IACR News
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14 January 2022
Vipul Goyal, Justin Raizes, Pratik Soni
ePrint ReportWe study zero-knowledge and secure computation through the lens of a new security notion where the simulator is given the ability to ``time-travel” or more accurately, to look into the future states of the blockchain and use this information to perform simulation. Such a time-traveling simulator gives a novel security guarantee of the following form: whatever the adversary could have learnt from an interaction, it could have computed on its own shortly into the future (e.g., a few hours from now).
We exhibit the power of time-traveling simulators by constructing round-efficient protocols in the blockchain-hybrid model. In particular, we construct: 1. Three-round zero-knowledge (ZK) argument for NP with a polynomial-time black-box time-traveling simulator. 2. Three-round secure two-party computation (2PC) for any functionality with a polynomial-time black-box time-traveling simulator for both parties.
In addition to standard cryptographic assumptions, we rely on natural hardness assumptions for Proof-of-Work based blockchains. In comparison, in the plain model, three-round protocols with black-box simulation are impossible, and constructions with non-black-box simulation for ZK require novel cryptographic assumptions while no construction for three-round 2PC is known. Our three-round 2PC result relies on a new, two-round extractable commitment that admits a time-traveling extractor.
Varun Madathil, Chris Orsini, Alessandra Scafuro, Daniele Venturi
ePrint ReportJonathan Godin, Philippe Lamontagne
ePrint ReportThe main thesis of this paper is that deletion-compliance is a standalone notion, distinct from privacy. We present an alternative definition that meaningfully captures deletion-compliance without any privacy implications. This allows broader class of data collectors to demonstrate compliance to deletion requests and to be paired with various notions of privacy. Our new definition has several appealing properties: - It is implied by the stronger definition of Garg et al. under natural conditions, and is equivalent when we add a privacy requirement. - It is naturally composable with minimal assumptions. - Its requirements are met by data structure implementations that do not reveal the order of operations, a concept known as history-independence.
Along the way, we discuss the many challenges that remain in providing a universal definition of compliance to the "right to be forgotten."
Denis Firsov, Sven Laur, Ekaterina Zhuchko
ePrint ReportPierre-Alain Fouque, Paul Kirchner, Thomas Pornin, Yang Yu
ePrint ReportJinyu Lu, Guoqiang Liu, Yunwen Liu, Bing Sun, Chao Li, Li Liu
ePrint ReportUniversity of Tübingen, Department of Computer Science; Tübingen, Germany
Job PostingResearch Topics: Development and analysis of cryptography-based privacy-preserving solutions for real-world healthcare problems. Topics of interest include (but are not limited to): privacy-preserving machine learning, genomic privacy, medical privacy as well as foundations for real-world cryptography.
Your profile:
- Completed Master's degree (or equivalent) at a top university with excellent grades in computer science, or a similar area.
- Extensive knowledge in applied cryptography/security and machine learning.
- Very good software development skills.
- Knowledge of cryptographic protocols (ideally MPC).
- Knowledge of bioinformatics or genomics is plus.
- Self-motivated, reliable, creative, can work independently and want to do excellent research.
Closing date for applications:
Contact: Dr. Mete Akgün (mete.akguen@uni-tuebingen.de)
University of Innsbruck, Austria, EU
Job PostingThe University of Innsbruck, located in the heart of the alps, has a tenure track opportunity in the field of cryptography.
The Department of Computer Science is looking for an ambitious researcher to build a bridge between the interdisciplinary approach taken by its Security & Privacy Lab and theoretical research groups, like Computational Logic and Theoretical Computer Science. Research activities would focus on producing evidence on the security or privacy of cryptographic systems covering theory and/or implementation. The individual should be comfortable teaching multiple approaches to cryptography. The ideal candidate would build a research group on cryptography in the course of the tenure process, the details of which are negotiated in the first year of employment as routinely done in the Austrian academic system.
Tyrol, Austria is one of the most livable places in Europe with world-class healthcare, excellent social security, and free education from kindergarden to university.
Applications are due on 28 January 2022. Follow the link above for more details.
Closing date for applications:
Contact: Rainer Böhme [rainer dot boehme at uibk.ac.at]
More information: https://informationsecurity.uibk.ac.at/pdfs/vacancy_cryptography_2022.pdf
10 January 2022
Graz University of Technology, Graz, Austria
Job PostingIn order to complement our team, we are looking for a full-time PhD researcher in the implementation aspects of cryptography.
Responsibilities:
The PhD researcher will be working on Scientific research in the field of implementation and physical security aspects of novel cryptographic algorithms within the “Cyroptografic Engineering” group within the “Secure Systems” area at IAIK.
Required Qualifications:
How to apply: Applications, curriculum vitae and other documents should preferably be uploaded here csbme.tugraz.at/go/applications/7050-21-013.
The earliest starting date for the PhD candidate will be March 2022.
The application deadline is February 6th.
Closing date for applications:
Contact: Sujoy Sinha-Roy - sujoy.sinha-roy@iaik.tugraz.at
More information: https://www.tugraz.at/tu-graz/karriere/ausgeschriebene-jobs/ausgeschriebene-wissenschaftliche-stellen-ausser-professuren/#c427935
ADVA Optical Networking, Munich, Germany
Job PostingClosing date for applications:
Contact: Joo Yeon Cho (jcho@adva.com)
More information: https://adva.wd3.myworkdayjobs.com/en-US/ADVA/job/Munich-Germany/Engineer-Advanced-Technology--M-F-D-_R001000
Laboratoire Hubert Curien, University of Lyon, Saint-Etienne, France
Job PostingClosing date for applications:
Contact: Contact: Prof. Lilian BOSSUET lilian.bossuet(at)univ-st-etienne.fr
CryptoExperts, Paris, France
Job PostingCryptoExperts develops and maintains a white-box cryptography technology which aims at producing white-box cryptography software components secure against beyond-state-of-the-art attacks.
We are looking for a candidate who will take part to the design and implementation effort of CryptoExperts’ white-box cryptography technology.
The complete job offer is available here: https://www.cryptoexperts.com/job-offer-wbc.pdf
Closing date for applications:
Contact: To apply please write to jobs@cryptoexperts.com with a short description of your profile, story and motivation, your CV, and (optionally) recommendation from (former) co-workers.
More information: https://www.cryptoexperts.com/job-offer-wbc.pdf
Norwegian University of Sciennce and Technology (NTNU), Dep. of Inf. Security and Comm. Technology
Job PostingRequired qualifications: You must have the qualifications required for the position of associate professor in the field of Cyptology, as outlined:
A. Your PhD, or comparable academic work, must be within the field of cryptology (or a comparable relevant field), of particular interest are candidates with a documented acadmic track record within one or several of the following topics: A1. Design and analysis of post-quantum cryptographic primitives; A2. Design and analysis of post-quantum cryptographic protocols; A3. Lightweight cryptography; A4. Blockchain technologies; A5. Cryptography and Privacy; A6. Homomorphic encryption; A7. Secure Cryptographic Hardware, Side Channels Security (attacks and resistance); A8. Cryptology and Biometrics; A9. Cryptology and Software Security (Secure Operating Systems).
B. Relevant academic fields include mathematics, computer science and communication technology. If you can document that you are in the final stages of your PhD studies, your application may also be considered.
C. Good written and oral English language skills.
More information about the position and the whole application process should be completed via the initial Jobbnorge link and web page
Closing date for applications:
Contact: Professor Danilo Gligoroski, e-mail danilo.gligoroski@ntnu.no
More information: https://www.jobbnorge.no/en/available-jobs/job/216381/associate-professor-in-cryptology
Amit Choudhari, Sylvain Guilley, Khaled Karray
ePrint ReportWe performed a feature-wise comparison with the existing state of the art solutions. CRYScanner includes additional features, preserving the capabilities of both static and dynamic analysis tools. We also show the detection of potential vulnerabilities in the several sample codes found online.
Elette Boyle, Itai Dinur, Niv Gilboa, Yuval Ishai , Nathan Keller, Ohad Klein
ePrint ReportNear-optimal LPHS via Distributed Discrete Log: We establish a general two-way connection between LPHS and algorithms for distributed discrete logarithm in the generic group model. Using such an algorithm of Dinur et al. (Crypto 2018), we get LPHS with near-optimal error of $\delta=\tilde O(1/d^2)$. This gives an unusual example for the usefulness of group-based cryptography in a post-quantum world. We extend the positive result to non-cyclic and worst-case variants of LPHS.
Multidimensional LPHS: We obtain positive and negative results for a multidimensional extension of LPHS, making progress towards an optimal 2-dimensional LPHS.
Applications: We demonstrate the usefulness of LPHS by presenting cryptographic and algorithmic applications. In particular, we apply multidimensional LPHS to obtain an efficient "packed" implementation of homomorphic secret sharing and a sublinear-time implementation of location-sensitive encryption whose decryption requires a significantly overlapping view.
Bingyong Guo, Yuan Lu, Zhenliang Lu, Qiang Tang, Jing Xu, Zhenfeng Zhang
ePrint ReportDespite those efforts, asynchronous BFT protocols remain to be slow, and in particular, the latency is still quite large. There are two reasons contributing to the inferior performance: (1) the reliable broadcast (RBC) protocols still incur substantial costs; (2) the MVBA protocols are quite complicated and heavy, and all existing constructions need dozens of rounds and take the majority of he overall latency.
We first present a new construction of asynchronous BFT that replaces RBC instance with a cheaper broadcast component. It not only reduces the $O(n^3)$ message complexity incurred by $n$ RBCs to $O(n^2)$, but also saves up to 67% communications (in the presence of a fair network scheduler). Moreover, our technical core is a new MVBA protocol, Speeding MVBA, which is concretely more efficient than all existing MVBAs. It requires only 6 rounds in the best case and expected 12 rounds in the worst case (by contrast, several dozens of rounds in the MVBA from Cachin et al. [12] and the recent Dumbo-MVBA [32], and around 20 rounds in the MVBA from Abraham et al. [4]). Our new technique of the construction might be of independent interests.
We implemented Speeding Dumbo and did extensive tests among up to 150 EC2 t2.medium instances evenly allocated in 15 AWS regions across the globe. The experimental results show that Speeding Dumbo reduces the latency to about a half of Dumbo's, and also doubles the throughput of Dumbo, through all system scales from 4 nodes to 150 nodes. We also did tests to benchmark individual components such as the broadcasts and the MVBA protocols, which may be of interests for future improvements.
Andrada-Teodora Ciulei, Marian-Codrin Crețu, Emil Simion
ePrint ReportMostafizar Rahman, Dhiman Saha, Goutam Paul
ePrint Report08 January 2022
Jean-Philippe Bossuat, Juan Ramón Troncoso-Pastoriza, Jean-Pierre Hubaux
ePrint ReportWe present a bootstrapping procedure for the CKKS scheme that combines both dense and sparse secrets. Our construction enables the use of parameters for which the homomorphic capacity is based on a dense secret, yet with a bootstrapping complexity that remains the one of a sparse secret and with a large security margin. Moreover, this also enables us to easily parameterize the bootstrapping circuit so that it has a negligible failure probability that, to the best of our knowledge, has never been achieved for the CKKS scheme. When using the parameters of previous works, our bootstrapping procedures enables a faster procedure with an increased precision and lower failure probability. For example we are able to bootstrapp a plaintext of $\mathbb{C}^{32768}$ in 20.2 sec, with 32.11 bits of precision, 285 bits of modulus remaining, a failure probability of $2^{-138.7}$ and 128 bit security.