13 Search Results for "Steinwandt, Rainer"

Document
DOI: 10.4230/LIPIcs.ITCS.2026.23
Decoding Balanced Linear Codes with Preprocessing

Authors: Andrej Bogdanov, Rohit Chatterjee, Yunqi Li, and Prashant Nalini Vasudevan

Published in: LIPIcs, Volume 362, 17th Innovations in Theoretical Computer Science Conference (ITCS 2026)

Abstract
Prange’s information set algorithm is a well-known decoding algorithm for linear codes. It decodes corrupted codewords of most 𝔽₂-linear codes C of message length n up to relative error rate O(log n / n) in poly(n) time. We show that the error rate can be improved to O((log n)² / n), provided: (1) the decoder has access to a polynomial-length advice string that depends on C only, and (2) C is n^{-Ω(1)}-balanced. As a consequence we improve the error tolerance in decoding random linear codes if inefficient preprocessing of the code is allowed. This reveals potential vulnerabilities in cryptographic applications of Learning Noisy Parities with low noise rate. Our main technical result is that the Hamming weight of Hw, where the rows of H are a random sample of short dual codewords, measures the proximity of a received word w to the code in the regime of interest. Given such H as advice, our algorithm corrects errors by locally minimizing this measure. We show that for most codes, the error rate tolerated by our decoder is asymptotically optimal among all algorithms whose decision is based on thresholding Hw for an arbitrary polynomial-size advice matrix H.
Cite as

Andrej Bogdanov, Rohit Chatterjee, Yunqi Li, and Prashant Nalini Vasudevan. Decoding Balanced Linear Codes with Preprocessing. In 17th Innovations in Theoretical Computer Science Conference (ITCS 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 362, pp. 23:1-23:23, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

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@InProceedings{bogdanov_et_al:LIPIcs.ITCS.2026.23,
  author =	{Bogdanov, Andrej and Chatterjee, Rohit and Li, Yunqi and Vasudevan, Prashant Nalini},
  title =	{{Decoding Balanced Linear Codes with Preprocessing}},
  booktitle =	{17th Innovations in Theoretical Computer Science Conference (ITCS 2026)},
  pages =	{23:1--23:23},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-410-9},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{362},
  editor =	{Saraf, Shubhangi},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ITCS.2026.23},
  URN =		{urn:nbn:de:0030-drops-253107},
  doi =		{10.4230/LIPIcs.ITCS.2026.23},
  annote =	{Keywords: Linear codes, nearest codeword problem, learning parity with noise}
}
Document
DOI: 10.4230/DagRep.13.10.65
Quantum Cryptanalysis (Dagstuhl Seminar 23421)

Authors: Gorjan Alagic, Maria Naya-Plasencia, Rainer Steinwandt, and Manasi Shingane

Published in: Dagstuhl Reports, Volume 13, Issue 10 (2024)

Abstract
This report documents the program and the outcomes of Dagstuhl Seminar 23421 "Quantum Cryptanalysis". The seminar took place as an in-person event in October 2023 and was the seventh installment of the Dagstuhl Seminar series on Quantum Cryptanalysis. This report describes the motivation and technical scope of the seminar as well as the (updated) organizational structure of this week-long event. We also include abstracts of the seminar presentations given by participants and a description of the activities of the working groups.
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Gorjan Alagic, Maria Naya-Plasencia, Rainer Steinwandt, and Manasi Shingane. Quantum Cryptanalysis (Dagstuhl Seminar 23421). In Dagstuhl Reports, Volume 13, Issue 10, pp. 65-75, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@Article{alagic_et_al:DagRep.13.10.65,
  author =	{Alagic, Gorjan and Naya-Plasencia, Maria and Steinwandt, Rainer and Shingane, Manasi},
  title =	{{Quantum Cryptanalysis (Dagstuhl Seminar 23421)}},
  pages =	{65--75},
  journal =	{Dagstuhl Reports},
  ISSN =	{2192-5283},
  year =	{2024},
  volume =	{13},
  number =	{10},
  editor =	{Alagic, Gorjan and Naya-Plasencia, Maria and Steinwandt, Rainer and Shingane, Manasi},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagRep.13.10.65},
  URN =		{urn:nbn:de:0030-drops-198345},
  doi =		{10.4230/DagRep.13.10.65},
  annote =	{Keywords: computational algebra, cryptanalysis, post-quantum cryptography, quantum algorithms, quantum resource estimation}
}
Document
DOI: 10.4230/DagRep.11.9.64
Quantum Cryptanalysis (Dagstuhl Seminar 21421)

Authors: Stacey Jeffery, Michele Mosca, Maria Naya-Plasencia, and Rainer Steinwandt

Published in: Dagstuhl Reports, Volume 11, Issue 9 (2022)

Abstract
This seminar report documents the program and the outcomes of Dagstuhl Seminar 21421 Quantum Cryptanalysis. The seminar took place in a hybrid format in Fall 2021. The report starts out with the motivation and comments on the organization of this instance of the Dagstuhl Seminar series on {Quantum Cryptanalysis}, followed by abstracts of presentations. The presentation abstracts were provided by seminar participants.
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Stacey Jeffery, Michele Mosca, Maria Naya-Plasencia, and Rainer Steinwandt. Quantum Cryptanalysis (Dagstuhl Seminar 21421). In Dagstuhl Reports, Volume 11, Issue 9, pp. 64-79, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)

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@Article{jeffery_et_al:DagRep.11.9.64,
  author =	{Jeffery, Stacey and Mosca, Michele and Naya-Plasencia, Maria and Steinwandt, Rainer},
  title =	{{Quantum Cryptanalysis (Dagstuhl Seminar 21421)}},
  pages =	{64--79},
  journal =	{Dagstuhl Reports},
  ISSN =	{2192-5283},
  year =	{2022},
  volume =	{11},
  number =	{9},
  editor =	{Jeffery, Stacey and Mosca, Michele and Naya-Plasencia, Maria and Steinwandt, Rainer},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagRep.11.9.64},
  URN =		{urn:nbn:de:0030-drops-159187},
  doi =		{10.4230/DagRep.11.9.64},
  annote =	{Keywords: computational algebra, post-quantum cryptography, quantum computing, quantum resource estimation}
}
Document
DOI: 10.4230/DagRep.9.10.47
Quantum Cryptanalysis (Dagstuhl Seminar 19421)

Authors: Michele Mosca, Maria Naya-Plasencia, and Rainer Steinwandt

Published in: Dagstuhl Reports, Volume 9, Issue 10 (2020)

Abstract
This seminar report documents the program and the outcomes of Dagstuhl Seminar 19421 "Quantum Cryptanalysis", which took place in October 2019. After outlining the motivation and organizational aspects of this particular seminar, abstracts of presentations that were given by participants are provided.
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Michele Mosca, Maria Naya-Plasencia, and Rainer Steinwandt. Quantum Cryptanalysis (Dagstuhl Seminar 19421). In Dagstuhl Reports, Volume 9, Issue 10, pp. 47-60, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)

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@Article{mosca_et_al:DagRep.9.10.47,
  author =	{Mosca, Michele and Naya-Plasencia, Maria and Steinwandt, Rainer},
  title =	{{Quantum Cryptanalysis (Dagstuhl Seminar 19421)}},
  pages =	{47--60},
  journal =	{Dagstuhl Reports},
  ISSN =	{2192-5283},
  year =	{2020},
  volume =	{9},
  number =	{10},
  editor =	{Mosca, Michele and Naya-Plasencia, Maria and Steinwandt, Rainer},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagRep.9.10.47},
  URN =		{urn:nbn:de:0030-drops-118543},
  doi =		{10.4230/DagRep.9.10.47},
  annote =	{Keywords: computational algebra, post-quantum cryptography, quantum circuit complexity, quantum computing, standardization}
}
Document
DOI: 10.4230/DagRep.7.10.1
Quantum Cryptanalysis (Dagstuhl Seminar 17401)

Authors: Michele Mosca, Nicolas Sendrier, Rainer Steinwandt, and Krysta Svore

Published in: Dagstuhl Reports, Volume 7, Issue 10 (2018)

Abstract
This report documents the program and the outcomes of Dagstuhl Seminar 17401 "Quantum Cryptanalysis." We start out by outlining the motivation and organizational aspects of the seminar. Thereafter, abstracts of presentations given by seminar participants are provided.
Cite as

Michele Mosca, Nicolas Sendrier, Rainer Steinwandt, and Krysta Svore. Quantum Cryptanalysis (Dagstuhl Seminar 17401). In Dagstuhl Reports, Volume 7, Issue 10, pp. 1-13, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)

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@Article{mosca_et_al:DagRep.7.10.1,
  author =	{Mosca, Michele and Sendrier, Nicolas and Steinwandt, Rainer and Svore, Krysta},
  title =	{{Quantum Cryptanalysis (Dagstuhl Seminar 17401)}},
  pages =	{1--13},
  journal =	{Dagstuhl Reports},
  ISSN =	{2192-5283},
  year =	{2018},
  volume =	{7},
  number =	{10},
  editor =	{Mosca, Michele and Sendrier, Nicolas and Steinwandt, Rainer and Svore, Krysta},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagRep.7.10.1},
  URN =		{urn:nbn:de:0030-drops-86605},
  doi =		{10.4230/DagRep.7.10.1},
  annote =	{Keywords: computational algebra, post-quantum cryptography, quantum circuit complexity, quantum computing, quantum hardware and resource estimation}
}
Document
DOI: 10.4230/DagRep.5.9.1
Quantum Cryptanalysis (Dagstuhl Seminar 15371)

Authors: Michele Mosca, Martin Roetteler, Nicolas Sendrier, and Rainer Steinwandt

Published in: Dagstuhl Reports, Volume 5, Issue 9 (2016)

Abstract
This report documents the program and the outcomes of Dagstuhl Seminar 15371 "Quantum Cryptanalysis". In this seminar, participants explored the impact that quantum algorithms will have on cryptology once a large-scale quantum computer becomes available. Research highlights in this seminar included both computational resource requirement and availability estimates for meaningful quantum cryptanalytic attacks against conventional cryptography, as well as the security of proposed quantum-safe cryptosystems against emerging quantum cryptanalytic attacks.
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Michele Mosca, Martin Roetteler, Nicolas Sendrier, and Rainer Steinwandt. Quantum Cryptanalysis (Dagstuhl Seminar 15371). In Dagstuhl Reports, Volume 5, Issue 9, pp. 1-17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2016)

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@Article{mosca_et_al:DagRep.5.9.1,
  author =	{Mosca, Michele and Roetteler, Martin and Sendrier, Nicolas and Steinwandt, Rainer},
  title =	{{Quantum Cryptanalysis (Dagstuhl Seminar 15371)}},
  pages =	{1--17},
  journal =	{Dagstuhl Reports},
  ISSN =	{2192-5283},
  year =	{2016},
  volume =	{5},
  number =	{9},
  editor =	{Mosca, Michele and Roetteler, Martin and Sendrier, Nicolas and Steinwandt, Rainer},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagRep.5.9.1},
  URN =		{urn:nbn:de:0030-drops-56825},
  doi =		{10.4230/DagRep.5.9.1},
  annote =	{Keywords: Cryptography, Quantum computing, Post-quantum cryptography, Quantum algorithms, Cryptanalysis, Computational algebra, Quantum circuit complexity, Quantum hardware and resource estimation}
}
Document
DOI: 10.4230/DagRep.3.9.59
Quantum Cryptanalysis (Dagstuhl Seminar 13371)

Authors: Serge Fehr, Michele Mosca, Martin Rötteler, and Rainer Steinwandt

Published in: Dagstuhl Reports, Volume 3, Issue 9 (2014)

Abstract
This report documents the program and the outcomes of Dagstuhl Seminar 13371 "Quantum Cryptanalysis". In the first part, the motivation and organizational aspects of this meeting are outlined. Thereafter, abstracts for the presentations are provided (sorted alphabetically by last name of the presenter)
Cite as

Serge Fehr, Michele Mosca, Martin Rötteler, and Rainer Steinwandt. Quantum Cryptanalysis (Dagstuhl Seminar 13371). In Dagstuhl Reports, Volume 3, Issue 9, pp. 59-73, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2014)

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@Article{fehr_et_al:DagRep.3.9.59,
  author =	{Fehr, Serge and Mosca, Michele and R\"{o}tteler, Martin and Steinwandt, Rainer},
  title =	{{Quantum Cryptanalysis (Dagstuhl Seminar 13371)}},
  pages =	{59--73},
  journal =	{Dagstuhl Reports},
  ISSN =	{2192-5283},
  year =	{2014},
  volume =	{3},
  number =	{9},
  editor =	{Fehr, Serge and Mosca, Michele and R\"{o}tteler, Martin and Steinwandt, Rainer},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagRep.3.9.59},
  URN =		{urn:nbn:de:0030-drops-43575},
  doi =		{10.4230/DagRep.3.9.59},
  annote =	{Keywords: security of cryptographic schemes, quantum algorithms, computational hardness assumptions}
}
Document
DOI: 10.4230/DagRep.1.9.58
Quantum Cryptanalysis (Dagstuhl Seminar 11381)

Authors: Serge Fehr, Michele Mosca, Martin Rötteler, and Rainer Steinwandt

Published in: Dagstuhl Reports, Volume 1, Issue 9 (2012)

Abstract
This report documents the program and the outcomes of Dagstuhl Seminar 11381 ``Quantum Cryptanalysis''. The first section gives an overview of the meeting, including organizational aspects. Subsequently abstracts of presentations at the meeting are provided (in alphabetical order).
Cite as

Serge Fehr, Michele Mosca, Martin Rötteler, and Rainer Steinwandt. Quantum Cryptanalysis (Dagstuhl Seminar 11381). In Dagstuhl Reports, Volume 1, Issue 9, pp. 58-75, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2011)

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@Article{fehr_et_al:DagRep.1.9.58,
  author =	{Fehr, Serge and Mosca, Michele and R\"{o}tteler, Martin and Steinwandt, Rainer},
  title =	{{Quantum Cryptanalysis (Dagstuhl Seminar 11381)}},
  pages =	{58--75},
  journal =	{Dagstuhl Reports},
  ISSN =	{2192-5283},
  year =	{2011},
  volume =	{1},
  number =	{9},
  editor =	{Fehr, Serge and Mosca, Michele and R\"{o}tteler, Martin and Steinwandt, Rainer},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagRep.1.9.58},
  URN =		{urn:nbn:de:0030-drops-33675},
  doi =		{10.4230/DagRep.1.9.58},
  annote =	{Keywords: Security of cryptographic schemes, quantum algorithms, computational hardness assumptions}
}
Document
DOI: 10.4230/DagSemProc.08491.1
08491 Abstracts Collection – Theoretical Foundations of Practical Information Security

Authors: Ran Canetti, Shafi Goldwasser, Günter Müller, and Rainer Steinwandt

Published in: Dagstuhl Seminar Proceedings, Volume 8491, Theoretical Foundations of Practical Information Security (2009)

Abstract
From 30.11. to 05.12.2008, the Dagstuhl Seminar 08491 ``Theoretical Foundations of Practical Information Security '' was held in Schloss Dagstuhl~--~Leibniz Center for Informatics. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topics and goals in general. Links to extended abstracts or full papers are provided, if available.
Cite as

Ran Canetti, Shafi Goldwasser, Günter Müller, and Rainer Steinwandt. 08491 Abstracts Collection – Theoretical Foundations of Practical Information Security. In Theoretical Foundations of Practical Information Security. Dagstuhl Seminar Proceedings, Volume 8491, pp. 1-16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2009)

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@InProceedings{canetti_et_al:DagSemProc.08491.1,
  author =	{Canetti, Ran and Goldwasser, Shafi and M\"{u}ller, G\"{u}nter and Steinwandt, Rainer},
  title =	{{08491 Abstracts Collection – Theoretical Foundations of Practical Information Security}},
  booktitle =	{Theoretical Foundations of Practical Information Security},
  pages =	{1--16},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2009},
  volume =	{8491},
  editor =	{Ran Canetti and Shafi Goldwasser and G\"{u}nter M\"{u}ller and Rainer Steinwandt},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.08491.1},
  URN =		{urn:nbn:de:0030-drops-18945},
  doi =		{10.4230/DagSemProc.08491.1},
  annote =	{Keywords: Organic computing, self-organisation, design, adaptivity}
}
Document
DOI: 10.4230/DagSemProc.08491.2
08491 Executive Summary – Theoretical Foundations of Practical Information Security

Authors: Ran Canetti, Shafi Goldwasser, Günter Müller, and Rainer Steinwandt

Published in: Dagstuhl Seminar Proceedings, Volume 8491, Theoretical Foundations of Practical Information Security (2009)

Abstract
Designing, building, and operating secure information processing systems is a complex task, and the only scientific way to address the diverse challenges arising throughout the life-cycle of security criticial systems is to consolidate and increase the knowledge of the theoretical foundations of practical security problems. To this aim, the mutual exchange of ideas across individual security research communities can be extraordinary beneficial. Accordingly, the motivation of this Dagstuhl seminar was the integration of different research areas with the common goal of providing an integral theoretical basis that is needed for the design of secure information processing systems.
Cite as

Ran Canetti, Shafi Goldwasser, Günter Müller, and Rainer Steinwandt. 08491 Executive Summary – Theoretical Foundations of Practical Information Security. In Theoretical Foundations of Practical Information Security. Dagstuhl Seminar Proceedings, Volume 8491, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2009)

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@InProceedings{canetti_et_al:DagSemProc.08491.2,
  author =	{Canetti, Ran and Goldwasser, Shafi and M\"{u}ller, G\"{u}nter and Steinwandt, Rainer},
  title =	{{08491 Executive Summary – Theoretical Foundations of Practical Information Security }},
  booktitle =	{Theoretical Foundations of Practical Information Security},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2009},
  volume =	{8491},
  editor =	{Ran Canetti and Shafi Goldwasser and G\"{u}nter M\"{u}ller and Rainer Steinwandt},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.08491.2},
  URN =		{urn:nbn:de:0030-drops-18938},
  doi =		{10.4230/DagSemProc.08491.2},
  annote =	{Keywords: Organic computing, self-organisation, design, adaptivity}
}
Document
DOI: 10.4230/DagSemProc.08491.3
Modeling Computational Security in Long-Lived Systems

Authors: Ran Canetti, Ling Cheung, Dilsun Kaynar, Nancy Lynch, and Olivier Pereira

Published in: Dagstuhl Seminar Proceedings, Volume 8491, Theoretical Foundations of Practical Information Security (2009)

Abstract
For many cryptographic protocols, security relies on the assumption that adversarial entities have limited computational power. This type of security degrades progressively over the lifetime of a protocol. However, some cryptographic services, such as timestamping services or digital archives, are emph{long-lived} in nature; they are expected to be secure and operational for a very long time (ie super-polynomial). In such cases, security cannot be guaranteed in the traditional sense: a computationally secure protocol may become insecure if the attacker has a super-polynomial number of interactions with the protocol. This paper proposes a new paradigm for the analysis of long-lived security protocols. We allow entities to be active for a potentially unbounded amount of real time, provided they perform only a polynomial amount of work emph{per unit of real time}. Moreover, the space used by these entities is allocated dynamically and must be polynomially bounded. We propose a new notion of emph{long-term implementation}, which is an adaptation of computational indistinguishability to the long-lived setting. We show that long-term implementation is preserved under polynomial parallel composition and exponential sequential composition. We illustrate the use of this new paradigm by analyzing some security properties of the long-lived timestamping protocol of Haber and Kamat.
Cite as

Ran Canetti, Ling Cheung, Dilsun Kaynar, Nancy Lynch, and Olivier Pereira. Modeling Computational Security in Long-Lived Systems. In Theoretical Foundations of Practical Information Security. Dagstuhl Seminar Proceedings, Volume 8491, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2009)

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@InProceedings{canetti_et_al:DagSemProc.08491.3,
  author =	{Canetti, Ran and Cheung, Ling and Kaynar, Dilsun and Lynch, Nancy and Pereira, Olivier},
  title =	{{Modeling Computational Security in Long-Lived Systems}},
  booktitle =	{Theoretical Foundations of Practical Information Security},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2009},
  volume =	{8491},
  editor =	{Ran Canetti and Shafi Goldwasser and G\"{u}nter M\"{u}ller and Rainer Steinwandt},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.08491.3},
  URN =		{urn:nbn:de:0030-drops-18908},
  doi =		{10.4230/DagSemProc.08491.3},
  annote =	{Keywords: Long lived security; universally composable security;}
}
Document
DOI: 10.4230/DagSemProc.08491.4
Public-Key Cryptosystems from the Worst-Case Shortest Vector Problem

Authors: Chris Peikert

Published in: Dagstuhl Seminar Proceedings, Volume 8491, Theoretical Foundations of Practical Information Security (2009)

Abstract
We construct public-key cryptosystems that are secure assuming the *worst-case* hardness of approximating the shortest vector problem on lattices. Prior cryptosystems with worst-case connections (e.g., the Ajtai-Dwork system) were based either on a *special case* of the shortest vector problem, or on the conjectured hardness of lattice problems for *quantum* algorithms. Our main technical innovation is a reduction from certain variants of the shortest vector problem to corresponding versions of the "learning with errors" (LWE) problem; previously, only a quantum reduction of this kind was known. In addition, we construct new cryptosystems based on LWE, including a very natural chosen ciphertext-secure system that has a much simpler description and tighter underlying worst-case approximation factor than prior constructions. (Duration: 30 minutes, on or before Wednesday.)
Cite as

Chris Peikert. Public-Key Cryptosystems from the Worst-Case Shortest Vector Problem. In Theoretical Foundations of Practical Information Security. Dagstuhl Seminar Proceedings, Volume 8491, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2009)

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@InProceedings{peikert:DagSemProc.08491.4,
  author =	{Peikert, Chris},
  title =	{{Public-Key Cryptosystems from the Worst-Case Shortest Vector Problem}},
  booktitle =	{Theoretical Foundations of Practical Information Security},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2009},
  volume =	{8491},
  editor =	{Ran Canetti and Shafi Goldwasser and G\"{u}nter M\"{u}ller and Rainer Steinwandt},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.08491.4},
  URN =		{urn:nbn:de:0030-drops-18922},
  doi =		{10.4230/DagSemProc.08491.4},
  annote =	{Keywords: Lattice-based cryptography, learning with errors, quantum computation}
}
Document
DOI: 10.4230/DagSemProc.08491.5
Sound and Fine-grain Specification of Ideal Functionalities

Authors: Juan Garay, Aggelos Kiayias, and Hong-Sheng Zhou

Published in: Dagstuhl Seminar Proceedings, Volume 8491, Theoretical Foundations of Practical Information Security (2009)

Abstract
Nowadays it is widely accepted to formulate the security of a protocol carrying out a given task via the "trusted-party paradigm," where the protocol execution is compared with an ideal process where the outputs are computed by a trusted party that sees all the inputs. A protocol is said to securely carry out a given task if running the protocol with a realistic adversary amounts to "emulating" the ideal process with the appropriate trusted party. In the Universal Composability (UC) framework the program run by the trusted party is called an ideal functionality. While this simulation-based security formulation provides strong security guarantees, its usefulness is contingent on the properties and correct specification of the ideal functionality, which, as demonstrated in recent years by the coexistence of complex, multiple functionalities for the same task as well as by their "unstable" nature, does not seem to be an easy task. In this paper we address this problem, by introducing a general methodology for the sound specification of ideal functionalities. First, we introduce the class of canonical ideal functionalities for a cryptographic task, which unifies the syntactic specification of a large class of cryptographic tasks under the same basic template functionality. Furthermore, this representation enables the isolation of the individual properties of a cryptographic task as separate members of the corresponding class. By endowing the class of canonical functionalities with an algebraic structure we are able to combine basic functionalities to a single final canonical functionality for a given task. Effectively, this puts forth a bottom-up approach for the specification of ideal functionalities: first one defines a set of basic constituent functionalities for the task at hand, and then combines them into a single ideal functionality taking advantage of the algebraic structure. In our framework, the constituent functionalities of a task can be derived either directly or, following a translation strategy we introduce, from existing game-based definitions; such definitions have in many cases captured desired individual properties of cryptographic tasks, albeit in less adversarial settings than universal composition. Our translation methodology entails a sequence of steps that derive a corresponding canonical functionality given a game-based definition. In this way, we obtain a well-defined mapping of game-based security properties to their corresponding UC counterparts. Finally, we demonstrate the power of our approach by applying our methodology to a variety of basic cryptographic tasks, including commitments, digital signatures, zero-knowledge proofs, and oblivious transfer. While in some cases our derived canonical functionalities are equivalent to existing formulations, thus attesting to the validity of our approach, in others they differ, enabling us to "debug" previous definitions and pinpoint their shortcomings.
Cite as

Juan Garay, Aggelos Kiayias, and Hong-Sheng Zhou. Sound and Fine-grain Specification of Ideal Functionalities. In Theoretical Foundations of Practical Information Security. Dagstuhl Seminar Proceedings, Volume 8491, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2009)

Copy BibTex To Clipboard

@InProceedings{garay_et_al:DagSemProc.08491.5,
  author =	{Garay, Juan and Kiayias, Aggelos and Zhou, Hong-Sheng},
  title =	{{Sound and Fine-grain Specification of Ideal Functionalities}},
  booktitle =	{Theoretical Foundations of Practical Information Security},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2009},
  volume =	{8491},
  editor =	{Ran Canetti and Shafi Goldwasser and G\"{u}nter M\"{u}ller and Rainer Steinwandt},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.08491.5},
  URN =		{urn:nbn:de:0030-drops-18911},
  doi =		{10.4230/DagSemProc.08491.5},
  annote =	{Keywords: Security definitions, universal composability, cryptographic protocols, lattices and partial orders.}
}
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