IACR News
Here you can see all recent updates to the IACR webpage. These updates are also available:
05 January 2024
Décio Luiz Gazzoni Filho, Guilherme Brandão, Julio López
Vasyl Ustimenko
Yuval Ishai, Eyal Kushnir, Ron D. Rothblum
Our notion relates the ability to accomplish some task when given a ciphertext, to accomplishing the same task without the ciphertext, in the context of communication complexity. Thus, we say that a scheme is combinatorially homomorphic if there exists a communication complexity problem $f(x,y)$ (where $x$ is Alice's input and $y$ is Bob's input) which requires communication $c$, but can be solved with communication less than $c$ when Alice is given in addition also an encryption $E_k(y)$ of Bob's input (using Bob's key $k$).
We show that this definition indeed captures pre-existing notions of homomorphic encryption and (suitable variants are) sufficiently strong to derive prior known implications of homomorphic encryption in a conceptually appealing way. These include constructions of (lossy) public-key encryption from homomorphic private-key encryption, as well as collision-resistant hash functions and private information retrieval schemes.
02 January 2024
Dubrovnik, Croatia, 9 September - 13 September 2024
Worcester, USA, 5 April 2024
Submission deadline: 2 February 2024
Notification: 5 March 2024
Vienna, Austria, 30 July - 2 August 2024
Submission deadline: 28 February 2024
Notification: 3 May 2024
1 July 2024
Submission deadline: 1 July 2024
UCSC---CSE Assistant Professor, Security and Privacy (initial review Jan. 5, 2024)
Closing date for applications:
Contact: Ioannis Demertzis or Alvaro Cardenas
More information: https://recruit.ucsc.edu/JPF01635
AIT Austrian Institute of Technology; Vienna, Austria
The cryptography team is conducting research in the domain of public key cryptography, including secure communication, privacy-enhancing technologies, and long-term and post-quantum security. Our research covers the full spectrum from idea creation to the development of prototypes and demonstrators.
The team is seeking to grow, and is therefore looking for a PhD-student in the fields of privacy and security in distributed systems.
Through our AIT-PhD programme with 150 internationals students, conducted in collaboration with renowned universities, applicants will have the opportunity to conduct their PhD thesis in collaboration with our experts and our national and international project partners from industry or other research institutions.
Requirements:
- Applicants are required to hold a MSc degree (or equivalent) in computer science, mathematics, or a related field
- Basic knowledge of cryptography (at least one course specializing on cryptography) is expected
- Special interest in applied research and the solution of practical problems, in particular in the areas of cryptography and information security
- High level of commitment and ability to work in a team
- Good knowledge of a programming language (e.g., C/C++, Rust, Java, Python) and software development is a plus
- Very good written and oral English skills; knowledge of German is not a requirement
The minimum gross annual salary on a full-time basis (38,5 h / week) according to the collective agreement is EUR 53.578,--. The actual salary will be determined individually, based on your qualifications and experience. In addition, we offer company benefits, flexible working conditions, individual training and career opportunities.
All applications (including cover letter and full CV) need to be submitted using the following link: https://jobs.ait.ac.at/Job/224352
Closing date for applications:
Contact: Stephan Krenn (stephan.krenn[at]ait.ac.at)
More information: https://jobs.ait.ac.at/Job/224352
Shanghai Jiao Tong University
Applicants should have (a) a doctoral degree in Computer Science, Electronic Engineering, Communication, Mathematics or Statistics; (b) an established track record in research and scholarship; (c) expertise in the cryptographic and security research areas; and (d) a demonstrated commitment to excellence in teaching.
The school will provide highly competitive remuneration packages and assist applicants to apply for various national, provincial and ministerial level talent programs such as “Outstanding Youth Talents Program”, Shanghai “Talents Program”,etc. We will also assist on employment of spouses, schooling for children and medical care.
Closing date for applications:
Contact:
Chaoping Xing, emial: xingcp@sjtu.edu.cn; Ni Liang, email: liangni@sjtu.edu.cn
Luxembourg Institute of Science and Technology
How will you contribute? Your specific mission includes, but is not limited to, participating into the following activities along with the project partners:
- To design and develop privacy-preserving federated data management technologies
- To prototype privacy-preserving technologies for cyberthreat intelligence, data analysis or cybersecurity
- To develop open-source software
- To validate the effectiveness of developed technologies You are in charge of disseminating and promoting the research activities that will be carried out, whether through publications, prototype development or technical reports
- Hold a PhD. degree in Computer Science or related disciplines
- Have good programming skills (particularly experience on Python and C++)
- Have good track record on applied cryptography, such as secure multiparty computation and homomorphic encryption. Knowledge on secure aggregation techniques or zero-knowledge proofs is a plus.
- Demonstrate strong interest and experience in anonymization techniques such as differential privacy, Google’s RAPPOR
Closing date for applications:
Contact: Orhan Ermis
More information: https://app.skeeled.com/offer/6554879c69ccf56b0c1432df?utm_id=60fed4c509c80d16d1bbe536&utm_medium=OFFERS_PORTAL&language=en&show_description=true
University of Surrey, UK
Fixed Term Contract until 30th September 2025
Closing Date: Monday 15th January
This post will work on challenges around decentralized identity and personal data, and approaches across distributed platforms such as Distributed Ledgers.
The Computer Science Research Centre at the University of Surrey is seeking to recruit a full-time researcher to the Surrey Centre for Cyber Security (SCCS). The successful candidate will join the DECaDE Next Stage Digital Economy Centre for the Decentralised Digital Economy (http://decade.ac.uk), a multidisciplinary UKRI-funded Centre with the University of Surrey, the University of Edinburgh, and the Digital Catapult.
The Centre is initially focused on three themes: value co-creation in the digital economy, data trusts for identity and data, and the world of work and the gig economy.
Surrey is recognized by the National Cyber Security Centre as an Academic Centre of Excellence in Cyber Security Research, and offers a thriving research environment with world leading researchers. We were also recognised as Cyber University of the Year 2023 in the National Cyber Awards. Our research includes security and privacy, verification, cryptography, distributed systems, and networked systems.
The position offers the platform for the research fellow to develop skills to become an independent researcher and to contribute to the DECaDE vision. The successful candidate will work within a team under the direction of Professor Steve Schneider. Significant interaction with project partners is encouraged, and the dissemination strategy may involve national and international travel, with many personal development opportunities.
Closing date for applications:
Contact: Contact: Professor Steve Schneider: s.schneider@surrey.ac.uk
More information: https://jobs.surrey.ac.uk/Vacancy.aspx?id=13775
31 December 2023
Riddhi Ghosal, Yuval Ishai, Alexis Korb, Eyal Kushilevitz, Paul Lou, Amit Sahai
We give the first evidence for the existence of unstructured hard languages in $\mathsf{NP} \,\cap\,\mathsf{coNP}$ by showing that if $\mathsf{UP} \not \subseteq \mathsf{RP}$, which follows from the existence of injective one-way functions, the answer to Bennett and Gill's question is affirmative: with probability 1 over a random oracle $\cal O$, we have that $\mathsf{P}^{\cal O} \neq \mathsf{NP}^{\cal O} \cap \mathsf{coNP}^{\cal O}$. Our proof gives a constructive non-black-box approach for obtaining candidate hard languages in $\mathsf{NP} \,\cap\,\mathsf{coNP}$ from cryptographic hash functions.
The above conditional separation builds on a new construction of non-interactive zero-knowledge (NIZK) proofs, with a computationally unbounded prover, to convert a hard promise problem into a hard language. We obtain such NIZK proofs for $\mathsf{NP}$, with a uniformly random reference string, from a special kind of hash function which is implied by (an unstructured) random oracle. This should be contrasted with previous constructions of such NIZK proofs that are based on one-way permutations or other structured primitives, as well as with (computationally sound) NIZK arguments in the random oracle model.
Zhengjun Cao, Zhenfu Cao
Anupam Chattopadhyay, Subhamoy Maitra, Bimal Mandal, Manmatha Roy, Deng Tang
Xinle Cao, Yuhan Li, Dmytro Bogatov, Jian Liu, Kui Ren
We present two oblivious FD protocols and prove them secure in the presence of the persistent adversary (monitoring processes on the server). The first protocol leverages Oblivious RAM (ORAM) and is suitable for dynamic databases. The second protocol relies on oblivious sorting and is more practical in static databases due to high parallelism. We also present a thorough experimental evaluation of the proposed methods.
Kelsey A. Jackson, Carl A. Miller, Daochen Wang
Shafik Nassar, Brent Waters, David J. Wu
In this work, we describe a generic approach for constructing monotone policy BARGs from any BARG for $\mathsf{NP}$ together with an additively homomorphic encryption scheme. This yields the first constructions of monotone policy BARGs from the $k$-Lin assumption in prime-order pairing groups as well as the (subexponential) DDH assumption in pairing-free groups. Central to our construction is a notion of a zero-fixing hash function, which is a relaxed version of a predicate-extractable hash function from the work of Brakerski et al. Our relaxation enables a direct realization of zero-fixing hash functions from standard BARGs for $\mathsf{NP}$ and additively homomorphic encryption, whereas the previous notion relied on leveled homomorphic encryption, and by extension, the LWE assumption.
Matteo Campanelli, Chaya Ganesh, Rosario Gennaro
Rational arguments are an interesting primitive because they allow for sublinear verification and a more efficient protocol in general. In this paper we aim at narrowing the gap between literature on rational schemes and real world applications. Our contribution is two-fold.
We provide the first construction of rational arguments for the class of polynomial computations that is practical (i.e., it can be applied to real-world computations on reasonably common hardware) and with logarithmic communication. Techniques-wise, we obtain this result through a compiler from information-theoretic protocols and rational proofs for polynomial evaluation. The latter could be of independent interest.
As a second contribution, we propose a new notion of extractability for rational arguments. Through this notion we can obtain arguments where knowledge of a witness is incentivized (rather than incentivizing mere soundness). We show how our aforementioned compiler can also be applied to obtain efficient extractable rational arguments for $\mathsf{NP}$.
Shuai Han, Shengli Liu, Dawu Gu
Firstly, we formalize the strong leakage and tamper-resilient (sLTR) security model for signature, which provides strong existential unforgeability, and deals with bounded leakage and restricted tampering attacks, as a counterpart to the sLTR security introduced by Sun et al. (ACNS 2019) for PKE.
Then, we present direct constructions of signature and chosen-ciphertext attack (CCA) secure PKE schemes in the sLTR model, based on the matrix decisional Diffie-Hellman (MDDH) assumptions (which covers the standard symmetric external DH (SXDH) and k-Linear assumptions) over asymmetric pairing groups. Our schemes avoid the use of heavy building blocks such as the true-simulation extractable non-interactive zero-knowledge proofs (tSE-NIZK) proposed by Dodis et al. (ASIACRYPT 2010), which are usually needed in constructing schemes with leakage and tamper-resilience. Especially, our SXDH-based signature and PKE schemes are more efficient than the existing schemes in the leakage and tamper-resilient setting: our signature scheme has only 4 group elements in the signature, which is about 5×~8× shorter, and our PKE scheme has only 6 group elements in the ciphertext, which is about 1.3×~3.3× shorter.
Finally, we note that our signature scheme is the {\it first} one achieving strong existential unforgeability in the leakage and tamper-resilient setting, where strong existential unforgeability has important applications in building more complex primitives such as signcryption and authenticated key exchange.