IACR News
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11 July 2023
Kwan Yin Chan, Handong Cui, Tsz Hon Yuen
In this paper, we propose an optimized solution for TLS 1.3 websites. We tackle a number of open problems, including the support of X25519 key exchange in TLS 1.3, the design of round-optimal three-party key exchange, the architecture of two-party computation of TLS 1.3 key scheduling, and circuit design optimized for two-party computation. We test our implementation with real world website and show that our optimization is necessary to avoid timeout in TLS handshake.
Trevor Yap, Shivam Bhasin, Stjepan Picek
Minki Hhan, Takashi Yamakawa, Aaram Yun
We establish a generic model of quantum computation for group-theoretic problems, which we call the quantum generic group model, as a quantum analog of its classical counterpart. Shor's algorithm for the discrete logarithm problem and related algorithms can be described in this model. We show the quantum complexity lower bounds and (almost) matching algorithms of the discrete logarithm and related problems in this model. More precisely, we prove the following results for a cyclic group $\mathcal G$ of prime order.
(1) Any generic quantum discrete logarithm algorithm must make $\Omega(\log |\mathcal G|)$ depth of group operation queries. This shows that Shor's algorithm that makes $O(\log |\mathcal G|)$ group operations is asymptotically optimal among the generic quantum algorithms, even considering parallel algorithms. (2) We observe that some (known) variations of Shor's algorithm can take advantage of classical computations to reduce the number and depth of quantum group operations. We introduce a model for generic hybrid quantum-classical algorithm that captures these variants, and show that these algorithms are almost optimal in this model. Any generic hybrid quantum-classical algorithm for the discrete logarithm problem with a total number of (classical or quantum) group operations $Q$ must make $\Omega(\log |\mathcal G|/\log Q)$ quantum group operations of depth $\Omega(\log\log |\mathcal G| - \log\log Q)$. In particular, if $Q={\rm poly}\log |\mathcal G|$, classical group operations can only save the number of quantum queries by a factor of $O(\log\log |\mathcal G|)$ and the quantum depth remains as $\Omega(\log\log |\mathcal G|)$. (3) When the quantum memory can only store $t$ group elements and use quantum random access memory (qRAM) of $r$ group elements, any generic hybrid quantum-classical algorithm must make either $\Omega(\sqrt{|\mathcal G|})$ group operation queries in total or $\Omega(\log |\mathcal G|/\log (tr))$ quantum group operation queries. In particular, classical queries cannot reduce the number of quantum queries beyond $\Omega(\log |\mathcal G|/\log (tr))$.
As a side contribution, we show a multiple discrete logarithm problem admits a better algorithm than solving each instance one by one, refuting a strong form of the quantum annoying property suggested in the context of password-authenticated key exchange protocol.
Alexander Bienstock, Paul Rösler, Yi Tang
To support the design of secure mesh messengers, we provide a new, more complete security model for mesh messaging. Our model captures forward and post-compromise security, as well as forward and post-compromise anonymity, both of which are especially important in this setting. We also identify novel, stronger confidentiality goals that can be achieved due to the special characteristics of mesh networks (e.g., delayed communication, distributed network and adversary).
Finally, we develop a new protocol, called ASMesh, that provably satisfies these security goals. For this, we revisit Signal's Double Ratchet and propose non-trivial enhancements. On top of that, we add a mechanism that provides forward and post-compromise anonymity. Thus, our protocol efficiently provides strong confidentiality and anonymity under past and future user corruptions. Most of our results are also applicable to traditional messaging.
We prove security of our protocols and evaluate their performance in simulated mesh networks. Finally, we develop a proof of concept implementation.
10 July 2023
University of Calgary, Department of Computer Science, Calgary, Canada
Applications are invited from qualified candidates for a 2-year postdoctoral fellowship appointment (extendable for one more year) in cryptography. Expertise in cryptography and strong mathematics background are essential, and knowledge of quantum information and computation are important advantages. The focus of the positions is on quantum-resistant cryptography and its application to securing communication in two-party and group settings.
A Ph.D. degree and evidence of excellence in research are required. Successful applicants are expected to maintain an active program of research, and participate in research activities with academic and industry partners in the grant. The annual salary is $55,000 - $65,000 (CAD) depending on the qualifications and experience. The positions are available immediately.
Applicants should include a cover letter describing their interest in the position, a curriculum vitae, a short research statement and at least two contacts for reference letters. Interested individuals should send their application to espri@ucalgary.ca
Inquiries may be addressed to Rei Safavi-Naini, (rei@ucalgary.ca). Applications will be considered as they are submitted until the position is filled.
About the University of Calgary & Calgary
The University of Calgary is Canada’s leading next-generation university. The university has reached its Eyes High goal to be recognized as one of Canada’s top five research universities. The University of Calgary recognizes that a diverse staff/faculty benefits and enriches the work, learning and research experiences of the entire campus and greater community.
Calgary has been named one of the world's most livable cities for years. Calgary is less than an hour’s drive from the Rocky Mountains and boasts the most extensive urban pathway and bikeway network in North America.
Closing date for applications:
Contact: Rei Safavi-Naini
Zürich, Schweiz, 25 May - 26 May 2024
Submission deadline: 4 September 2023
Notification: 15 September 2023
Bitget, department of Bitkeep,Remote
Closing date for applications:
Contact: mia
06 July 2023
University of Leiden, LIACS, The Netherlands
Closing date for applications:
Contact: Eleftheria Makri: e.makri@liacs.leidenuniv.nl
More information: https://www.universiteitleiden.nl/en/vacancies/2023/q3eng/23-48013889phd-candidate-privacy-preserving-machine-learning
Ruhr University Bochum, Germany and Technology Innovation Institute, Abu Dhabi
This position is a collaboration between Ruhr University Bochum (RUB) in Germany and the Technology Innovation Institute (TII) in Abu Dhabi. You will work closely with renowned experts Dr. Andre Esser from TII and Prof. Alexander May from RUB. The primary office is based at RUB, with generous travel opportunities and a planned multiple months research stay at the partnering TII.
The ideal candidate:
- Master's degree (obtained before the starting date) in mathematics, computer science, or a related field
- Strong knowledge of cryptology, particularly in code-based cryptography / cryptanalysis
- Excellent track record of completed classes in cryptography, cryptanalysis, coding theory, etc.
- Curiosity-driven, self-motivated and open to international exchange
- Proficient in spoken/written English as well as in any programming language
- Prior publications or contributed to research projects
To apply, please send the following documents via email:
- Cover letter expressing your interest in the position and summarizing your qualifications (1-2 pages)
- CV highlighting your educational background, research experience, and publications (if any)
- Copies of bachelor’s and master’s certificates
- Contact information for two or more academic references
Closing date for applications:
Contact: Andre Esser (andre.esser@tii.ae)
University of Trento, Department of Mathematics; Italy
Closing date for applications:
Contact: Marco Calderini
TU Darmstadt
Your profile:
- Completed PhD degree (or equivalent) at a top university in IT security, computer science, mathematics, electrical engineering, or a similar area.
- Publications at top venues for cryptography/IT Security (e.g., EUROCRYPT, CRYPTO, ASIACRYPT, S&P, CCS, TCC),
- Good knowledge in one of the topics mentioned above is a plus.
- Experience in project management and supervising students is a plus.
TU Darmstadt is a top research university for IT Security, Cryptography, and Computer Science in Europe. We offer an excellent working environment in the heart of the Frankfurt Metropolitan Area, which is internationally well-known for its high quality of life. The review of applications starts immediately until the position is filled.
Closing date for applications:
Contact: Sebastian Faust
TU Darmstadt
Your profile:
- Completed Master's degree (or equivalent) with excellent grades in computer science, mathematics, or a similar area.
- Strong mathematical and/or algorithmic/theoretical CS background
- Good knowledge in one of the topics mentioned above is a plus.
- Fluent in English
TU Darmstadt is a top research university for IT Security, Cryptography, and Computer Science in Europe. We offer an excellent working environment in the heart of the Frankfurt Metropolitan Area, which is internationally well-known for its high quality of life. The review of applications starts immediately until the position is filled.
Closing date for applications:
Contact: Sebastian Faust
University of St.Gallen, Switzerland
Our research interests are centered around information security and applied cryptography, with the larger goal of safeguarding communications and providing strong privacy guarantees. We are active in several areas, a subset of which include:
- Verifiable computation
- Secure, private and distributed aggregation
- Secure multi-party computation
- Privacy-preserving biometric authentication
- Anonymous credentials
- Distributed and privacy-preserving authentication
The starting date for the position is flexible and come with a very competitive salary. The selection process runs until the suitable candidate has been found. The University of St.Gallen conducts excellent research with international implications. The city of St.Gallen is located one hour from Zurich and offers a high quality of life.
Please apply by 20th July 2023 through the job portal (via link).
Closing date for applications:
Contact: Prof. Katerina Mitrokotsa - applications through job portal only.
More information: https://jobs.unisg.ch/offene-stellen/postdoc-fellow-in-cryptography-information-security-m-f-d/25ddb9d0-5c47-41ac-8bde-5789dbaca5c4
University of St.Gallen, Switzerland
The student is expected to work on topics that include security and privacy issues in authentication. More precisely, the student will be working on investigating efficient and privacy-preserving authentication that provides: i) provable security guarantees, and ii) rigorous privacy guarantees.
Key Responsibilities:
- Perform exciting and challenging research in the domain of information security and cryptography.
- Support and assist in teaching computer security and cryptography courses.
- The PhD student is expected to have a MSc degree or equivalent, and strong background in cryptography, network security and mathematics.
- Experience in one or more domains such as cryptography, design of protocols, secure multi-party computation and differential privacy is beneficial.
- Excellent programming skills.
- Excellent written and verbal communication skills in English
The starting date for the position is flexible and come with a very competitive salary. The selection process runs until the suitable candidate has been found.
Please apply by 20th July 2023 through the job portal (via link).
Closing date for applications:
Contact: Prof. Katerina Mitrokotsa - applications through job portal only.
More information: https://jobs.unisg.ch/offene-stellen/funded-phd-student-in-applied-cryptography-privacy-preserving-authentication-m-f-d/e7a9e90b-02cd-45d0-ad4f-fc02131eaf86
05 July 2023
Muhammad Imran
Fatemeh Heidari Soureshjani, Mathias Hall-Andersen, MohammadMahdi Jahanara, Jeffrey Kam, Jan Gorzny, Mohsen Ahmadvand
Zvika Brakerski, Maya Farber Brodsky, Yael Tauman Kalai, Alex Lombardi, Omer Paneth
This is the first $\mathsf{SNARG}$ under standard hardness assumptions for a sub-class of $\mathsf{NP}$ that is not known to have a (computational) non-signaling $\mathsf{PCP}$ with small locality. Indeed, our approach necessarily departs from the known framework of constructing $\mathsf{SNARG}$s dating back to [Kalai-Raz-Rothblum, STOC '13]
Our construction combines existing quasi-arguments for $\mathsf{NP}$ (based on batch arguments for $\mathsf{NP}$) with a novel ingredient which we call a predicate-extractable hash ($\mathsf{PEH}$) family. This notion generalizes the notion of a somewhere extractable hash. Whereas a somewhere extractable hash allows to extract a single input coordinate, our $\mathsf{PEH}$ extracts a global property of the input. We view this primitive to be of independent interest, and believe that it will find other applications.
Andrej Bogdanov, Pravesh Kothari, Alon Rosen
We explore the use of the low-degree method in the context of cryptography. To this end, we apply it in the design and analysis of a new public-key encryption scheme whose security is based on Goldreich's pseudorandom generator. The scheme is a combination of two proposals of Applebaum, Barak, and Wigderson, and inherits desirable features from both.