IACR News
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28 March 2022
Lin You, Xinhua Zhang, Gengran Hu, Longbo Han
ePrint ReportSuparna Kundu, Jan-Pieter D’Anvers, Michiel Van Beirendonck, Angshuman Karmakar, Ingrid Verbauwhede
ePrint ReportZhonghui Ge, Yi Zhang, Yu Long, Dawu Gu
ePrint ReportIn this work, we introduce Shaduf, a novel non-cycle off-chain rebalancing protocol that offers a new solution for users to shift coins between channels directly without relying on the cycle setting. Shaduf can be applied to more general rebalancing scenarios. We provide the details of Shaduf and formally prove its security under the Universal Composability framework. Our prototype demonstrates its feasibility and the experimental evaluation shows that Shaduf enhances the Lighting Network performance in payment success ratio and volume. Experimental results also show that our protocol prominently reduces users’ deposits in channels while maintaining the same amount of payments. Moreover, as a privacy enhancement of Shaduf, we propose Shaduf++. Shaduf++ not only retains all the advantages of Shaduf, but also preserves privacy for the rebalancing operations.
Hridya P R, Jimmy Jose
ePrint ReportLin You, Yan Wang, Liang Li, Gengran Hu
ePrint ReportGuillaume Barbu, Ward Beullens, Emmanuelle Dottax, Christophe Giraud, Agathe Houzelot, Chaoyun Li, Mohammad Mahzoun, Adrián Ranea, Jianrui Xie
ePrint ReportErtem Nusret Tas, Dionysis Zindros, Lei Yang, David Tse
ePrint ReportMegan Chen, Alessandro Chiesa, Nicholas Spooner
ePrint ReportIn this paper we identify a natural oracle model, the low-degree random oracle model, in which there exist transparent SNARKs for all NP computations relative to this oracle. Informally, letting $\mathcal{O}$ be a low-degree encoding of a random oracle, and assuming the existence of (standard-model) collision-resistant hash functions, there exist SNARKs relative to $\mathcal{O}$ for all languages in $\mathsf{NP}^{\mathcal{O}}$. Such a SNARK can directly prove a computation about its own verifier. This capability leads to proof-carrying data (PCD) in the oracle model $\mathcal{O}$ based solely on the existence of (standard-model) collision-resistant hash functions.
To analyze this model, we introduce a more general framework, the linear code random oracle model (LCROM). We show how to obtain SNARKs in the LCROM for computations that query the oracle, given an accumulation scheme for oracle queries in the LCROM. Then we construct such an accumulation scheme for the special case of a low degree random oracle.
Matteo Campanelli, Rosario Gennaro, Kelsey Melissaris, Luca Nizzardo
ePrint ReportHirotomo Shinoki, Koji Nuida
ePrint ReportThe contributions of this paper are twofold. First, the syntax of KH-PKE supposes that homomorphic evaluation is performed for single operations, and its security notion called KH-CCA security was formulated based on this syntax. Consequently, if the homomorphic evaluation algorithm is enhanced in a way of gathering up sequential operations as a single evaluation, then it is not obvious whether or not KH-CCA security is preserved. In this paper, we show that KH-CCA security is in general not preserved under such modification, while KH-CCA security is preserved when the original scheme additionally satisfies circuit privacy.
Secondly, Catalano and Fiore (ACM CCS 2015) proposed a conversion method from linearly HE schemes into two-level HE schemes, the latter admitting addition and a single multiplication for ciphertexts. In this paper, we extend the conversion to the case of linearly KH-PKE schemes to obtain two-level KH-PKE schemes. Moreover, based on the generalized version of Catalano-Fiore conversion, we also construct a similar conversion from d-level KH-PKE schemes into 2d-level KH-PKE schemes.
Brett Hemenway Falk, Rohit Nema, Rafail Ostrovsky
ePrint ReportS. Dov Gordon, Carmit Hazay, Phi Hung Le
ePrint ReportAntoine Urban, Matthieu Rambaud
ePrint ReportTo achieve this goal, we design a new approach with short threshold fully homomorphic (FHE) ciphertexts, which in turn impacts the computational complexity. The main building block of our technique is a threshold encryption scheme which is Ad-Hoc, i.e., which only takes as parameter $N$ public keys independently generated, equipped with a threshold shrinking mechanism into threshold FHE ciphertexts.
One ingredient of independent interest is a linear secret sharing over RLWE rings with arbitrary modulus. By contrast, previous threshold FHE required the modulus to be prime and at least as large as $N+1$.
Another significant advantage of this approach is that it also allows an arbitrary number of lightweight {external input owners} to feed their inputs in the computation by simply encrypting them with the Ad-Hoc scheme, then go offline.
We finally prove the impossibility of $1$-Broadcast-then-Asynchronous MPC for $N\leq 3t-4$, showing tightness of our $2$ broadcasts.
Hamidreza Khoshakhlagh
ePrint Report27 March 2022
Gachon University, Korea
Job PostingClosing date for applications:
Contact: Professor Seong Oun Hwang (seongoun.hwang at gmail.com).
More information: https://ai-security.github.io/index_e.htm
FAU Erlangen-Nürnberg
Job Posting10 PhD positions (m/f/d) (salary level 13 TV-L) in Computer Science (full time) and Law (part time, 75%)
within the Research Training Group 2475 „Cybercrime and Forensic Computing“ funded by the German Research Foundation (DFG) commencing on October 1, 2022. The Research Training Group aims to systematically analyse research questions arising from the interaction between computer science and criminal law. The principal investigators of this project offer expertise in the following areas:
- Computer security, digital forensic science
- Criminal law, criminal procedure
- Criminology
- Theoretical computer science (logic, semantics, automata)
- Pattern recognition, image processing, image forensics
- Cryptography
- Hardware-software-co-design
More information about the project can be found at https://cybercrime.fau.de Applicants should have an excellent academic record, hold an MSc, LL.M. or an equivalent university degree in computer science, law or related disciplines, and have the goal to finish a PhD degree within three years.
Founded in 1743 and situated at the heart of the Nuremberg Metropolitan Region, FAU is a strong research university with an international perspective and one of the largest universities in Germany. FAU’s outstanding research and teaching is reflected in top positions in both national and international rankings, as well as the high amount of DFG funding which its researchers are able to secure. FAU aims to increase the number of women in scientific positions. Female candidates are therefore particularly encouraged to apply. In case of equal qualifications, candidates with disabilities will take precedence. Please submit your complete application documents by 18.4.2022 to cybercrime-applications@fau.de. Please mention in your application at least two research areas from the above list which you are specifically interested in. Interviews will commence between 7. and 10.6.2022 in Erlangen.
Closing date for applications:
Contact: Felix Freiling (felix.freiling@fau.de) regarding positions in computer science and Dominique Schröder (dominique.schroeder@fau.de) regarding cryptography.
More information: https://www.cybercrime.fau.de/stellen-open-positions/
24 March 2022
Hanoï, Viêt Nam, 24 August - 30 August 2022
School23 March 2022
TU Wien
Job PostingTasks:
- Deep interest in scientific problems and the motivation for independent and goal-oriented research
- Independent teaching or participation in teaching and supervision of students
- Ability to develop methods, concepts, as well as their realization and evaluation and the willingness to contribute in interdisciplinary scientific projects
- Participation in organizational and administrative tasks of the research unit and the faculty
- Completion of an appropriate doctorate and in-depth knowledge of the subject area
- An outstanding publication record in top security and privacy conferences
- Research background in one of the following topics: formal methods for security and privacy, blockchain technologies, intersection between machine learning and security or privacy, or web security
- Experience in teaching and publication activities as well as interest and pleasure in research and working with students
- Organisational and analytical skills as well as a structured way of working
- Excellent skills in English communication and writing
- Continuing personal and professional education and flexible working hours
- Central location of workplace with very good accessibility (U1/U4 Karlsplatz)
- A creative environment in one of the most liveable cities in the world
- (B1 scale, 56.861,70 EUR per year before tax)
- Additional benefits for employees
Closing date for applications:
Contact: Matteo Maffei
More information: https://jobs.tuwien.ac.at/Job/179063
The Netherlands
Job Posting- Lattice-based cryptography
- Privacy-preserving machine learning
- Privacy and applied cryptography
- Blockchain/smart contract security
- PhD in Computer Science, Information Security, Maths.
- Strongly related knowledge and backgrounds (e.g., research papers) of privacy-oriented cryptography (theory and/or practice).
- Professional in English (writing, speaking). Note Dutch is NOT required.
Closing date for applications:
Contact: Dr. S. Fu (shihui.fu@tudelft.nl)
SUTD, Singapore
Job PostingClosing date for applications:
Contact: Prof. Jianying Zhou. Email: jianying_zhou (at) sutd.edu.sg
More information: http://jianying.space/