IACR News
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22 April 2022
Aron Gohr, Friederike Laus, Werner Schindler
In order to see the shared cipher state, we employ a deep neural network similar to the one used by Gohr, Jacob and Schindler to solve the CHES 2018 AES challenge. We modify their architecture to predict the exact bit sequence of the secret-shared cipher state. We find that convergence of training on this task is unsatisfying with the standard encoding of the shared cipher state and therefore introduce a different encoding of the prediction target, which we call the scattershot encoding. In order to further investigate how exactly the scattershot encoding helps to solve the task at hand, we construct a simple synthetic task where convergence problems very similar to those we observed in our side-channel task appear with the naive target data encoding but disappear with the scattershot encoding.
We complete our analysis by showing results that we obtained with a classical method (as opposed to an AI-based method), namely the stochastic approach, that we generalize for this purpose first to the setting of shared keys. We show that the neural network draws on a much broader set of features, which may partially explain why the neural-network based approach massively outperforms the stochastic approach. On the other hand, the stochastic approach provides insights into properties of the implementation, in particular the observation that the $S$-boxes behave very different regarding the easiness respective hardness of their prediction.
Pourandokht Behrouz, Panagiotis Grontas, Vangelis Konstantakatos, Aris Pagourtzis, Marianna Spyrakou
Daniel Fallnich, Shutao Zhang, Tobias Gemmeke
Leizhang Wang, Wenwen Xia, Geng Wang, Baocang Wang, Dawu Gu
Arnaud de Grandmaison, Karine Heydemann, Quentin L. Meunier
Nicolas David, Thomas Espitau, Akinori Hosoyamada
M. Rajululkahf
Băhēm's security is very similar to that of the one-time pad (OTP), except that it does not require the communicating parties the inconvenient constraint of generating a large random pad in advance of their communication. Instead, Băhēm allows the parties to agree on a small pre-shared secret key, such as |k| = 128 bits, and then generate their random pads in the future as they go.
For any operation, be it encryption or decryption, Băhēm performs only 4 exclusive-or operations (XORs) per cleartext bit including its 2 overhead bits. If it takes a CPU 1 cycle to perform an XOR between a pair of 64 bit variables, then a Băhēm operation takes 4 / 8 = 0.5 cycles per byte. Further, all Băhēm's operations are independent, therefore a system with n many CPU cores can perform 0.5 / n cpu cycles per byte per wall-clock time.
While Băhēm has an overhead of 2 extra bits per every encrypted cleartext bit, its early single-threaded prototype implementation achieves a faster /decryption/ than OpenSSL's ChaCha20's, despite the fact that Băhēm's ciphertext is 3 times larger than ChaCha20's. This support that the 2 bit overhead is practically negligible for most applications.
Băhēm's early prototype has a slower /encryption/ time than OpenSSL's ChaCha20 due to its use of a true random number generator (TRNG). However, this can be trivially optimised by gathering the true random bits in advance, so Băhēm gets the entropy conveniently when it runs.
Aside from Băhēm's usage as a provably-secure general-purpose symmetric cipher, it can also be used, in some applications such as password verification, to enhance existing hashing functions to become provably one-way, by using Băhēm to encrypt a predefined string using the hash as the key. A password is then verified if its hash decrypts the Băhēm ciphertext to retrieve the predefined string.
Shaoxuan Zhang, Chun Guo, Qingju Wang
We first extend Kuwakado and Morii's attack against the Even-Mansour cipher (ISITA 2012), and exhibit key recovery attacks against a large class of pseudorandom schemes based on a single call to an $n$-bit permutation, with polynomial $O(n)$ quantum steps. We also show how to overcome restrictions on available quantum data in certain relevant settings.
We then consider TPPR schemes, namely, Two Permutation-based PseudoRandom cryptographic schemes. Using the improved Grover-meet-Simon method of Bonnetain et al. (ASIACRYPT 2019), we show that the keys of a wide class of TPPR schemes can be recovered with $O(n)$ superposition queries and $O(n2^{n/2})$ quantum steps. We also exhibit sub-classes of "degenerated" TPPR schemes that lack certain internal operations, and exhibit more efficient key recovery attacks using either the Simon's algorithm or Chailloux et al.'s algorithm for collision searching (ASIACRYPT 2017). Further using the all-subkeys-recovery idea of Isobe and Shibutani (SAC 2012), our results give rise to key recovery attacks against several recently proposed permutation-based PRFs, as well as the 2-round Even-Mansour ciphers with generic key schedule functions (Chen et al., JoC 2018) and their tweakable variants (Cogliati et al., CRYPTO 2015). From a constructive perspective, our results establish new quantum Q2 security upper bounds for two permutation-based pseudorandom schemes as well as sound design choices.
Harashta Tatimma Larasati, Dedy Septono Catur Putranto, Rini Wisnu Wardhani, Howon Kim
Miguel Ambrona, Anne-Laure Schmitt, Raphael R. Toledo, Danny Willems
Wei Cheng, Sylvain Guilley, Jean-Luc Danger
Relying on our empirical evaluations, we therefore recommend investigating the coding-theoretic properties to find the best linear codes in strengthening instances of code-based masking. As for applications, our attack-based evaluation directly empowers designers, by employing optimal linear codes, to enhance the protection of code-based masking. Our framework leverages simulated leakage traces, hence allowing for source code validation or patching in case it is found to be attackable.
Lin You, Qiang Zhu, Gengran Hu
18 April 2022
University of Clermont Auvergne, France
Topics:
- Cryptographic algorithms and protocols
- Computer networking
- Research on secure Multi-Part Computation (MPC) and cutting-edge technologies to solve security issues in network routing.
- Possible teaching.
- Completion of a Master's degree (or equivalent) in computer science or applied mathematics
- Knowledge in applied cryptography/security and computer networking
- Analytical and problem solving skills.
Deadline: 3 May 2022
Closing date for applications:
Contact: Kevin Atighehchi (kevin.atighehchi@uca.fr), Gérard Chalhoub (gerard.chalhoub@uca.fr)
Aalto University, Department of Mathematics and Systems Analysis, Espoo, Finland
Research experience in cryptography is essential. Additionally, background in algebraic number theory, probability theory, complexity theory and/or machine learning are useful. For a cryptographer, we expect that the candidate has published in IACR conferences, established theoretical computer science venues (STOC/FOCS/APPROX-RANDOM/SODA/PODC) or IT security venues (CCS/S&P/Usenix). The applicant is expected to hold a PhD degree in mathematics or computer science. A research level proficiency in English, both writing and speaking, is expected.
We offer advising related to both algebraic lattices (Camilla Hollanti) and cryptography (Chris Brzuska). Our group offers a diverse, international, and open research environment with an interdisciplinary academic and industrial network. We expect the candidate to significantly shape the research questions which we investigate together as well as to pursue their own research within their existing research network.
The tentative duration of the position is September 2022 — December 2023 (16 months), but a shorter duration or an earlier starting date is negotiable. There is an option to renew the contract subject to acquiring funding (either by the candidate or by the hosts). The initial salary is €3700 and the contract includes occupational health care.
For details, see: https://www.aalto.fi/en/open-positions/postdoctoral-researcher-in-mathematics-or-computer-science-lattice-based
Closing date for applications:
Contact: Camilla Hollanti and Chris Brzuska for scientific questions and Johanna Glader for questions on the application process. (eMail: firstname.lastname@aalto.fi )
More information: https://www.aalto.fi/en/open-positions/postdoctoral-researcher-in-mathematics-or-computer-science-lattice-based
University of Neuchatel, Switzerland
We are looking for a PhD student to join our group on reinforcement learning and decision making under uncertainty more generally, at the University of Neuchatel, Switzerland. We are looking for candidates with a strong research interest in the following fields:
- Theory of differntial privacy.
- Algorithms for differentially private machine learning.
- Algorithms for fairness in machine learning.
- Interactions between machine learning and game theory.
- Inference of human models of fairness or privacy.
The main supervisor will be Chrsitos Dimitrakakis ( https://sites.google.com/site/christosdimitrakakis ) Past research of the group in differential privacy focused on the interaction between Bayesian inference and privacy, and on the derivation of regret bounds for privacy-constrained bandit problems. The student will also have the opportunity to visit and work with other group members at the University of Oslo, Norway and Chalmers University of Technology, Sweden.
Excellent technical skills in calculus, linear algebra, probability as well as competence in at least one programming language is expected. In addition,the doctoral student must have a strong background, as evidenced by their master thesis, in one of the following areas:
- Privacy.
- Theory of computation
- Statistics.
- Game theory.
- Economics.
- Fairness.
- Starting date 1 September 2022 or soon afterwards.
- Application deadline 31 May 2022.
- The PhD is funded, for 4 years, with 25% of the time as teaching assistant.
- A statement of research interests.
- A CV with a list of references.
- Your MSc thesis (or a draft) or another research work demonstrating your academic writing.
- Degree transcripts.
Closing date for applications:
Contact: Christos Dimitrakakis
More information: https://sites.google.com/site/christosdimitrakakis/positions
13 April 2022
April 6, 2022
Statement from the International Association for Cryptologic Research (IACR) Condemning the Russian war in Ukraine
The IACR strongly condemns the unprovoked and unjust war that Russia is waging in Ukraine. We are outraged by the suffering and loss of life that this brutal aggression is inflicting on the Ukrainian People.
While this war continues, the IACR will not hold or plan to hold any conference in Russia, nor will it be affiliated with conferences in Russia.
The IACR fully endorses the following joint statement by the National Academies of G7 States which was published on 2 March 2022:
"The unprovoked attack against Ukraine, a democratic and independent country, is a blatant violation of international law and of core values of humanity. The Russian invasion is an assault on the fundamental principles of freedom, democracy and self-determination, which provide the basis for academic freedom and opportunities for scientific exchange and cooperation.
In this dark hour, our thoughts and deepest sympathy are with the people of Ukraine. We are determined to support the National Academy of Sciences of Ukraine. We stand in solidarity with the scientific community and the scientists in Ukraine.
We acknowledge the Russian scientists and citizens who are ashamed of this attack and speak out against the war.
We call on the Russian leadership to immediately cease all military action against Ukraine and put an end to this war."
Approved by the IACR board of directors, April 6, 2022
12 April 2022
New Jersey Institute of Technology
Successful candidates must have an expert grasp of knowledge of Cybersecurity at all levels, with an emphasis on hands-on applied cybersecurity skills, either through a demonstrated record of teaching excellence, or through industrial experience. The successful candidate will also be involved in creating course content and materials with a focus on hands-on experiential and project-based learning. Strong written, oral and interpersonal skills are required in order to communicate effectively with students in person and online. The formal education and experience prerequisites may be waived at the university's discretion if the candidate can demonstrate to the satisfaction of the university an equivalent combination of education and experience specifically preparing the candidate for success in the position.
Interested applicants should submit their CV by applying as soon as possible at: https://njit.csod.com/ux/ats/careersite/1/home/requisition/3493?c=njit
Work environment and location:
The Computer Science department, part of the Ying Wu College of Computing, is the largest at NJIT, comprising one-tenth of the student population. It is also the largest computer science department among all research universities in the New York metropolitan area. Located in Northern New Jersey, within the greater New York Metropolitan area, NJIT is part of a vibrant ecosystem of research universities and corporate research centers.
Diversity is a core value of NJIT and we are committed to make diversity, equity and inclusion, part of everything we do.
Closing date for applications:
Contact: Reza Curtmola (reza.curtmola@njit.edu)
More information: https://njit.csod.com/ux/ats/careersite/1/home/requisition/3493?c=njit
Subspace Labs
Who We Are
Subspace Network is building a radically decentralized, next-generation blockchain which allows developers to easily run Web3 apps at Internet scale. Subspace is based on original research funded by the US National Science Foundation and planning to launch its Network later this year. Subspace Labs is an early-stage, venture-backed startup with a remote-first, globally distributed team. To learn more, visit our website and read the technical whitepaper.
We are seeking a Protocol Research Intern to join our rapidly growing team of Blockchain and Cryptocurrency enthusiasts and engineers. As a Research Intern you will be responsible for assisting in analyzing the security claims of the Subspace Network. Your goal is to work on proving these claims or suggesting improvement to the protocol as needed to support them.
Other Areas for Contribution: Research and review our solutions to some of the hardest problems in the blockchain space, as they relate to Nakamoto consensus, decentralized storage, decoupled execution, crypto-economic incentives, and the blockchain scalability trilemma; collaborate with our Research team to transform findings into peer-review quality specificaitons, publications, and presentations; work with our university partners, academic advisors, and third party engineering security partners on formal security analyses and audits.
Key Requirements: Currently enrolled in a graduate program in computer science, cryptography, or a related field, with the ability to dedicate at least 8 weeks to the internship Completed graduate level coursework in cryptography, distributed systems, peer-to-peer networking, or crypto-economic game theory; excellent written and verbal communication skills, and the ability to collaborate across our protocol and research teams; passion and curiosity for decentralized, peer-to-peer systems and Web3 technologies.
What We Offer: Competitive compensation and flexibility to work from anywhere in the world; a unique opportunity to shape the future of the Subspace Network and play a critical role in building the worlds most scalable blockchain.
Closing date for applications:
Contact: Sky McWilliams, Director of People
More information: https://jobs.lever.co/subspacelabs/3594920a-d99c-40c0-9ca3-66c7eaf639da?lever-origin=applied&lever-source%5B%5D=IACR