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Documents authored by Danezis, George


Document
BlindPerm: Efficient MEV Mitigation with an Encrypted Mempool and Permutation

Authors: Alireza Kavousi, Duc V. Le, Philipp Jovanovic, and George Danezis

Published in: LIPIcs, Volume 361, 29th International Conference on Principles of Distributed Systems (OPODIS 2025)


Abstract
Maximal Extractable Value (MEV) is a crucial challenge in blockchains and cryptocurrencies. A principal countermeasure is using encrypted mempools to hide the transaction payloads until they are committed in a block. However, the existing approaches based on encrypted mempools remain vulnerable to metadata leakage and may not provide sufficient mitigation against block producers due to their sole control in block preparation. In this paper, we propose techniques that utilize randomized permutation on the committed block, offering a multi-layer solution. With a focus on proof-of-stake (PoS) committee-based consensus, we then introduce BlindPerm, a framework that enhances an encrypted mempool with permutation and present various optimizations. Notably, we propose a construction where this enhancement comes at essentially no overhead by piggybacking on the encrypted mempool and without relying on any external entity such as randomness beacon. Further, we illustrate the effectiveness of our solutions by running simulations using historical Ethereum data.

Cite as

Alireza Kavousi, Duc V. Le, Philipp Jovanovic, and George Danezis. BlindPerm: Efficient MEV Mitigation with an Encrypted Mempool and Permutation. In 29th International Conference on Principles of Distributed Systems (OPODIS 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 361, pp. 36:1-36:21, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)


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@InProceedings{kavousi_et_al:LIPIcs.OPODIS.2025.36,
  author =	{Kavousi, Alireza and Le, Duc V. and Jovanovic, Philipp and Danezis, George},
  title =	{{BlindPerm: Efficient MEV Mitigation with an Encrypted Mempool and Permutation}},
  booktitle =	{29th International Conference on Principles of Distributed Systems (OPODIS 2025)},
  pages =	{36:1--36:21},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-409-3},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{361},
  editor =	{Arusoaie, Andrei and Onica, Emanuel and Spear, Michael and Tucci-Piergiovanni, Sara},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.OPODIS.2025.36},
  URN =		{urn:nbn:de:0030-drops-252091},
  doi =		{10.4230/LIPIcs.OPODIS.2025.36},
  annote =	{Keywords: Encrypted mempool, maximal extractable value, distributed systems}
}
Document
Byzantine Consensus in the Random Asynchronous Model

Authors: George Danezis, Jovan Komatovic, Lefteris Kokoris-Kogias, Alberto Sonnino, and Igor Zablotchi

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


Abstract
We propose a novel relaxation of the classic asynchronous network model, called the random asynchronous model, which removes adversarial message scheduling while preserving unbounded message delays and Byzantine faults. Instead of an adversary dictating message order, delivery follows a random schedule. We analyze Byzantine consensus at different resilience thresholds (n = 3f+1, n = 2f+1, and n = f+2) and show that our relaxation allows consensus with probabilistic guarantees which are impossible in the standard asynchronous model or even the partially synchronous model. We complement these protocols with corresponding impossibility results, establishing the limits of consensus in the random asynchronous model.

Cite as

George Danezis, Jovan Komatovic, Lefteris Kokoris-Kogias, Alberto Sonnino, and Igor Zablotchi. Byzantine Consensus in the Random Asynchronous Model. In 39th International Symposium on Distributed Computing (DISC 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 356, pp. 28:1-28:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)


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@InProceedings{danezis_et_al:LIPIcs.DISC.2025.28,
  author =	{Danezis, George and Komatovic, Jovan and Kokoris-Kogias, Lefteris and Sonnino, Alberto and Zablotchi, Igor},
  title =	{{Byzantine Consensus in the Random Asynchronous Model}},
  booktitle =	{39th International Symposium on Distributed Computing (DISC 2025)},
  pages =	{28:1--28:22},
  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.2025.28},
  URN =		{urn:nbn:de:0030-drops-248457},
  doi =		{10.4230/LIPIcs.DISC.2025.28},
  annote =	{Keywords: network model, asynchronous, random scheduler, Byzantine consensus}
}
Document
Privacy and Security in Smart Energy Grids (Dagstuhl Seminar 16032)

Authors: George Danezis, Stefan Katzenbeisser, Christiane Peters, and Bart Preneel

Published in: Dagstuhl Reports, Volume 6, Issue 1 (2016)


Abstract
This report documents the program and the outcomes of Dagstuhl Seminar 16032 "Privacy and Security in Smart Energy Grids". Smart electricity grids augment the electricity distribution network with modern communications and computerized control to improve efficiency, reliability, and security of electricity distribution, and more flexible production. This initiative has been greeted by consumers and utilities not only with enthusiasm but also concern. Consumers worry about their privacy. Utilities worry about the security of their assets. These outcries and reactions have triggered academics and industry to look into designing privacy friendly architectures for smart metering. The Dagstuhl Seminar 16032 brought together academic researchers as well as utility experts in order to start an open dialogue on smart grid privacy and security problems and potential solutions to support customers and utilities. A particular focus of the seminar were problems related to two timely use-cases for the smart grid, namely smart charging of electric vehicles and distribution automation.

Cite as

George Danezis, Stefan Katzenbeisser, Christiane Peters, and Bart Preneel. Privacy and Security in Smart Energy Grids (Dagstuhl Seminar 16032). In Dagstuhl Reports, Volume 6, Issue 1, pp. 99-107, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2016)


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@Article{danezis_et_al:DagRep.6.1.99,
  author =	{Danezis, George and Katzenbeisser, Stefan and Peters, Christiane and Preneel, Bart},
  title =	{{Privacy and Security in Smart Energy Grids (Dagstuhl Seminar 16032)}},
  pages =	{99--107},
  journal =	{Dagstuhl Reports},
  ISSN =	{2192-5283},
  year =	{2016},
  volume =	{6},
  number =	{1},
  editor =	{Danezis, George and Katzenbeisser, Stefan and Peters, Christiane and Preneel, Bart},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagRep.6.1.99},
  URN =		{urn:nbn:de:0030-drops-58160},
  doi =		{10.4230/DagRep.6.1.99},
  annote =	{Keywords: Critical infrastructure protection, smart energy grids}
}
Document
Improving the Decoding Efficiency of Private Search

Authors: George Danezis and Claudia Diaz

Published in: Dagstuhl Seminar Proceedings, Volume 5411, Anonymous Communication and its Applications (2006)


Abstract
We show two ways of recovering all matching documents, in the Ostrovsky et al. Private Search, while requiring considerably shorter buffers. Both schemes rely on the fact that documents colliding in a buffer position provide the sum of their plaintexts. Efficient decoding algorithms can make use of this property to recover documents never present alone in a buffer position.

Cite as

George Danezis and Claudia Diaz. Improving the Decoding Efficiency of Private Search. In Anonymous Communication and its Applications. Dagstuhl Seminar Proceedings, Volume 5411, pp. 1-11, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2006)


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@InProceedings{danezis_et_al:DagSemProc.05411.3,
  author =	{Danezis, George and Diaz, Claudia},
  title =	{{Improving the Decoding Efficiency of Private Search}},
  booktitle =	{Anonymous Communication and its Applications},
  pages =	{1--11},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2006},
  volume =	{5411},
  editor =	{Shlomi Dolev and Rafail Ostrovsky and Andreas Pfitzmann},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.05411.3},
  URN =		{urn:nbn:de:0030-drops-4829},
  doi =		{10.4230/DagSemProc.05411.3},
  annote =	{Keywords: Private search, private information retrieval, cryptography}
}
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