IACR News
Here you can see all recent updates to the IACR webpage. These updates are also available:
10 October 2022
Andre Esser, Floyd Zweydinger
Our trade-offs yield significant running time improvements for every fixed memory limit $M\geq2^{0.091n}$. Furthermore, we interpolate to the running times of the fastest known algorithms when memory is not limited. Technically, our design introduces a pruning strategy to the construction by Becker-Coron-Joux (BCJ) that allows for an exponentially small success probability. We compensate for this reduced probability by multiple randomized executions. Our main improvement stems from the clever reuse of parts of the computation in subsequent executions to reduce the time complexity per iteration.
As an application of our construction, we derive the first non-trivial time-memory trade-offs for Information Set Decoding (ISD) algorithms. Our new algorithms improve on previous (implicit) trade-offs asymptotically as well as practically. Moreover, our optimized implementation also improves on running time, due to reduced memory access costs. We demonstrate this by obtaining a new record computation in decoding quasi-cyclic codes (QC-3138). Using our newly obtained data points we then extrapolate the hardness of suggested parameter sets for the NIST PQC fourth round candidates McEliece, BIKE and HQC, lowering previous estimates by up to 6 bits and further increasing their reliability.
Andre Esser
In this work we first revisit the Both-May algorithm, by giving a clean exposition and a corrected analysis. We confirm the claim by Carrier et al. that the initial analysis is flawed. However, we find that the algorithm still (slightly) improves on time complexity and significantly improves on memory complexity over previous algorithms. Our first main contribution is therefore to set the correct baseline for further improvements.
As a second main contribution we then show how to improve on the Both-May algorithm, lowering the worst case running time in the full distance decoding setting to $2^{0.0948n}$. We obtain even higher time complexity gains for small rates, shifting the break even point with RLPN decoding to rate $\frac{k}{n}=0.25$. Moreover, we significantly improve on memory for all rates $\frac{k}{n}<0.5$. We obtain our improvement by introducing a novel technique to combine the list construction step and the list filtering step commonly applied by ISD algorithms. Therefore we treat the nearest neighbor routine in a non-blackbox fashion which allows us to embed the filtering into the nearest neighbor search. In this context we introduce the fixed-weight nearest neighbor problem, and propose a first algorithm to solve this problem. Besides resulting in an improved decoding algorithm this opens the direction for further improvements, since any faster algorithm for solving this fixed-weight nearest neighbor variant is likely to lead to further improvements of our ISD algorithm.
Trey Li
Divesh Aggarwal, Marshall Ball, Maciej Obremski
Over the last decade, non-malleable codes have been studied for a wide variety of tampering families. Among the most well studied of these is the split-state family of tampering channels, where the codeword is split into two or more parts and each part is tampered independently.
We survey various constructions and applications of non-malleable codes in the split-state model.
07 October 2022
Coinbase
We have a senior/staff cryptography researcher position available in the Blockchain Security team at Coinbase.
Full description available here:
- Senior role: https://www.coinbase.com/careers/positions/4582729
- Staff role: https://www.coinbase.com/careers/positions/4586906
Please reach out to me at [s] [last name] @pm.me if you have any questions.
Closing date for applications:
Contact: Shashank Agrawal
More information: https://www.coinbase.com/careers/positions/4582729
Aarhus University, Department of Computer Science, Denmark
Closing date for applications:
Contact: Head of Department, Professor Kaj Grønbæk kgronbak@cs.au.dk.
More information: https://www.au.dk/om/stillinger/job/full-professorship-in-cryptography-and-security-at-computer-science-aarhus-university
The University of Alabama in Huntsville
The Department of Mathematical Sciences offers academic programs that lead to Bachelor's and Master's degrees in Mathematics and a Doctor of Philosophy degree in Applied Mathematics. It has over 18 full-time faculty members whose expertise covers the essential topics in applied mathematics. The successful applicant will be expected to teach undergraduate and graduate courses, advise undergraduate and graduate students, and engage in funded research.
ABOUT THE UNIVERSITY: UAH is a Very High Research Activity (R1) university that provides academic and research programs in the Colleges of Arts, Humanities, and Social Sciences, Business, Education, Engineering, Nursing, Professional Studies, and Science. Huntsville has one of the greatest per capita incomes and living standards in the Southeast. It houses NASA's Marshall Space Flight Hub and is a national aerospace and high technology research center.
APPLICATION PROCEDURE AND DEADLINE: To apply for the position, please submit the following required application materials electronically no later than January 28, 2023: 1) Cover letter 2) Curriculum vitae 3) Research statement 4) Teaching statement 5) Transcripts 6) Three reference letters to the Search Committee through Dr. Toka Diagana, mathchair@uah.edu. Please refer to the log number: 23-24-583.
A formal review of the applications will begin on January 17, 2023, and continue until the position is filled.
UAH mandates that all employees maintain compliance with current federal regulations.
The University of Alabama in Huntsville is an affirmative action/equal opportunity employer of minorities/ females/veterans/disabled.
Closing date for applications:
Contact: Dr. Toka Diagana, e-mail: mathchair@uah.edu. Please refer to the log number: 23-24-583.
More information: https://www.uah.edu/hr/careers/faculty-careers#COS
PACY Lab, RI CODE, Universität der Bundeswehr Munich, Germany
We are looking for a bright postdoc (or a PhD student nearing completion) with expertise in any of the following areas:
- Confidential computing (ZKP, FHE, MPC, ABC techniques)
- Distributed cryptography (key generation, signatures, encryption)
- Secure and private messaging (authentication, key exchange)
- Design of post-quantum secure cryptographic protocols
The position is available for immediate start, funded at federal salary levels TV-ÖD E13/14 (~50k to 65k EUR p.a. depending on qualifications and experience). Initial contract for 2 years with a possibility of extension. (Due to the nature of funding restrictions on the eligibility of some candidates may apply.)
Requirements:
- Completed PhD in cryptography, information security, computer science or mathematics.
- Alternatively, PhD students with a relevant Master degree nearing PhD completion.
- Strong background knowledge / experience in privacy-enhancing cryptography (research and development)
- Relevant publications in top cryptography / security / privacy venues
- Fluency in written and spoken English.
Closing date for applications:
Contact: Prof. Mark Manulis, mark.manulis AT unibw.de
More information: https://www.unibw.de/pacy-en/
KU Leuven
The area is interpreted broadly, and covers for example security and privacy, reliability and resilience of digital services, of software products and of internet-based systems.
Closing date for applications:
Contact: Prof. dr. ir. Wouter Joosen chair of DistriNet Wouter.Joosen@kuleuven.be +32 16 32 76 53
Prof. dr. ir. Stefan Vandewalle chair of Computer Science Stefan.Vandewalle@kuleuven.be +32 16 32 76 54
More information: https://distrinet.cs.kuleuven.be/jobs/PDF/Flyer_ZAP-2022-48_Sep22.pdf
05 October 2022
Thomas Pornin
In this paper, we show how to make a prime order group abstraction out of standard binary curves. We describe a new canonical compression scheme that yields a canonical and compact encoding. We also describe complete formulas for operations on the group. The formulas have no exceptional case, and are furthermore faster than previously known complete and incomplete formulas (general point addition in cost 8M+2S+2mb on all curves, 7M+2S+2mb on half of the curves). We also show how the same formulas can be applied to computations on the entire original curve, if full backward compatibility with standard curves is needed. Finally, we implemented our method over the standard NIST curves B-233 and K-233. Our strictly constant-time code achieves generic point multiplication by a scalar on curve K-233 in as little as 29600 clock cycles on an Intel x86 CPU (Coffee Lake core).
Venkata Koppula, Brent Waters, Mark Zhandry
Shujiao Cao, Rui Xue
We propose two variants of one-way quantum state generator, which we call them the weak one-way quantum state generator and distributionally one-way quantum state generator, and show the equivalence among these three primitives.
The distributionally one-way quantum state generator from average-case hardness assumption of a promise problem belongs to \textsf{QSZK} is obtained, and hence a construction of one-way quantum state generator.
A direct construction of quantum bit commitment with statistical binding (sum-binding) and computational hiding from the average-case hardness of a complete problem of $\textsf{QSZK}$.
To show the non-triviality of the constructions above, a quantum oracle $\mathcal{U}$ is devised relative to which such promise problem in $\textsf{QSZK}$ doesn't belong to $\mathsf{QMA}^{\mathcal{U}}$.
Our results present the first non-trivial construction of one-way quantum state generator from the hardness assumption of complexity class, and give another evidence that one-way quantum state generator probably requires less than post-quantum secure one-way function.
Anton A. Sokolov
Tao Lu, Chengkun Wei, Ruijing Yu, Yi Chen, Li Wang, Chaochao Chen, Zeke Wang, Wenzhi Chen
Yael Tauman Kalai, Alex Lombardi, Vinod Vaikuntanathan, Daniel Wichs
Trey Li
Bolton Bailey, Andrew Miller
Aayush Jain, Huijia Lin, Ji Luo
We present the first PHFE scheme for RAMs based on the necessary assumption of FE for circuits. It achieves nearly optimal succinctness and efficiency:
* The secret keys $\mathsf{sk}_f$ are of (optimal) *constant size*, independent of the description size $|f|$ of the function tied to it.
* The ciphertexts $\mathsf{ct}_x(y)$ have (nearly optimal) *rate-2* dependency on the private input length $|y|$ and (optimal) independency of the public input length $|x|$.
* Decryption is efficient, running in time linear in the instance running time $T$ of the RAM computation, in addition to the input and function sizes, i.e., ${T_{\mathsf{Dec}}=(T+|f|+|x|+|y|)\operatorname{poly}(\lambda)}$.
Our construction significantly improves upon the asymptotic efficiency of prior schemes. As a corollary, we obtain the first ABE scheme with both constant-size keys and constant-size ciphertexts, and the best-possible decryption time matching an existing lower bound.
We show barriers to further improvement on the asymptotic efficiency of (PH-)FE. We prove the first unconditional space-time trade-off for (PH-)FE. *No* secure (PH-)FE scheme can have both key size and decryption time sublinear in the function size $|f|$, and *no* secure PHFE scheme can have both ciphertext size and decryption time sublinear in the public input length $|x|$. These space-time trade-offs apply even in the simplest selective 1-key 1-ciphertext secret-key setting. Furthermore, we show a conditional barrier towards achieving the optimal decryption time ${T_{\mathsf{Dec}}=T\operatorname{poly}(\lambda)}$ — any such (PH-)FE scheme implies a primitive called secret-key doubly efficient private information retrieval (SK-DE-PIR), for which so far the only known candidates rely on new and non-standard hardness conjectures.
Daniel Escudero, Vipul Goyal, Antigoni Polychroniadou, Yifan Song
Jakub Klemsa
Among existing FHE schemes, in this contribution we focus on the TFHE Scheme by Chillotti et al., which currently achieves the best evaluation times for generic functions. To be instantiated, TFHE however requires an extensive set of parameters. These parameters affect several aspects, including but not limited to the cleartext size, the bit-security level, the probability of errors and also the evaluation time. We propose, implement and evaluate a (semi-)automated approach to generate a set of TFHE parameters with particular respect to the evaluation time, given just the desired security level, cleartext precision, and a parameter that relates to the properties of the evaluated function $f$. With our tool, we re-generate some of the existing TFHE parameters, while achieving up to 39% better execution times in an equivalent setup.