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Documents authored by Meling, Hein

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)

Copy BibTex To Clipboard

@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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