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29 March 2022
University of Bern, Switzerland
A Ph.D. position is available in the Cryptology and Data Security research group at the Institute of Computer Science, University of Bern, led by Christian Cachin.
https://crypto.unibe.ch/
Our research addresses all aspects of security in distributed systems, especially cryptographic protocols, consistency, consensus, and cloud-computing security. We are particularly interested in blockchains, distributed ledger technology, cryptocurrencies, and their security and economics.
Candidates should have a strong background in computer science. They should like conceptual, rigorous thinking for working theoretically, or be interested in building innovative systems for working practically. Demonstrated expertise in cryptography, distributed computing, or blockchain technology is a plus. Applicants must hold a master degree in the relevant research fields.
Positions are available starting immediately and come with a competitive salary. The selection process runs until suitable candidates have been found. The University of Bern conducts excellent research and lives up its vision that “Knowledge generates value”. The city of Bern lies in the center of Switzerland and offers some of the highest quality of life worldwide.
If you are interested, please apply be sending email with one single PDF file and subject line set to Application for Ph.D., addressed directly to Prof. Christian Cachin at crypto (at) inf.unibe.ch.
Since we receive many applications, we encourage you to include material that demonstrates your interests and strengths and sets you apart from others.
Closing date for applications:
Contact: Christian Cachin (https://crypto.unibe.ch/cc/)
More information: https://crypto.unibe.ch/jobs/
Cryspen
You will start out maintaining and extending the Cryspen HACL packages, a portable crypto library in C with Rust, OCaml, and JavaScript bindings, which is built on top of the HACL* verified cryptography from Inria and Microsoft Research. Later you will be primarily implementing new cryptographic primitives and protocols in Rust, ranging from secure multi party computation to post quantum cryptography.
Writing and maintaining cryptography is a delicate task that requires attention to detail and the utmost care; Cryspen's formally verified cryptography even more so. As an ideal candidate you are therefore able to handle highly sensitive and highly detailed tasks.
If you have experience with open source projects, that’s great but not necessary.
We expect that you understand the basics of all involved technologies and concepts. However, we especially invite you to apply if you are an early career professional or a recent graduate.
Closing date for applications:
Contact: job-application@cryspen.com
More information: https://docs.google.com/document/d/1WWplyJxIBXEEEyUZp5TFzuRYE5Vmn308NUIwe65oerE
University of St. Gallen, Switzerland
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.
Closing date for applications:
Contact: Prof. Katerina Mitrokotsa
University of St. Gallen, Switzerland
- Development and implementation of concepts and research results, both individually and in collaboration with researchers and PhD students,
- Run of experiments and simulation of realistic conditions to test the performance of developed algorithms and protocols,
- Development, maintenance and organization of software
- The successful applicant is expected to hold or to be about to receive a M.Sc. degree in Computer Science, Electrical Engineering, Applied Mathematics or similar fields, preferably with a focus in Security and Privacy for Computer Science Systems.
- We are looking for a strongly motivated and self-driven person who is able to work and learn new things independently.
- Good command of English is required.
- You should have a good academic track record and well developed analytical and problem solving skills.
- Excellent programming skills and familiarity with cryptographic libraries.
- Previous experience in implementation projects with C++, Matlab/Simulink, Python is desired.
Closing date for applications:
Contact: Prof. Katerina Mitrokotsa
More information: https://jobs.unisg.ch/offene-stellen/cryptography-engineer-m-w-d/4b359260-67ae-42af-a931-4cb7d9bcce9d
28 March 2022
Cas Cremers, Caroline Fontaine, Charlie Jacomme
Yael Tauman Kalai, Alex Lombardi, Vinod Vaikuntanathan, Lisa Yang
In conjunction with the rich literature on (entangled) multi-prover non-local games starting from the celebrated CHSH game (Clauser, Horne, Shimonyi and Holt, Physical Review Letters 1969), our compiler gives a broad framework for constructing mechanisms to classically verify quantum advantage.
Fukang Liu, Santanu Sarkar, Willi Meier, Takanori Isobe
Christopher Cordi, Michael P. Frank, Kasimir Gabert, Carollan Helinski, Ryan C. Kao, Vladimir Kolesnikov, Abrahim Ladha, Nicholas Pattengale
Daniel Gardham, Mark Manulis
An important yet challenging property for privacy-preserving ABS is revocation, which may be applied to signers or some of the attributes they possess. Existing ABS schemes lack efficient revocation of either signers or their attributes, relying on generic costly proofs.Moreover, in HABS there is a further need to support revocation of authorities on the delegation paths, which is not provided by existing HABS constructions.
This paper proposes a direct HABS scheme with a Verifier-Local Revocation (VLR) property. We extend the original HABS security model to address revocation and develop a new attribute delegation technique with appropriate VLR mechanism for HABS, which also implies the first ABS scheme to support VLR. Moreover, our scheme supports inner-product signing policies, offering a wider class of attribute relations than previous HABS schemes, and is the first to be based on lattices, which are thought to offer post-quantum security.
Fanliang Hu, Huanyu Wang, Junnian Wang
Likang Lu , Jianzhu Lu
Kimia Zamiri Azar, Muhammad Monir Hossain, Arash Vafaei, Hasan Al Shaikh, Nurun N. Mondol, Fahim Rahman, Mark Tehranipoor, Farimah Farahmandi
Yashvanth Kondi, abhi shelat
Pass (CRYPTO '03) first showed how to achieve this property for NP using a cut-and-choose technique which incurred a $\lambda^2$-bit overhead in communication where $\lambda$ is a security parameter. Fischlin (CRYPTO '05) presented a more efficient technique based on ``proofs of work'' that sheds this $\lambda^2$ cost, but only applies to a limited class of Sigma Protocols with a ``quasi-unique response'' property, which for example, does not necessarily include the standard OR composition for Sigma protocols.
With Schnorr/EdDSA signature aggregation as a motivating application, we develop new techniques to improve the computation cost of straight-line extractable proofs. Our improvements to the state of the art range from 70X--200X for the best compression parameters. This is due to a uniquely suited polynomial evaluation algorithm, and the insight that a proof-of-work that relies on multicollisions and the birthday paradox is faster to solve than inverting a fixed target.
Our collision based proof-of-work more generally improves the Prover's random oracle query complexity when applied in the NIZK setting as well. In addition to reducing the query complexity of Fischlin's Prover, for a special class of Sigma protocols we can for the first time closely match a new lower bound we present.
Finally we extend Fischlin's technique so that it applies to a more general class of strongly-sound Sigma protocols, which includes the OR composition. We achieve this by carefully randomizing Fischlin's technique---we show that its current deterministic nature prevents its application to certain multi-witness languages.
Megumi Ando, Miranda Christ, Anna Lysyanskaya, Tal Malkin
In this paper, we initiate a formal treatment of onion routing in a setting with multiple runs over a dynamic network with churn. We provide the following contributions.
-We define the cryptographic primitive of poly onion encryption, which is appropriate for a setting with churn. This primitive is inspired by duo onions, introduced by Iwanik, Klonowski, and Kutylowski (Communications and Multimedia Security, 2005) towards improving onion delivery rate. We generalize the idea, change it to add auxiliary helpers towards supporting better security, and propose formal definitions.
-We construct an instantiation of poly onion encryption based on standard cryptographic primitives (CCA secure public key encryption with tags, PRP, MAC, and secret sharing). Our construction is secure against an active adversary, and is parameterized to allow flexible instantiations supporting a range of corruption thresholds and churn limits.
-We formally model anonymous onion routing for multiple runs in the setting with churn, including a definition of strong anonymity, where the adversary has CCA-like access to oracles for generating and processing onions.
-We prove that if an onion routing protocol satisfies a natural condition we define ("simulatability"), then strong single-run anonymity implies strong multiple-run anonymity. This condition is satisfied by existing onion routing schemes, such as the $\Pi_p$ protocol of Ando, Lysyanskaya, and Upfal (ICALP 2018). As a consequence, these schemes are anonymous also for multiple runs (although not when there is churn).
-We provide an anonymous routing protocol, "Poly $\Pi_p$," and prove that it is anonymous in the setting with churn, against a passive adversary. We obtain this construction by using an instance of our poly onion encryption within the $\Pi_p$ protocol.
Lin You, Zhuobiao Wang, Gengran Hu, Chengtang Cao
Lin You, Xinhua Zhang, Gengran Hu, Longbo Han
Suparna Kundu, Jan-Pieter D’Anvers, Michiel Van Beirendonck, Angshuman Karmakar, Ingrid Verbauwhede
Zhonghui Ge, Yi Zhang, Yu Long, Dawu Gu
In 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.