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24 April 2023
James Bartusek, Dakshita Khurana, Akshayaram Srinivasan
First, we construct a one-shot (i.e., single message) string oblivious transfer (OT) protocol with random receiver bit in the shared EPR pairs model, assuming the (sub-exponential) hardness of LWE. Building on this, we show that {\em secure teleportation through quantum channels} is possible. Specifically, given the description of any quantum operation $Q$, a sender with (quantum) input $\rho$ can send a single classical message that securely transmits $Q(\rho)$ to a receiver. That is, we realize an ideal quantum channel that takes input $\rho$ from the sender and provably delivers $Q(\rho)$ to the receiver without revealing any other information. This immediately gives a number of applications in the shared EPR pairs model: (1) non-interactive secure computation of unidirectional \emph{classical} randomized functionalities, (2) NIZK for QMA from standard (sub-exponential) hardness assumptions, and (3) a non-interactive \emph{zero-knowledge} state synthesis protocol.
Next, we construct a two-round (round-optimal) secure multiparty computation protocol for classical functionalities in the shared EPR pairs model that is \emph{unconditionally-secure} in the (quantum-accessible) random oracle model.
Classically, both of these results cannot be obtained without some form of correlated randomness shared between the parties, and the only known approach is to have a trusted dealer set up random (string) OT correlations. In the quantum world, we show that shared EPR pairs (which are simple and can be deterministically generated) are sufficient. At the heart of our work are novel techniques for making use of entangling operations to generate string OT correlations, and for instantiating the Fiat-Shamir transform using correlation-intractability in the quantum setting.
Lennart Braun, Moritz Huppert, Nora Khayata, Thomas Schneider, Oleksandr Tkachenko
In this paper, we present FUSE: A Framework for Unifying and Optimizing Secure Multi-Party Computation Implementations with Efficient Circuit Storage. FUSE provides a flexible intermediate representation (FUSE IR) that can be used across different platforms and in different programming languages, including C/C++, Java, Rust, and Python. We aim at making MPC tools more interoperable, removing the tight coupling between high-level compilers for MPC and specific MPC protocol engines, thus driving knowledge transfer. Our framework is inspired by the widely known LLVM compiler framework. FUSE is portable, extensible, and it provides implementation-agnostic optimizations.
As frontends, we implement HyCC (CCS'18), the Bristol circuit format, and MOTION (TOPS'22), meaning that these can be automatically converted to FUSE IR. We implement several generic optimization passes, such as automatic subgraph replacement and vectorization, to showcase the utility and efficiency of our framework. Finally, we implement as backends MOTION and MP-SPDZ (CCS'20), so that FUSE IR can be run by these frameworks in an MPC protocol, as well as other useful backends for JSON output and the DOT language for graph visualization. With FUSE, it is possible to use any implemented frontend with any implemented backend and vice-versa. FUSE IR is not only efficient to work on and much more generic than any other format so far -- supporting, e.g., function calls, hybrid MPC protocols as well as user-defined building blocks, and annotations -- while maintaining backwards-compatibility, but also compact, with smaller storage size than even minimalistic formats such as Bristol already for a few hundred operations.
Liliya Kraleva, Mohammad Mahzoun, Raluca Posteuca, Dilara Toprakhisar, Tomer Ashur, Ingrid Verbauwhede
Bhuvnesh Chaturvedi, Anirban Chakraborty, Ayantika Chatterjee, Debdeep Mukhopadhyay
Jonathan Bootle, Vadim Lyubashevsky, Ngoc Khanh Nguyen, Alessandro Sorniotti
James Bartusek, Dakshita Khurana, Giulio Malavolta, Alexander Poremba, Michael Walter
Alia Umrani, Paolo Palmieri
In this paper, we substantially extend Hung et al.’s multireceiver certificateless encryption scheme to a Multireceiver Certificateless Signcryption (MCLS) scheme that provides confidentiality along with authentication. We show that, as compared to Hung et al.’s encryption scheme, our signcryption scheme requires only three additional multiplication operations for signcryption and unsigncryption phases. Whereas, the signcryption cost is linear with the number of designated receivers while the unsigncryption cost remains constant for each designated receiver. We compare the results with other existing single receiver and multireceiver signcryption schemes in terms of number of operations, exemption of key escrow problem, and public key settings. The scheme proposed in this paper is more efficient for single and multireceiver signcryption schemes while providing exemption from the key escrow problem, and working in certificateless public key settings.
Ittai Abraham, Gilad Asharov, Shravani Patil, Arpita Patra
Compared to state-of-the-art MPC protocols in the player elimination framework [Beerliova and Hirt TCC'08, and Goyal, Liu, and Song CRYPTO'19], for $C>n^3$ and $D \ll n$, our results significantly improve the run time from $\Omega(n+D)$ to expected $O(D)$ while keeping communication complexity at $O(Cn\log n)$.
Compared to state-of-the-art MPC protocols that obtain an expected $O(D)$ time complexity [Abraham, Asharov, and Yanai TCC'21], for $C>n^3$, our results significantly improve the communication complexity from $O(Cn^4\log n)$ to $O(Cn\log n)$ while keeping the expected run time at $O(D)$.
One salient part of our technical contribution is centered around a new primitive we call "detectable secret sharing". It is perfectly-hiding, weakly-binding, and has the property that either reconstruction succeeds or $O(n)$ parties are (privately) detected. On the one hand, we show that detectable secret sharing is sufficiently powerful to generate multiplication triplets needed for MPC. On the other hand, we show how to share $p$ secrets via detectable secret sharing with communication complexity of just $O(n^4\log n+p \log n)$. When sharing $p\geq n^4$ secrets, the communication cost is amortized to just $O(1)$ field elements per secret.
Our second technical contribution is a new Verifiable Secret Sharing protocol that can share $p$ secrets at just $O(n^4\log n+pn\log n)$ word complexity. When sharing $p\geq n^3$ secrets, the communication cost is amortized to just $O(n)$ filed elements per secret. The best prior required $\Omega(n^3)$ communication per secret.
Quan Yuan, Mehdi Tibouchi, Masayuki Abe
Till Gehlhar, Felix Marx, Thomas Schneider, Ajith Suresh, Tobias Wehrle, Hossein Yalame
To address this gap, we introduce SAFEFL, a secure multiparty computation (MPC)-based framework designed to assess the efficacy of FL techniques in addressing both privacy inference and poisoning attacks. The heart of the SAFEFL framework is a communicator interface that enables PyTorch-based implementations to utilize the well established MP-SPDZ framework, which implements various MPC protocols. The goal of SAFEFL is to facilitate the development of more efficient FL systems that can effectively address privacy inference and poisoning attacks.
Reza Hooshmand
Ren Taguchi, Atsushi Takayasu
Srinath Setty, Justin Thaler, Riad Wahby
Unlike HyperPlonk, SuperSpartan can prove uniform instances of CCS (including AIR) without requiring a linear-time preprocessing for the verifier. SuperSpartan for AIR is the first SNARK for AIR with a linear-time prover, transparent and sublinear-time pre-processing, polylogarithmic proof size, and plausible post-quantum security. In particular, SuperSpartan for AIR provides a faster prover than existing transparent SNARKs for AIR (which are sometimes referred to as STARKs).
Estuardo Alpirez Bock, Gustavo Banegas, Chris Brzuska, Łukasz Chmielewski, Kirthivaasan Puniamurthy, Milan Šorf
Akın Ünal
Concretely, against PRGs $F : \{0,1\}^n\rightarrow \{0,1\}^{n^{1+e}}$ we will give an algebraic attack whose time complexity is bounded by \[\exp(O(\log(n)^{\deg F /(\deg F - 1)} \cdot n^{1-e/(\deg F -1)} ))\] and whose advantage is at least $1 - o(1)$ in the worst case.
To the best of the author's knowledge, this attack outperforms current attacks on the pseudorandomness of local random functions with guaranteed noticeable advantage and gives a new baseline algorithm for local PRGs. Furthermore, this is the first subexponential attack that is applicable to polynomial PRGs of constant degree over fields of any size with a guaranteed noticeable advantage.
Wouter Castryck, Marc Houben, Simon-Philipp Merz, Marzio Mula, Sam van Buuren, Frederik Vercauteren
As an application, we identify weak instances of class group actions on elliptic curves assuming the degree of the secret isogeny is known. More in detail, we show that if $m^2 \mid \Delta_\mathcal{O}$ for some prime power $m$ then given two primitively $\mathcal{O}$-oriented elliptic curves $(E, \iota)$ and $(E',\iota') = [\mathfrak{a}] E,\iota)$ connected by an unknown invertible ideal $\mathfrak{a} \subseteq \mathcal{O}$, we can recover $\mathfrak{a}$ essentially at the cost of a discrete logarithm computation in a group of order $m^2$, assuming the norm of $\mathfrak{a}$ is given and is smaller than $m^2$. We give concrete instances, involving ordinary elliptic curves over finite fields, where this turns into a polynomial time attack.
Finally, we show that these self-pairings simplify known results on the decisional Diffie-Hellman problem for class group actions on oriented elliptic curves.
20 April 2023
Utrecht University, Department of Information and Computing Sciences; Utrecht, Netherlands
In this project, you will develop foundations and practical techniques to build software systems with reliable security guarantees. Depending on your background and interests, this project can focus on different security problems, including, for example, memory safety, software sandboxing, information-flow control systems, and defenses against side-channel and Spectre attacks.
Interested? Click on the title to know more and apply!
Deadline: 16 May 2023
Duration: 5 Years
Apply here: https://www.uu.nl/en/organisation/working-at-utrecht-university/jobs/phd-position-in-language-based-security-10-fte
Closing date for applications:
Contact: Marco Vassena, https://webspace.science.uu.nl/mvassena
More information: https://www.uu.nl/en/organisation/working-at-utrecht-university/jobs/phd-position-in-language-based-security-10-fte
University of Luxembourg
The CryptoLux group of the University of Luxembourg has a vacancy for a post-doctoral researcher in the area of security/privacy of blockchains and smart contracts. The successful candidate will contribute to a research project entitled Advanced Cryptography for Finance and Privacy (CryptoFin), which is funded by the Fonds National de la Recherche (FNR). Starting in September 2023, CryptoFin will run over a period of 3 years and be carried out in collaboration with the cryptography teams of Stanford University and Ethereum foundation. The mission of the CryptoFin project is to develop innovative solutions for some of the most pressing research problems in the blockchain domain, especially in the context of layer-2 protocols for off-chain transactions and the design of advanced cryptographic techniques like verifiable delay functions, proof-of-X systems with special features, and new MPC/SNARK-friendly primitives.
Candidates must hold a Ph.D. degree in cryptography, IT security, or a related field. Preference will be given to candidates with a strong publication record that includes at least one paper at an IACR conference/workshop or one of the top-4 security conferences. Experience in blockchains and/or smart contracts is a plus. Candidates with an interest to conduct research in one of the following areas are particularly encouraged to apply:
- Applied cryptography (especially design/analysis of symmetric cryptosystems)
- Cryptofinance and cryptoeconomics
- Privacy and anonymity on the Internet
The position is initially offered for 1 year, but an extension by 2 years is possible. The University of Luxembourg offers excellent working conditions and a highly competitive salary. Interested candidates are invited to send their application by email to Prof. Alex Biryukov before May 7, 2023 (early submission is encouraged). The application material should contain a cover letter explaining the candidate's research interests, a CV (incl. photo), a list of publications, scans of diploma certificates, and contact details of 3 references.
Closing date for applications:
Contact: Prof. Alex Biryukov (alex.biryukov@uni.lu)
More information: https://cryptolux.org/index.php/Vacancies
University of Luxembourg
The CryptoLux group of the University of Luxembourg has two vacancies for Ph.D. positions in the area of security/privacy of blockchains and smart contracts. The successful candidates will contribute to a research project entitled Advanced Cryptography for Finance and Privacy (CryptoFin), which is funded by the Fonds National de la Recherche (FNR). Starting in September 2023, CryptoFin will run over a period of 3 years and be carried out in collaboration with the cryptography teams of Stanford University and Ethereum foundation. The mission of the CryptoFin project is to develop innovative solutions for some of the most pressing research problems in the blockchain domain, especially in the context of layer-2 protocols for off-chain transactions and the design of advanced cryptographic techniques like verifiable delay functions, proof-of-X systems with special features, and new MPC/SNARK-friendly primitives.
Candidates must hold an M.Sc. degree (or earn an M.Sc. degree before September 2023) in computer science, mathematics, or a related field. Experience in blockchains and/or smart contracts is a plus. Candidates with an interest to conduct research in one of the following areas are particularly encouraged to apply:
- Applied cryptography (especially design/analysis of symmetric cryptosystems)
- Cryptofinance and cryptoeconomics
- Privacy and anonymity on the Internet
Both positions are fully funded and initially offered for 3 years, but an extension to a 4th year is possible. The University of Luxembourg offers excellent working conditions and a highly competitive salary. Interested candidates are invited to send their application by email to Prof. Alex Biryukov before May 7, 2023 (early submission is encouraged). The application material should contain a cover letter explaining the candidate's research interests, a CV (incl. photo), scans of diploma certificates, and contact details of 3 references.
Closing date for applications:
Contact: Prof. Alex Biryukov (alex.biryukov@uni.lu)
More information: https://cryptolux.org/index.php/Vacancies
19 April 2023
- Jung Hee Cheon, for influential contributions to algebraic cryptanalysis and fully homomorphic encryption, as well as outstanding service to IACR and the Asia-Pacific cryptography community.
- Stanisław Jarecki, for significant contributions to the development and standardization of distributed cryptography, as well as for service to IACR.
- Marc Joye, for practical and theoretical contributions to applied and industrial cryptography, and for contributions to IACR.
- Jesper Buus Nielsen, for fundamental contributions to cryptography and for service to IACR.
- Rafael Pass, for fundamental contributions to theoretical cryptography and service to the cryptography community.
- Giuseppe Persiano, for fundamental contributions to non-interactive zero knowledge and searchable encryption, as well as for service to the cryptography community.
- Reihaneh Safavi-Naini, for significant contributions to cryptography and its application to information security, and exemplary service to IACR and the cryptography community.