IACR News
Here you can see all recent updates to the IACR webpage. These updates are also available:
10 April 2024
Décio Luiz Gazzoni Filho, Tomás S. R. Silva, Julio López
Stanislav Peceny, Srinivasan Raghuraman, Peter Rindal, Harshal Shah
We give two novel protocols for efficiently generating a random permutation correlation. The first makes use of recent advances in MPC-friendly PRFs to obtain a protocol requiring $O(n\ell)$ OTs/time and constant rounds to permute $n$ $\ell$-bit strings. Unlike the modern OT extension techniques we rely on, this was previously only achievable from relatively more expensive public-key cryptography, e.g. Paillier or LWE. We implement this protocol and demonstrate that it can generate a correlation for $n=2^{20},\ell=128$ in 19 seconds and $\sim2\ell n$ communication, a 15 \& $1.1\times$ improvement over the LWE solution of Juvekar at al. (CCS 2018). The second protocol is based on pseudo-random correlation generators and achieves an overhead that is \emph{sublinear} in the string length $\ell$, i.e. the communication and number of OTs is $O(n\log \ell)$. The latter protocol is ideal for the setting when you need to repeatedly permute secret-shared data by the same permutation, e.g. in graph algorithms.
Finally, we present a suite of highly efficient protocols for performing various batched random access operations. These include a class of protocols we refer to as \emph{extraction}, which allow a user to \emph{mark} a subset of $X$ and have this subset obliviously extracted into an output list. Additionally, the parties can specify an \emph{arbitrary} selection function $\sigma:[n]\rightarrow[n]$ and obtain shares of $\sigma(X)=(X_{\sigma(1)},\ldots,X_{\sigma(n)})$ from $X$. We implement these protocols and report on their performance.
Martin R. Albrecht, Matilda Backendal, Daniele Coppola, Kenneth G. Paterson
We provide the first detailed documentation and security analysis of Nextcloud's E2EE feature. Nextcloud's strong security claims motivate conducting the analysis in the setting where the server itself is considered malicious. We present three distinct attacks against the E2EE security guarantees in this setting. Each one enables the confidentiality and integrity of all user files to be compromised. All three attacks are fully practical and we have built proof-of-concept implementations for each. The vulnerabilities make it trivial for a malicious Nextcloud server to access and manipulate users' data.
We have responsibly disclosed the three vulnerabilities to Nextcloud. The second and third vulnerabilities have been remediated. The first was addressed by temporarily disabling file sharing from the E2EE feature until a redesign of the feature can be made. We reflect on broader lessons that can be learned for designers of E2EE systems.
09 April 2024
Paris, France, 26 June 2024
Submission deadline: 5 May 2024
Notification: 12 May 2024
Arlington, USA, 23 October - 25 October 2024
Submission deadline: 6 June 2024
Notification: 30 July 2024
Halifax, Canada, 4 September 2024
Brandenburg University of Technology, Chair of IT Security
- Privacy-Enhancing Technologies in Cyber-Physical Systems.
- AI-based Network Attack Detection and Simulation.
- AI-enabled Penetration Testing.
Closing date for applications:
Contact: Ivan Pryvalov (ivan.pryvalov@b-tu.de)
Graz University of Technology
Join our Cryptographic Engineering research team at the Technical University of Graz (TU Graz) in Austria! We are seeking a one PhD and one postdoctoral researchers.
You will contribute to an exciting research project advancing isogeny-based cryptography. This role offers a unique opportunity to collaborate with leading experts in the field and perform cutting-edge research.
The Cryptographic Engineering research team is based at IAIK, TU Graz, the largest university institute in Austria for research and education in security and privacy. It has been active in this field for more than 30 years and currently employs more than 60 researchers.
Required Qualifications for PhD position:The ideal candidate for the PhD position will hold a master's degree with project experience in the implementation aspects (e.g., efficient implementation, side-channel analysis, fault analysis, etc.) of cryptography, preferably in isogeny-based cryptography.
Required Qualifications for Postdoc position:The ideal candidate for the postdoc position will hold a PhD (or be close to completion) in cryptography and be an expert in isogeny-based cryptography and/or secure implementation aspects of cryptography.
How to apply:
Submit your applications, CV, and other documents before 1st May, 2024.
https://jobs.tugraz.at/en/jobs/bbba0417-7a9c-69a5-f012-6613bd4b383f/apply?preview=true
Closing date for applications: The application deadline is May 1st, 2024.
Closing date for applications:
Contact: Sujoy Sinha Roy – sujoy.sinharoy@iaik.tugraz.at
Vu Amsterdam
Closing date for applications:
Contact: Kristina Sojakova
More information: https://workingat.vu.nl/vacancies/phd-in-effective-and-scalable-tools-against-side-channel-attacks-amsterdam-1064918
Quantstamp
Quantstamp is looking for an applied cryptographer. Quantstamp often deals with a wide range of cryptographic problems, including reviewing implementations and tackling new theoretical problems using cryptography. For example, Quantstamp regularly receives requests to review code bases which either invoke or implement (custom) cryptography, as part of an audit.
Requirments
Closing date for applications:
Contact: candidate-upload-to-job-N7wnRj36Krf2zX@inbox.ashbyhq.com
More information: https://jobs.ashbyhq.com/quantstamp/6ae4fc70-98bb-42e1-9f24-c40e7af441cc
Monash University; Melbourne, Australia
- highly competitive scholarships to cover tuition fees, health insurance and living expenses (as stipend),
- opportunities to collaborate with leading academic and industry experts in the related areas,
- opportunities to participate in international grant-funded projects,
- collaborative and friendly research environment,
- an opportunity to live/study in one of the most liveable and safest cities in the world.
Requirements. A strong mathematical and cryptography background is required. Some knowledge/experience in coding (for example, Python, C/C++, SageMath) is a plus. Candidates must have completed (or be about to complete within the next 8 months) a significant research component either as part of their undergraduate (honours) degree or masters degree. They should have excellent English verbal and written communication skills.
How to apply. please first refer to mfesgin.github.io/supervision/ for more information. Then, please fill out the following form (also clickable from the advertisement title): https://docs.google.com/forms/d/e/1FAIpQLScOvp0w397TQMTjTa6T7TKqri703Z-c3en0aS654w6nl4_EFg/viewform
Closing date for applications:
Contact: Muhammed Esgin
More information: https://docs.google.com/forms/d/e/1FAIpQLScOvp0w397TQMTjTa6T7TKqri703Z-c3en0aS654w6nl4_EFg/viewform
08 April 2024
Vincent Gramoli, Zhenliang Lu, Qiang Tang, Pouriya Zarbafian
In this paper, we introduce a protocol for state machine replication with fair separability ($\mathsf{SMRFS}$); moreover, our protocol has communication complexity $\mathcal{O}(n\ell+\lambda n^2)$, where $n$ is the number of processes, $\ell$ is the input (transaction) size, and $\lambda$ is the security parameter. This is optimal when $\ell\geq \lambda n$, while previous works have cubic communication. To the best of our knowledge, $\mathsf{SMRFS}$ is the first protocol to achieve fair separability, and the first implementation of fair ordering that has optimal communication complexity and optimal Byzantine resilience.
Novak Kaluderovic, Nan Cheng, Katerina Mitrokotsa
Prabhanjan Ananth, Aditya Gulati, Yao-Ting Lin
Our main result is the construction of a statistically secure PRSG with: (a) the output length of the PRSG is strictly larger than the key size, (b) the security holds even if the adversary receives $O\left(\frac{\lambda}{(\log(\lambda))^{1.01}} \right)$ copies of the pseudorandom state. We show the optimality of our construction by showing a matching lower bound. Our construction is simple and its analysis uses elementary techniques.
Jun Xu, Zhiwei Li, Lei Hu
Loïc Bidoux, Thibauld Feneuil, Philippe Gaborit, Romaric Neveu, Matthieu Rivain
While a straightforward application of these frameworks already improve the existing MPCitH-based signatures, we show in this work that we can adapt the arithmetic constraints representing the underlying security assumptions (here called the modeling) to achieve smaller sizes using these new techniques. More precisely, we explore existing modelings for the rank syndrome decoding (RSD) and MinRank problems and we introduce a new modeling, named dual support decomposition, which achieves better sizes with the VOLEitH and TCitH frameworks by minimizing the size of the witnesses. While this modeling is naturally more efficient than the other ones for a large set of parameters, we show that it is possible to go even further and explore new areas of parameters. With these new modeling and parameters, we obtain low-size witnesses which drastically reduces the size of the ``arithmetic part'' of the signature. We apply our new modeling to both TCitH and VOLEitH frameworks and compare our results to RYDE, MiRitH, and MIRA signature schemes. We obtain signature sizes below 4 kB for 128 bits of security with N=256 parties (a.k.a. leaves in the GGM trees) and going as low as $\approx$ 3.5 kB with N=2048, for both RSD and MinRank. This represents an improvement of more than 1.5 kB compared to the original submissions to the 2023 NIST call for additional signatures. We also note that recent techniques optimizing the sizes of GGM trees are applicable to our schemes and further reduce the signature sizes by a few hundred bytes, bringing them arround 3 kB (for 128 bits of security with N=2048).
Russell W. F. Lai, Giulio Malavolta
In this work we put forward a new sequentiality assumption, which essentially says that a repeated application of the standard lattice-based hash function cannot be parallelised. We provide concrete evidence of the validity of this assumption and perform some initial cryptanalysis. We also propose a new template to construct proofs of sequential work, based on lattice techniques.
Daniel Larsson
Let us, already in the abstract, preface this note by remarking that we have not done any explicit computer experiments and benchmarks (apart from a small test on the speed of computing the orbits), nor do we make any security claims. Part of the reason for this is the author's lack of competence in complexity theory and evaluation of security claims. Instead this note is only meant as a presentation of the main idea, the hope being that someone more competent will find it interesting enough to pursue further.