, audits tend to focus on code and protocol vulnerabilities. Thus, additionally, the paper examines empirical data on DAO vulnerabilities, outlines risk factors contributing to these attacks, and suggests mitigation strategies to safeguard against such vulnerabilities.

Cite as

Rainer Feichtinger, Robin Fritsch, Lioba Heimbach, Yann Vonlanthen, and Roger Wattenhofer. SoK: Attacks on DAOs. In 6th Conference on Advances in Financial Technologies (AFT 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 316, pp. 28:1-28:27, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{feichtinger_et_al:LIPIcs.AFT.2024.28,
  author =	{Feichtinger, Rainer and Fritsch, Robin and Heimbach, Lioba and Vonlanthen, Yann and Wattenhofer, Roger},
  title =	{{SoK: Attacks on DAOs}},
  booktitle =	{6th Conference on Advances in Financial Technologies (AFT 2024)},
  pages =	{28:1--28:27},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-345-4},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{316},
  editor =	{B\"{o}hme, Rainer and Kiffer, Lucianna},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.AFT.2024.28},
  URN =		{urn:nbn:de:0030-drops-209640},
  doi =		{10.4230/LIPIcs.AFT.2024.28},
  annote =	{Keywords: blockchain, DAO, governance, security, measurements, voting systems}
}

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Documents authored by Vonlanthen, Yann

Kudzu: Fast and Simple High-Throughput BFT

Abstract

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Optimistic MEV in Ethereum Layer 2s: Why Blockspace Is Always in Demand

Abstract

Cite as

SoK: Attacks on DAOs

Abstract

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