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24 August 2023
Ashwin Jha, Mustafa Khairallah, Mridul Nandi, Abishanka Saha
Tianyi Liu, Tiancheng Xie, Jiaheng Zhang, Dawn Song, Yupeng Zhang
In this work, we improve the scalability of these techniques by proposing new schemes of fully distributed ZKPs. Our schemes can improve the efficiency and the scalability of ZKPs using multiple machines, while the communication among the machines is minimal. With our schemes, the ZKP generation can be distributed to multiple participants in a model similar to the mining pools. Our protocols are based on Plonk, an efficient zero-knowledge proof system with a universal trusted setup. The first protocol is for data-parallel circuits. For a computation of $M$ sub-circuits of size $T$ each, using $M$ machines, the prover time is $O(T\log T + M \log M)$, while the prover time of the original Plonk on a single machine is $O(MT\log (MT))$. Our protocol incurs only $O(1)$ communication per machine, and the proof size and verifier time are both $O(1)$, the same as the original Plonk. Moreover, we show that with minor modifications, our second protocol can support general circuits with arbitrary connections while preserving the same proving, verifying, and communication complexity. The technique is general and may be of independent interest for other applications of ZKP.
We implement Pianist (Plonk vIA uNlimited dISTribution), a fully distributed ZKP system using our protocols. Pianist can generate the proof for 8192 transactions in 313 seconds on 64 machines. This improves the scalability of the Plonk scheme by 64$\times$. The communication per machine is only 2.1 KB, regardless of the number of machines and the size of the circuit. The proof size is 2.2 KB and the verifier time is 3.5 ms. We further show that Pianist has similar improvements for general circuits. On a randomly generated circuit with $2^{25}$ gates, it only takes 5s to generate the proof using 32 machines, 24.2$\times$ faster than Plonk on a single machine.
Yuval Ishai, Aayush Jain, Paul Lou, Amit Sahai, Mark Zhandry
A necessary condition for the feasibility of wiretap coding is that $\mathsf{ChB}$ is not a degradation of $\mathsf{ChE}$, namely Eve cannot simulate Bob’s view. While insufficient in the information-theoretic setting, a recent work of Ishai, Korb, Lou, and Sahai (Crypto 2022) showed that the non-degradation condition is sufficient in the computational setting, assuming idealized flavors of obfuscation. The question of basing a similar feasibility result on standard cryptographic assumptions was left open, even in simple special cases.
In this work, we settle the question for all discrete memoryless channels where the (common) input alphabet of $\mathsf{ChB}$ and $\mathsf{ChE}$ is binary, and with arbitrary finite output alphabet, under standard (sub-exponential) hardness assumptions: namely those assumptions that imply indistinguishability obfuscation (Jain-Lin-Sahai 2021, 2022), and injective PRGs. In particular, this establishes the feasibility of computational wiretap coding when $\mathsf{ChB}$ is a binary symmetric channel with crossover probability $p$ and $\mathsf{ChE}$ is a binary erasure channel with erasure probability $e$, where $e>2p$.
On the information-theoretic side, our result builds on a new polytope characterization of channel degradation for pairs of binary-input channels, which may be of independent interest.
Kanav Gupta, Neha Jawalkar, Ananta Mukherjee, Nishanth Chandran, Divya Gupta, Ashish Panwar, Rahul Sharma
Sarah Arpin, James Clements, Pierrick Dartois, Jonathan Komada Eriksen, Péter Kutas, Benjamin Wesolowski
We also consider the question in terms of quaternion algebras. We provide algorithms which compute an embedding of a fixed imaginary quadratic order into a maximal order of the quaternion algebra ramified at $p$ and $\infty$. We provide code implementations in Sagemath which is efficient for finding embeddings of imaginary quadratic orders of discriminants up to $O(p)$, even for cryptographically sized $p$.
Florian Hirner, Michael Streibl, Ahmet Can Mert, Sujoy Sinha Roy
Huina Li, Le He, Shiyao Chen, Jian Guo, Weidong Qiu
Noam Mazor
When the oracle function is injective or a permutation, Merkle’s Puzzles has perfect completeness. That is, it is certain that the protocol results in agreement between the parties. However, without such an assumption on the random function, there is a small error probability, and the parties may end up holding different keys. This fact raises the question: Is there a key-agreement protocol with perfect completeness and super-linear security in the ROM?
In this paper we give a positive answer to the above question, showing that changes to the query distribution of the parties in Merkle’s Puzzles, yield a protocol with perfect completeness and roughly the same security.
Steve Thakur
We use the KZG10 polynomial commitment scheme, which allows for a universal updateable CRS linear in the circuit size. In keeping with our recent work ([Th23]), we have used the monomial basis since it is compatible with any sufficiently large prime scalar field. In settings where the scalar field has a suitable smooth order subgroup, the techniques can be efficiently ported to a Lagrange basis.
The proof size is constant, as is the verification time which is dominated by a single pairing check. For committed vectors of length $n$, the proof generation is $O(n\cdot \log(n))$ and is dominated by the $\mathbb{G}_1$-MSMs and a single sum of a few polynomial products over the prime scalar field via multimodular FFTs.
Johanna Loyer
David Chaum, Bernardo Cardoso, William Carter, Mario Yaksetig, Baltasar Aroso
Unlike traditional sampling approaches that select a subset of the network to run consensus on behalf of the network and disseminate the outcome, Phoenixx still requires participation of the whole network. The endorsers, however, assume a special role as they confirm that at least $2f+1$ validators are in agreement and issue a compressed certificate, attesting the network reached a decision. Phoenixx achieves linear communication complexity, while maintaining safety, liveness, and optimistic responsiveness, without using threshold signatures.
Diego F. Aranha, Benjamin Salling Hvass, Bas Spitters, Mehdi Tibouchi
21 August 2023
Technical University of Darmstadt, Germany
The Cryptography and Privacy Engineering Group (ENCRYPTO) @CS Department @Technical University of Darmstadt offers a fully funded position as Doctoral Researcher (Research Assistant/PhD Student) in Cryptography and Privacy Engineering to be filled as soon as possible and initially for 3 years with the possibility of extension.
Job description:You'll work in the collaborative research center CROSSING funded by the German Research Foundation (DFG). In our project E4 Compiler for Privacy-Preserving Protocols, we build compilers to automatically generate optimized MPC protocols for privacy-preserving applications. See https://encrypto.de/CROSSING for details. As PhD@ENCRYPTO, you primarily focus on your research aiming to publish&present the results at top venues.
We offer:We demonstrate that privacy is efficiently protectable in real-world applications via cryptographic protocols. Our open and international working environment facilitates excellent research in a sociable team. TU Darmstadt is a top research university for IT security, cryptography and CS in Europe. Darmstadt is a very international, livable and well-connected city in the Rhine-Main area around Frankfurt.
Your profile:- Completed Master's degree (or equivalent) at a top university with excellent grades in IT security, computer science, or a similar area.
- Extensive knowledge in applied cryptography/IT security and very good software development skills. Knowledge in cryptographic protocols (ideally MPC) is a plus.
- Experience and interest to engage in teaching.
- Self-motivated, reliable, creative, can work independently, and striving to do excellent research.
- Our working language is English: Able to discuss/write/present scientific results in English. German is beneficial but not required.
Closing date for applications:
Contact: Thomas Schneider (application@encrypto.cs.tu-darmstadt.de)
More information: https://encrypto.de/2023-CROSSING
Technical University of Darmstadt, Germany
The Cryptography and Privacy Engineering Group (ENCRYPTO) @Department of Computer Science @TU Darmstadt offers a fully funded position for a Postdoctoral Researcher, to be filled asap and initially til January 31, 2025 with the potential of extension.
Our mission is to demonstrate that privacy can be efficiently protected in real-world applications via cryptographic protocols.TU Darmstadt is located in the center of Germany and is a top research university for IT security, cryptography, and computer science. No German language skills are necessary and we established a hybrid working mode flexibly combining mobile work and in-presence time in office depending on individual preferences.
Job description:As postdoc @ENCRYPTO, your primary focus is on collaborations with our PhDs and external international collaborators for cutting-edge research in applied cryptography as well as the publication and presentation of the results at top-tier security and cryptography conferences/journals. In our ERC-funded project PSOTI, we develop protocols for privately processing data among untrusted service providers using MPC. Examples are privacy-preserving alternatives for common applications such as email, file sharing, and forms. Also, the active research field of PPML is of high relevance for our group.
Your profile- Completed PhD degree (or equivalent) at a top university in IT security, computer science, applied mathematics, electrical engineering, or a similar area
- Publications at top venues (CORE rank A*/A) for IT security/applied cryptography (e.g., EUROCRYPT, S&P, CCS, NDSS, USENIX SEC), ideally on cryptographic protocols and secure computation
- Experience in software development, project management and supervising students
- Self-motivated, reliable, creative, team-minded, and want to do excellent research on challenging scientific problems with practical relevance
- The working language at ENCRYPTO is English, so you must be able to discuss/write/present scientific results in English, whereas German is not required.
Closing date for applications:
Contact: Thomas Schneider (application@encrypto.cs.tu-darmstadt.de)
More information: https://encrypto.de/POSTDOC
Research Institute CODE, Universität der Bundeswehr München, Germany
The Research Institute CODE (https://www.unibw.de/code), established in 2017, with currently 15 professorships and over 130 researchers, is being expanded to one of the largest European research institutes for cyber security.
For a newly established professorship in Cryptography, Daniel Slamanig is seeking multiple PhD and Post-Doc researchers. Relevant topics include:- Public-key cryptographic primitives
- Malleable and updatable cryptography
- Foundations and applications of privacy-preserving cryptography
- Post-quantum cryptography
- (Non-interactive) Zero-knowledge proofs and zk-SNARKs
- Real-world cryptography
Candidates are expected to do cutting edge research in cryptography. We offer the opportunity to engage with research projects and international partners from academia and industry. Candidates will also gain experience with supporting teaching activities.
Requirements:
- Master's degree (or equivalent) or PhD in Mathematics, Computer Science, Information Security, or a similar discipline.
- PostDoc candidates must have a strong track record (ideally with publications at IACR conferences and/or the top 4 security conferences) and good academic writing and presentation skills.
- High motivation for research work and ability to work independently.
- Good organisation and communication skills.
- Eager to disseminate research results through publications and presentations at top-tier conferences.
- Fluency in written and spoken English (German desirable but not required).
How to apply? Send a mail to Daniel Slamanig with subject line "Application UniBWM" including your cover/motivation letter, CV, transcripts of grades, and references.
Closing date for applications: Applications will be reviewed until the positions are filled.
Closing date for applications:
Contact: Daniel Slamanig (daniel.slamanig [AT] gmail.com)
More information: https://danielslamanig.info/
National Sun Yat-sen University, Department of Computer Science and Engineering; Kaohsiung, Taiwan
Responsibilities: Apart from academic work, the student must involve in several activities in a group or individually, such as (not limited to):
Requirements: Apart from the university's basic admission policies (https://cse.nsysu.edu.tw/?Lang=en), students are desired to have the following key requirements:
Scholarship:
What students can expect:
What the supervisor can expect: Apart from academic and research works, students are expected to have
Closing date for applications:
Contact: Dr. Arijit Karati (arijit.karati@mail.cse.nsysu.edu.tw)
National Sun Yat-sen University, Department of Computer Science and Engineering; Kaohsiung, Taiwan
Essential Qualifications:
Closing date for applications:
Contact: Dr. Arijit Karati (arijit.karati@mail.cse.nsysu.edu.tw)
Monash University, Melbourne, Australia
- Post-quantum cryptography (based on lattices and/or hash) and its applications
- Privacy-enhancing technologies (e.g. zero-knowledge proofs) and their applications
- highly competitive tuition fee and stipend scholarships
- opportunities to collaborate with leading academic and industry experts in the related areas
- opportunities to participate in international grant-funded projects
- collaborative and friendly research environment
- an opportunity to live/study in one of the most liveable and safest cities in the world
Requirements. A strong mathematical and cryptography background is required. Some knowledge/experience in coding (for example, Python, C/C++, SageMath) is a plus. Candidates must have completed (or be about to complete within the next 6 months) a significant research component either as part of their undergraduate (honours) degree or masters degree. They should have excellent English verbal and written communication skills.
How to apply. Please fill in the following form (also clickable from the advertisement title): https://docs.google.com/forms/d/e/1FAIpQLSetFZLvDNug5SzzE-iH97P9TGzFGkZB-ly_EBGOrAYe3zUYBw/viewform?usp=sf_link
Closing date for applications:
Contact: Ron Steinfeld
More information: https://docs.google.com/forms/d/e/1FAIpQLSetFZLvDNug5SzzE-iH97P9TGzFGkZB-ly_EBGOrAYe3zUYBw/viewform?usp=sf_link
Monash University, Melbourne, Australia
Closing date for applications:
Contact: Rafael Dowsley Email: rafael.dowsley@monash.edu
Queen's University Belfast
Closing date for applications:
Contact: Arnab Kumar Biswas
More information: https://www.qub.ac.uk/courses/postgraduate-research/phd-opportunities/a-trusted-execution-environment-based-framework-for-securing-legacy-embedded-systems.html