4 Search Results for "Meling, Hein"

Document
DOI: 10.4230/LIPIcs.DISC.2025.39
TEE Is Not a Healer: Rollback-Resistant Reliable Storage

Authors: Sadegh Keshavarzi, Gregory Chockler, and Alexey Gotsman

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

Abstract
Recent advances in secure hardware technologies, such as Intel SGX or ARM TrustZone, offer an opportunity to substantially reduce the costs of Byzantine fault-tolerance by placing the program code and state within a secure enclave known as a Trusted Execution Environment (TEE). However, the protection offered by a TEE only applies during program execution. Once power is switched off, the non-volatile portion of the program state becomes vulnerable to rollback attacks wherein it is undetectably reverted to an older version. In this paper we consider the problem of implementing reliable read/write registers out of failure-prone replicas subject to state rollbacks. To this end, we introduce a new unified model that captures multiple failure types that can affect a TEE-based system and establish tight bounds on the fault-tolerance of register constructions in this model. We consider both the static case, where failure thresholds hold throughout the entire execution, and the dynamic case, where any number of replicas can roll back, provided these failures do not occur too often. Our dynamic register emulation algorithm, TEE-Rex , provides the first correct implementation of a distributed state recovery procedure that requires neither durable storage nor specialized hardware, such as trusted monotonic counters.
Cite as

Sadegh Keshavarzi, Gregory Chockler, and Alexey Gotsman. TEE Is Not a Healer: Rollback-Resistant Reliable Storage. In 39th International Symposium on Distributed Computing (DISC 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 356, pp. 39:1-39:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@InProceedings{keshavarzi_et_al:LIPIcs.DISC.2025.39,
  author =	{Keshavarzi, Sadegh and Chockler, Gregory and Gotsman, Alexey},
  title =	{{TEE Is Not a Healer: Rollback-Resistant Reliable Storage}},
  booktitle =	{39th International Symposium on Distributed Computing (DISC 2025)},
  pages =	{39:1--39:18},
  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.2025.39},
  URN =		{urn:nbn:de:0030-drops-248560},
  doi =		{10.4230/LIPIcs.DISC.2025.39},
  annote =	{Keywords: Trusted execution environments, fault tolerance, crash recovery}
}
Document
DOI: 10.4230/LIPIcs.AFT.2025.18
From Permissioned to Proof-of-Stake Consensus

Authors: Jovan Komatovic, Andrew Lewis-Pye, Joachim Neu, Tim Roughgarden, and Ertem Nusret Tas

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

Abstract
This paper presents the first generic compiler that transforms any permissioned consensus protocol into a proof-of-stake permissionless consensus protocol. For each of the following properties, if the initial permissioned protocol satisfies that property in the partially synchronous setting, the consequent proof-of-stake protocol also satisfies that property in the partially synchronous and quasi-permissionless setting (with the same fault-tolerance): consistency; liveness; optimistic responsiveness; every composable log-specific property; and message complexity of a given order. Moreover, our transformation ensures that the output protocol satisfies accountability (identifying culprits in the event of a consistency violation), whether or not the original permissioned protocol satisfied it.
Cite as

Jovan Komatovic, Andrew Lewis-Pye, Joachim Neu, Tim Roughgarden, and Ertem Nusret Tas. From Permissioned to Proof-of-Stake Consensus. In 7th Conference on Advances in Financial Technologies (AFT 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 354, pp. 18:1-18:26, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@InProceedings{komatovic_et_al:LIPIcs.AFT.2025.18,
  author =	{Komatovic, Jovan and Lewis-Pye, Andrew and Neu, Joachim and Roughgarden, Tim and Tas, Ertem Nusret},
  title =	{{From Permissioned to Proof-of-Stake Consensus}},
  booktitle =	{7th Conference on Advances in Financial Technologies (AFT 2025)},
  pages =	{18:1--18:26},
  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.2025.18},
  URN =		{urn:nbn:de:0030-drops-247373},
  doi =		{10.4230/LIPIcs.AFT.2025.18},
  annote =	{Keywords: Permissioned Consensus, Proof-of-Stake, generic Compiler, Blockchain}
}
Document
DOI: 10.4230/LIPIcs.OPODIS.2022.9
A Privacy-Preserving and Transparent Certification System for Digital Credentials

Authors: Rodrigo Q. Saramago, Hein Meling, and Leander N. Jehl

Published in: LIPIcs, Volume 253, 26th International Conference on Principles of Distributed Systems (OPODIS 2022)

Abstract
A certification system is responsible for issuing digital credentials, which attest claims about a subject, e.g., an academic diploma. Such credentials are valuable for individuals and society, and widespread adoption requires a trusted certification system. Trust can be gained by being transparent when issuing and verifying digital credentials. However, there is a fundamental tradeoff between privacy and transparency. For instance, admitting a student to an academic program must preserve the student’s privacy, i.e., the student’s grades must not be revealed to unauthorized parties. At the same time, other applicants may demand transparency to ensure fairness in the admission process. Thus, building a certification system with the right balance between privacy and transparency is challenging. This paper proposes a novel design for a certification system that provides sufficient transparency and preserves privacy through selective disclosure of claims such that authorized parties can verify them. Moreover, unauthorized parties can also verify the correctness of the certification process without compromising privacy. We achieve this using an incremental Merkle tree of cryptographic commitments to users' credentials. The commitments are added to the tree based on verifying zero-knowledge issuance proofs. Users store credentials off-chain and can prove the ownership and authenticity of credentials without revealing their commitments. Further, our approach enables users to prove statements about the credential’s claims in zero-knowledge. Our design offers a cost-efficient solution, reducing the amount of linkable on-chain data by up to 79% per credential compared to prior work, while maintaining transparency.
Cite as

Rodrigo Q. Saramago, Hein Meling, and Leander N. Jehl. A Privacy-Preserving and Transparent Certification System for Digital Credentials. In 26th International Conference on Principles of Distributed Systems (OPODIS 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 253, pp. 9:1-9:24, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)

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@InProceedings{saramago_et_al:LIPIcs.OPODIS.2022.9,
  author =	{Saramago, Rodrigo Q. and Meling, Hein and Jehl, Leander N.},
  title =	{{A Privacy-Preserving and Transparent Certification System for Digital Credentials}},
  booktitle =	{26th International Conference on Principles of Distributed Systems (OPODIS 2022)},
  pages =	{9:1--9:24},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-265-5},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{253},
  editor =	{Hillel, Eshcar and Palmieri, Roberto and Rivi\`{e}re, Etienne},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.OPODIS.2022.9},
  URN =		{urn:nbn:de:0030-drops-176294},
  doi =		{10.4230/LIPIcs.OPODIS.2022.9},
  annote =	{Keywords: verifiable credentials, privacy-preserving, zero-knowledge, blockchain}
}
Document
DOI: 10.4230/LIPIcs.OPODIS.2016.31
The Case for Reconfiguration without Consensus: Comparing Algorithms for Atomic Storage

Authors: Leander Jehl and Hein Meling

Published in: LIPIcs, Volume 70, 20th International Conference on Principles of Distributed Systems (OPODIS 2016)

Abstract
We compare different algorithms for reconfigurable atomic storage in the data-centric model. We present the first experimental evaluation of two recently proposed algorithms for reconfiguration without consensus and compare them to established algorithms for reconfiguration both with and without consensus. Our evaluation reveals that the new algorithms offer a significant improvement in terms of latency and overhead for reconfiguration without consensus. Our evaluation also shows that reconfiguration without consensus, can obtain similar results to that of consensus-based reconfiguration, which relies on a stable leader. Moreover, the new algorithms also substantially reduces the overhead compared to consensus-based reconfiguration without a leader. While our analysis confirms our intuition that batching reconfiguration requests serves to reduce the overhead of reconfigurations, our evaluation also shows that it is equally important to separate reconfigurations from read and write operations. Specifically, we found that using read and write operations to assist in completing concurrent reconfigurations is in fact detrimental to the reconfiguration performance.
Cite as

Leander Jehl and Hein Meling. The Case for Reconfiguration without Consensus: Comparing Algorithms for Atomic Storage. In 20th International Conference on Principles of Distributed Systems (OPODIS 2016). Leibniz International Proceedings in Informatics (LIPIcs), Volume 70, pp. 31:1-31:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2017)

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@InProceedings{jehl_et_al:LIPIcs.OPODIS.2016.31,
  author =	{Jehl, Leander and Meling, Hein},
  title =	{{The Case for Reconfiguration without Consensus: Comparing Algorithms for Atomic Storage}},
  booktitle =	{20th International Conference on Principles of Distributed Systems (OPODIS 2016)},
  pages =	{31:1--31:17},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-031-6},
  ISSN =	{1868-8969},
  year =	{2017},
  volume =	{70},
  editor =	{Fatourou, Panagiota and Jim\'{e}nez, Ernesto and Pedone, Fernando},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.OPODIS.2016.31},
  URN =		{urn:nbn:de:0030-drops-71006},
  doi =		{10.4230/LIPIcs.OPODIS.2016.31},
  annote =	{Keywords: atomic storage, reconfiguration, data-centric model}
}
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