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15 October 2021
Vidal Attias, Luigi Vigneri, Vassil Dimitrov
ePrint ReportChaya Ganesh, Claudio Orlandi, Mahak Pancholi, Akira Takahashi, Daniel Tschudi
ePrint ReportPrior to this work, there was no evidence that malleability attacks were not possible against Fiat-Shamir Bulletproofs. Malleability attacks can lead to very severe vulnerabilities, as they allow an adversary to forge proofs re-using or modifying parts of the proofs provided by the honest parties. In this paper, we show for the first time that Bulletproofs (or any other similar multi-round proof system satisfying some form of weak unique response property) achieve simulation-extractability in the algebraic group model.
This implies that Fiat-Shamir Bulletproofs are non-malleable.
Chandan Dey, Sumit Kumar Pandey, Tapabrata Roy, Santanu Sarkar
ePrint ReportLéo Ducas, Wessel van Woerden
ePrint ReportKeyu Ji, Bingsheng Zhang, Tianpei Lu, Lichun Li, Kui Ren
ePrint ReportWai-Kong Lee, Hwajeong Seo, Seong Oun Hwang, Angshuman Karmakar, Jose Maria Bermudo Mera, Ramachandra Achar
ePrint ReportTarun Yadav, Manoj Kumar
ePrint ReportLilya Budaghyan, Ivana Ivkovic, Nikolay Kaleyski
ePrint ReportMichaella Pettit
ePrint ReportNabil Alkeilani Alkadri, Patrick Harasser, Christian Janson
ePrint ReportOlivier Bernard, Tuong-Huy Nguyen, Andrea Lesavourey, Adeline Roux-Langlois
ePrint ReportIn this paper, our main contribution is to extend these experiments to 192 cyclotomic fields of any conductor $m$ and of degree up to $190$. Building upon new results from Bernard and Kucera on the Stickelberger ideal, we construct a maximal set of independent $\mathcal{S}$-units lifted from the maximal real subfield using explicit Stickelberger generators obtained via Jacobi sums. Hence, we obtain full-rank log-$\mathcal{S}$-unit sublattices fulfilling the role of approximating the full Tw-PHS lattice. Notably, our obtained approximation factors match those from Bernard and Roux-Langlois using the original log-$\mathcal{S}$-unit lattice in small dimensions.
As a side result, we use the knowledge of these explicit Stickelberger elements to remove almost all quantum steps in the CDW algorithm, by Cramer, Ducas and Wesolowski in 2021, under the mild restriction that the plus part of the class number verifies $h^{+}_{m}\leq O(\sqrt{m})$.
Jung Hee Cheon, Dongwoo Kim, Keewoo Lee
ePrint ReportXavier Salleras, Vanesa Daza
ePrint ReportMiguel Ambrona, Romain Gay
ePrint ReportWe provide the first MA-ABE scheme from prime-order pairings where no trusted setup is needed and where the attribute universe of each authority is unbounded. Our constructions rely on a common modular blueprint that uses an Identity-Based Functional Encryption scheme for inner products (ID-IPFE) as an underlying primitive. Our presentation leads to simple proofs of security and brings new insight into the algebraic design choices that seem common to existing schemes. In particular, the well-known MA-ABE construction by Lewko and Waters (EUROCRYPT 2011) can be seen as a specific instantiation of our modular construction.
Our schemes enjoy all of their advantageous features, and the improvements mentioned. Furthermore, different instantiations of the core ID-IPFE primitive lead to various security/efficiency trade-offs: we propose an adaptively secure construction proven in the generic group model and a selectively secure one that relies on SXDH. As in previous work, we rely on a hash function (to generate matching randomness for the same user across different authorities while preserving collusion resistance) that is modeled as a random oracle.
Nirvan Tyagi, Julia Len, Ian Miers, Thomas Ristenpart
ePrint ReportMatthias Fitzi, Aggelos Kiayias, Giorgos Panagiotakos, Alexander Russell
ePrint ReportIn this work we put forth Ofelimos, a novel PoUW-based block\-chain protocol whose consensus mechanism simultaneously realizes a decentralized optimization-problem solver. Our protocol is built around a novel local search algorithm, which we call Doubly Parallel Local Search (DPLS), that is especially crafted to suit implementation as the PoUW component of our blockchain protocol. We provide a thorough security analysis of our protocol and additionally present metrics that reflect the usefulness of the system. As an illustrative example we show how DPLS can implement a variant of WalkSAT and experimentally demonstrate its competitiveness with respect to a vanilla WalkSAT implementation. In this way, our work paves the way for safely using blockchain systems as generic optimization engines for a variety of hard optimization problems for which a publicly verifiable solution is desired.
Tim Beyne, Siemen Dhooghe, Amir Moradi, Aein Rezaei Shahmirzadi
ePrint Report14 October 2021
Max Planck Institute for Security and Privacy, Bochum, Germany
Job PostingTopic: Lattice-based Vector Commitments
Requirements:
- Have working knowledge in constructing and analysing public-key cryptographic primitives
- Are familiar with mathematical proofs
- Are fluent in spoken and written English
- Have basic understanding of lattice-based cryptography
- Have basic understanding of vector commitments
- Have experience in prototyping cryptographic primitives
Start Date: As soon as possible
Duration: 3 to 6 months
Application Deadline: December 31, 2021, or when a suitable candidate has been found
To apply for the position, send an email to Giulio Malavolta (address below) including the following documents:
- A curriculum vitae
- A brief cover letter (half page at most), e.g. describing your research interests
Closing date for applications:
Contact: Giulio Malavolta (giulio.malavolta@mpi-sp.org)
ENS Lyon
Job PostingThe ENS Lyon crypto group is opening several post-doc positions. Duration and starting dates are flexible. Salary takes seniority into account.
Topics of interest:Applicants should have expertise in at least one of the following topics:
- Cryptographic protocols
- Lattice-based cryptography
- Lattice algorithms or hardness of lattice problems (quantum/classical)
- Foundational aspects of cryptography
- Computing on encrypted data
- Implementation of cryptographic primitives
How to apply:
Interested applicants should provide a detailed resume and two references. Applications should be sent directly to {benoit.libert,alain.passelegue, damien.stehle}@ens-lyon.fr by Dec. 31, 2021.
Closing date for applications:
Contact: Benoît Libert, Alain Passelègue, and Damien Stehlé
{benoit.libert,
alain.passelegue, damien.stehle}@ens-lyon.fr
More information: https://www.ens-lyon.fr/LIP/AriC/crypto
Heliax, Anoma
Job PostingClosing date for applications:
Contact: jobs@heliax.dev
More information: https://heliax.dev/