4 Search Results for "Dujmovic, Jesko"

Document
DOI: 10.4230/LIPIcs.ITCS.2026.62
Improved Rate for Non-Malleable Codes and Time-Lock Puzzles

Authors: Cody Freitag, Ilan Komargodski, Manu Kondapaneni, and Jad Silbak

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

Abstract
Non-malleable codes allow a sender to transmit a message to a receiver, while providing a "best-possible" integrity guarantee to ensure that no attacker - who cannot already decode the message - can meaningfully tamper the message in transit. If tampered, the received message should either be invalid or unrelated to the original message. Non-malleable time-lock puzzles (TLPs) are a special case of non-malleable codes for bounded polynomial-depth tampering with very efficient encoding. In this work, we give generic techniques for constructing non-malleable codes and non-malleable TLPs with improved rate, which captures the ratio of a message’s length to its encoding length. A key contribution of our work is identifying a security notion for non-malleability, which we term "CCA-hiding", sufficient for our compilers. CCA-hiding is a relaxation of CCA-security for encryption or commitments to the fine-grained setting of codes, and requires that the encoded message remains hidden, even given a decoding oracle for any other codeword. Intriguingly, CCA-hiding does not imply non-malleability in the fine-grained setting, as is the case for encryption and commitments. Using our new techniques, we give the following constructions: - Rate-1 CCA-hiding TLPs in the plain model. - Rate-1 non-malleable codes for bounded polynomial-depth tampering in the auxiliary-input random oracle model (AI-ROM). - Rate-(1/2) non-malleable TLPs in the AI-ROM.
Cite as

Cody Freitag, Ilan Komargodski, Manu Kondapaneni, and Jad Silbak. Improved Rate for Non-Malleable Codes and Time-Lock Puzzles. In 17th Innovations in Theoretical Computer Science Conference (ITCS 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 362, pp. 62:1-62:24, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

Copy BibTex To Clipboard

@InProceedings{freitag_et_al:LIPIcs.ITCS.2026.62,
  author =	{Freitag, Cody and Komargodski, Ilan and Kondapaneni, Manu and Silbak, Jad},
  title =	{{Improved Rate for Non-Malleable Codes and Time-Lock Puzzles}},
  booktitle =	{17th Innovations in Theoretical Computer Science Conference (ITCS 2026)},
  pages =	{62:1--62:24},
  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.2026.62},
  URN =		{urn:nbn:de:0030-drops-253490},
  doi =		{10.4230/LIPIcs.ITCS.2026.62},
  annote =	{Keywords: Non-malleable codes, Time-lock puzzles}
}
Document
DOI: 10.4230/LIPIcs.ITCS.2025.56
Incompressible Functional Encryption

Authors: Rishab Goyal, Venkata Koppula, Mahesh Sreekumar Rajasree, and Aman Verma

Published in: LIPIcs, Volume 325, 16th Innovations in Theoretical Computer Science Conference (ITCS 2025)

Abstract
Incompressible encryption (Dziembowski, Crypto'06; Guan, Wichs, Zhandry, Eurocrypt'22) protects from attackers that learn the entire decryption key, but cannot store the full ciphertext. In incompressible encryption, the attacker must try to compress a ciphertext within pre-specified memory bound S before receiving the secret key. In this work, we generalize the notion of incompressibility to functional encryption. In incompressible functional encryption, the adversary can corrupt non-distinguishing keys at any point, but receives the distinguishing keys only after compressing the ciphertext to within S bits. An important efficiency measure for incompressible encryption is the ciphertext-rate (i.e., rate = |m|/|ct|). We give many new results for incompressible functional encryption for circuits, from minimal assumption of (non-incompressible) functional encryption, with 1) ct-rate-1/2 and short secret keys, 2) ct-rate-1 and large secret keys. Along the way, we also give a new incompressible attribute-based encryption for circuits from standard assumptions, with ct-rate-1/2 and short secret keys. Our results achieve optimal efficiency, as incompressible attribute-based/functional encryption with ct-rate-1 as well as short secret keys has strong barriers for provable security from standard assumptions. Moreover, our assumptions are minimal as incompressible attribute-based/functional encryption are strictly stronger than their non-incompressible counterparts.
Cite as

Rishab Goyal, Venkata Koppula, Mahesh Sreekumar Rajasree, and Aman Verma. Incompressible Functional Encryption. In 16th Innovations in Theoretical Computer Science Conference (ITCS 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 325, pp. 56:1-56:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

Copy BibTex To Clipboard

@InProceedings{goyal_et_al:LIPIcs.ITCS.2025.56,
  author =	{Goyal, Rishab and Koppula, Venkata and Rajasree, Mahesh Sreekumar and Verma, Aman},
  title =	{{Incompressible Functional Encryption}},
  booktitle =	{16th Innovations in Theoretical Computer Science Conference (ITCS 2025)},
  pages =	{56:1--56:22},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-361-4},
  ISSN =	{1868-8969},
  year =	{2025},
  volume =	{325},
  editor =	{Meka, Raghu},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ITCS.2025.56},
  URN =		{urn:nbn:de:0030-drops-226849},
  doi =		{10.4230/LIPIcs.ITCS.2025.56},
  annote =	{Keywords: functional encryption, attribute-based encryption, incompressible encryption}
}
Document
DOI: 10.4230/LIPIcs.ITC.2022.4
Maliciously Circuit-Private FHE from Information-Theoretic Principles

Authors: Nico Döttling and Jesko Dujmovic

Published in: LIPIcs, Volume 230, 3rd Conference on Information-Theoretic Cryptography (ITC 2022)

Abstract
Fully homomorphic encryption (FHE) allows arbitrary computations on encrypted data. The standard security requirement, IND-CPA security, ensures that the encrypted data remain private. However, it does not guarantee privacy for the computation performed on the encrypted data. Statistical circuit privacy offers a strong privacy guarantee for the computation process, namely that a homomorphically evaluated ciphertext does not leak any information on how the result of the computation was obtained. Malicious statistical circuit privacy requires this to hold even for maliciously generated keys and ciphertexts. Ostrovsky, Paskin and Paskin (CRYPTO 2014) constructed an FHE scheme achieving malicious statistical circuit privacy. Their construction, however, makes non-black-box use of a specific underlying FHE scheme, resulting in a circuit-private scheme with inherently high overhead. This work presents a conceptually different construction of maliciously circuit-private FHE from simple information-theoretical principles. Furthermore, our construction only makes black-box use of the underlying FHE scheme, opening the possibility of achieving practically efficient schemes. Finally, in contrast to the OPP scheme in our scheme, pre- and post-homomorphic ciphertexts are syntactically the same, enabling new applications in multi-hop settings.
Cite as

Nico Döttling and Jesko Dujmovic. Maliciously Circuit-Private FHE from Information-Theoretic Principles. In 3rd Conference on Information-Theoretic Cryptography (ITC 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 230, pp. 4:1-4:21, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)

Copy BibTex To Clipboard

@InProceedings{dottling_et_al:LIPIcs.ITC.2022.4,
  author =	{D\"{o}ttling, Nico and Dujmovic, Jesko},
  title =	{{Maliciously Circuit-Private FHE from Information-Theoretic Principles}},
  booktitle =	{3rd Conference on Information-Theoretic Cryptography (ITC 2022)},
  pages =	{4:1--4:21},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-238-9},
  ISSN =	{1868-8969},
  year =	{2022},
  volume =	{230},
  editor =	{Dachman-Soled, Dana},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ITC.2022.4},
  URN =		{urn:nbn:de:0030-drops-164826},
  doi =		{10.4230/LIPIcs.ITC.2022.4},
  annote =	{Keywords: Fully Homomorphic Encryption, FHE, Homomorphic Encryption, Oblivious Transfer, Malicious Statistical Circuit Privacy, Multi-Hop, Information Theory, Cryptography}
}
Document
DOI: 10.4230/LIPIcs.ITCS.2022.2
Algebraic Restriction Codes and Their Applications

Authors: Divesh Aggarwal, Nico Döttling, Jesko Dujmovic, Mohammad Hajiabadi, Giulio Malavolta, and Maciej Obremski

Published in: LIPIcs, Volume 215, 13th Innovations in Theoretical Computer Science Conference (ITCS 2022)

Abstract
Consider the following problem: You have a device that is supposed to compute a linear combination of its inputs, which are taken from some finite field. However, the device may be faulty and compute arbitrary functions of its inputs. Is it possible to encode the inputs in such a way that only linear functions can be evaluated over the encodings? I.e., learning an arbitrary function of the encodings will not reveal more information about the inputs than a linear combination. In this work, we introduce the notion of algebraic restriction codes (AR codes), which constrain adversaries who might compute any function to computing a linear function. Our main result is an information-theoretic construction AR codes that restrict any class of function with a bounded number of output bits to linear functions. Our construction relies on a seed which is not provided to the adversary. While interesting and natural on its own, we show an application of this notion in cryptography. In particular, we show that AR codes lead to the first construction of rate-1 oblivious transfer with statistical sender security from the Decisional Diffie-Hellman assumption, and the first-ever construction that makes black-box use of cryptography. Previously, such protocols were known only from the LWE assumption, using non-black-box cryptographic techniques. We expect our new notion of AR codes to find further applications, e.g., in the context of non-malleability, in the future.
Cite as

Divesh Aggarwal, Nico Döttling, Jesko Dujmovic, Mohammad Hajiabadi, Giulio Malavolta, and Maciej Obremski. Algebraic Restriction Codes and Their Applications. In 13th Innovations in Theoretical Computer Science Conference (ITCS 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 215, pp. 2:1-2:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)

Copy BibTex To Clipboard

@InProceedings{aggarwal_et_al:LIPIcs.ITCS.2022.2,
  author =	{Aggarwal, Divesh and D\"{o}ttling, Nico and Dujmovic, Jesko and Hajiabadi, Mohammad and Malavolta, Giulio and Obremski, Maciej},
  title =	{{Algebraic Restriction Codes and Their Applications}},
  booktitle =	{13th Innovations in Theoretical Computer Science Conference (ITCS 2022)},
  pages =	{2:1--2:15},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-217-4},
  ISSN =	{1868-8969},
  year =	{2022},
  volume =	{215},
  editor =	{Braverman, Mark},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ITCS.2022.2},
  URN =		{urn:nbn:de:0030-drops-155987},
  doi =		{10.4230/LIPIcs.ITCS.2022.2},
  annote =	{Keywords: Algebraic Restriction Codes, Oblivious Transfer, Rate 1, Statistically Sender Private, OT, Diffie-Hellman, DDH}
}
  • Refine by Type
  • 4 Document/PDF
  • 2 Document/HTML

  • Refine by Publication Year
  • 1 2026
  • 1 2025
  • 2 2022

  • Refine by Author
  • 2 Dujmovic, Jesko
  • 2 Döttling, Nico
  • 1 Aggarwal, Divesh
  • 1 Freitag, Cody
  • 1 Goyal, Rishab
  • Show More...

  • Refine by Series/Journal
  • 4 LIPIcs

  • Refine by Classification
  • 2 Security and privacy → Information-theoretic techniques
  • 2 Security and privacy → Public key encryption
  • 1 Security and privacy → Public key (asymmetric) techniques
  • 1 Theory of computation → Computational complexity and cryptography

  • Refine by Keyword
  • 2 Oblivious Transfer
  • 1 Algebraic Restriction Codes
  • 1 Cryptography
  • 1 DDH
  • 1 Diffie-Hellman
  • Show More...

Any Issues?
X

Feedback on the Current Page

CAPTCHA

Thanks for your feedback!

Feedback submitted to Dagstuhl Publishing

Could not send message

Please try again later or send an E-mail
© 2023-2026 Schloss Dagstuhl – LZI GmbH Schloss Dagstuhl – LZI GmbH About DROPS Imprint Privacy Contact