International Association
for Cryptologic Research

Event date: 29 June to 30 June 2023
Submission deadline: 7 February 2023
Notification: 14 March 2023

Event date: 29 August to 1 September 2023
Submission deadline: 9 March 2022
Notification: 23 May 2022

A distributed point function (DPF) (Gilboa-Ishai, Eurocrypt 2014) is a cryptographic primitive that enables compressed additive secret-sharing of a secret weight-1 vector across two or more servers. DPFs support a wide range of cryptographic applications, including efficient private information retrieval, secure aggregation, and more. Up to now, the study of DPFs was restricted to the computational security setting, relying on one-way functions. This assumption is necessary in the case of a dishonest majority.

We present the first statistically private 3-server DPF for domain size $N$ with subpolynomial key size $N^{o(1)}$. We also present a similar perfectly private 4-server DPF. Our constructions offer benefits over their computationally secure counterparts, beyond the superior security guarantee, including better computational complexity and better protocols for distributed key generation, all while having comparable communication complexity for moderate-sized parameters.

This paper describes a formalization of the specification and the algorithm of the cryptographic scheme CRYSTALS-KYBER as well as the verification of its (1 − δ)-correctness proof. During the formalization, a problem in the correctness proof was uncovered. In order to amend this issue, a necessary property on the modulus parameter of the CRYSTALS-KYBER algorithm was introduced. This property is already implicitly fulfilled by the structure of the modulus prime used in the number theoretic transform (NTT). The NTT and its convolution theorem in the case of CRYSTALS-KYBER was formalized as well. The formalization was realized in the theorem prover Isabelle.

We are applying Fermat’s factorization algorithm to sets of public RSA keys. Fermat’s factorization allows efficiently calculating the prime factors of a composite number if the difference between the two primes is small. Knowledge of the prime factors of an RSA public key allows efficiently calculating the private key. A flawed RSA key generation function that produces close primes can therefore be attacked with Fermat’s factorization. We discovered a small number of vulnerable devices that generate such flawed RSA keys in the wild. These affect devices from two printer vendors - Canon and Fuji Xerox. Both use an underlying cryptographic module by Rambus.

In this paper, we investigate the security of several recent MAC constructions with provable security beyond the birthday bound (called BBB MACs) in the quantum setting. On the one hand, we give periodic functions corresponding to targeted MACs (including PMACX, PMAC with parity, HPxHP, and HPxNP), and we can recover secret states using Simon algorithm, leading to forgery attacks with complexity O(n). This implies our results realize an exponential speedup compared with the classical algorithm. Note that our attacks can even break some optimally secure MACs, such as mPMAC+-f, mPMAC+-p1, mPMAC+-p2, mLightMAC+-f, etc. On the other hand, we construct new hidden periodic functions based on SUM-ECBC-like MACs: SUM-ECBC, PolyMAC, GCM-SIV2, and 2K-ECBC−Plus, where periods reveal the information of the secret key. Then, by applying Grover-meets-Simon algorithm to specially constructed functions, we can recover full keys with O(2^(n/2)n) or O(2^(m/2)n) quantum queries, where n is the message block size and m is the length of the key. Considering the previous best quantum attack, our key-recovery attacks achieve a quadratic speedup.

Functional Encryption (FE) is a modern cryptographic technique that allows users to learn only a specific function of the encrypted data and nothing else about its actual content. While the first notions of security in FE revolved around the privacy of the encrypted data, more recent approaches also consider the privacy of the computed function. While in the public key setting, only a limited level of function-privacy can be achieved, in the private-key setting privacy potential is significantly larger. However, this potential is still limited by the lack of rich function families. For this work, we started by identifying the limitations of the current state-of-the-art approaches which, in its turn, allowed us to consider a new threat model for FE schemes. To the best of our knowledge, we here present the first attempt to quantify the leakage during the execution of an FE scheme. By leveraging the functionality offered by Trusted Execution Environments, we propose a construction that given any message-private functional encryption scheme yields a function-private one. Finally, we argue in favour of our construction's applicability on constrained devices by showing that it has low storage and computation costs.

The Feistel construction is one of the most studied ways of building block ciphers. Several generalizations were proposed in the literature, leading to the Generalized Feistel Network (GFN) construction, in which the round function operates on each pair of blocks in parallel until all branches are permuted. At FSE'10, Suzaki and Minematsu studied the diffusion of such construction, raising the question of how many rounds are required so that each block of the ciphertext depends on all blocks of the plaintext. Exhausting all possible permutations up to 16 blocks, they observed that there were always optimal permutations mapping even-number input blocks to odd-number output blocks and vice versa. Recently, both Cauchois et al. and Derbez et al. proposed new algorithms to build optimal even-odd permutations for up to 36 blocks. In this paper, we present a new algorithm based on iterative path building to search for optimal Feistel permutation. This algorithm is much faster in exhausting optimal non-even-odd permutations than all the previous approaches. Our first result is a computational proof that no non-even-odd permutation reaches a better diffusion round than optimal even-odd permutations up to 32 blocks. Furthermore, it is well known that permutations with an optimal diffusion round do not always lead to optimal permutations against differential cryptanalysis. We investigate several new criteria to build permutations leading to more secure GFN.

Embedded systems are a cornerstone of the ongoing digitization of our society, ranging from expanding markets around IoT and smart-X devices over to sensors in autonomous driving, medical equipment or critical infrastructures. Since a vast amount of embedded systems are safety-critical (e.g., due to their operation site), security is a necessity for their operation. However, unlike mobile, desktop, and server systems, where adversaries typically only act have remote access, embedded systems typically face attackers with physical access. Thus embedded system require an additional set of defense techniques, preferably leveraging hardware acceleration to minimize the impact on their stringent operation constraints. Over the last decade numerous defenses have been explored, however, they have often been analyzed in isolation.

In this work, we first systematically analyze the state of the art in defenses for both software exploitation and fault attacks on embedded systems. We then carefully design a holistic instruction set extension to augment the RISC-V instruction set architecture with instructions to deter against the threats analyzed in this work. Moreover we implement our design using the gem5 simulator system and a binary translation approach to arm software with our instruction set extension. Finally, we evaluate performance overhead on the MiBench2 benchmark suite. Our evaluation demonstrates a ROM overhead increase of 20% to defeat the aforementioned attacks.

Deep learning techniques have been widely used in side-channel analysis (SCA) in recent years and shown better performance compared with traditional methods. However, there has been little research dealing with deep learning techniques in fault analysis to date. This article undertakes the first study to introduce deep learning into fault analysis. We investigate the application of multi-layer perceptron (MLP) and convolutional neural network (CNN) in persistent fault analysis (PFA) and propose deep learning-based persistent fault analysis (DLPFA). DLPFA is first applied to advanced encryption standard (AES) to verify its availability. Then, to push the study further, we extend DLPFA to PRESENT, which is a lightweight substitution–permutation network (SPN)-based block cipher. The experimental results show that DLPFA can handle random faults and provides outstanding performance with a suitable selection of hyper-parameters.

It is known that the Scholz conjecture on addition chains is true for all integers n with ℓ(2n) = ℓ(n) + 1. There exists infinitely many integers with ℓ(2n) ≤ ℓ(n) and we don’t know if the conjecture still holds for them. The conjecture is also proven to hold for integers n with v(n) ≤ 5 and for infinitely many integers with v(n) = 6. There is no specific results on integers with v(n) = 7. In [14], an infinite list of integers satisfying ℓ(n) = ℓ(2n) and v(n) = 7 is given by Thurber. In this paper, we prove that the conjecture holds for all of them.

Hyperparameter tuning represents one of the main challenges in deep learning-based profiling side-channel analysis. For each different side-channel dataset, the typical procedure to find a profiling model is applying hyperparameter tuning from scratch. The main reason is that side-channel measurements from various targets contain different underlying leakage distributions. Consequently, the same profiling model hyperparameters are usually not equally efficient for other targets. This paper considers autoencoders for dimensionality reduction to verify if encoded datasets from different targets enable the portability of profiling models and architectures. Successful portability reduces the hyperparameter tuning efforts as profiling model tuning is eliminated for the new dataset, and tuning autoencoders is simpler. We first search for the best autoencoder for each dataset and the best profiling model when the encoded dataset becomes the training set. Our results show no significant difference in tuning efforts using original and encoded traces, meaning that encoded data reliably represents the original data. Next, we verify how portable is the best profiling model among different datasets. Our results show that tuning autoencoders enables and improves portability while reducing the effort in hyperparameter search for profiling models. Lastly, we present a transfer learning case where dimensionality reduction might be necessary if the model is tuned for a dataset with fewer features than the new dataset. In this case, tuning of the profiling model is eliminated and training time reduced.

The Department of Computer Science (CS) and the Department of Mathematics (Math) at the University of Central Florida (UCF) are seeking three full-time, 9-month faculty positions at the rank of assistant professor (tenure-earning), associate professor or professor (tenured) in the area of cyber security and privacy, with concentrations in one of the areas described below. The anticipated start date is August 8, 2023. • Area A (Math): Cryptography, applied cryptography, and intersection of algorithm and cryptography (e.g., quantum cryptography, post-quantum crypto, etc.). One faculty position is anticipated for this area. • Area B (Computer Science): Cloud, Edge, and IoT security (e.g., serverless computing, container security, etc.), system software, software supply chain security, and the security of Cyber Physical System, etc. Two faculty positions are anticipated for this area. These positions will be expected to strengthen both the tenure home department (Math or CS, as applicable), as well as the Cyber Security and Privacy Cluster and may include a combination of secondary joint appointments. The ideal candidates will be in the rank of assistant professor, but exceptional candidates at the rank of associate professor or professor will be considered. The ideal candidates will have a strong background in the areas listed.

Closing date for applications:

Contact: Questions regarding this search may be directed to Dr. Yan Solihin (yan.solihin@ucf.edu) or Dr. Paul Gazzillo (paul.gazzillo@ucf.edu).

More information: https://ucf.wd1.myworkdayjobs.com/careers/job/Orlando-FL-Main-Campus/Assistant-Professor--Associate-Professor--or-Professor--Cyber-Security-and-Privacy-Areas--Computer-Science-or-Mathematics-_R103069

The department of Mathematics and Computer Science at TU Eindhoven has a postdoc vacancy for work on quantum cryptography.

The research will focus on
* quantum cryptography beyond QKD, e.g. key recycling, unclonable encryption, unclonable credentials, quantum PUFs and similar schemes.
* theory related to the Quantum Communication testbed under development in Eindhoven.

The research takes place in the EIPSI institute, which is a collaboration between the Security group and the Coding and Cryptology group.
This position is part of a large, long term, well-funded national program on quantum technologies (Quantum Delta NL). One of the three development lines (Catalyst-2, or CAT2) is fully dedicated to Quantum Key Distribution, Communication and Quantum internet.

Closing date for applications:

Contact: Boris Skoric (b dot lastname at tue dot nl)

More information: https://jobs.tue.nl/en/vacancy/postdoc-quantum-protocols-970990.html

As our Director of Research & Development, you have full ownership of the vision, architecture, and deployment of our research across the innovative products at Horizen Labs. You will work closely with our researchers and engineers being the critical bridge between both areas. As a leader of a cutting-edge team, you will be a champion of translating R&D into meaningful products that will change the world. In collaboration with engineering leadership and our product managers, you will shape the technical direction of the entire company, leveraging our research in applied cryptography across various landscapes, including the privacy space, blockchain scalability, and ground-breaking security solutions. You are also passionate about coaching and mentoring your team members to help them grow technically, enhance their ability to get things done, and guide them toward their career goals.

Requirements

• Spearhead the design, prototyping, and rollout of PoCs (Proof of Concepts) that focuses on the market’s needs and brings true innovation to the greater research community;
• Co-create both near-term and long term roadmaps with Engineering and Product leadership to bring ideas from academic papers to live production-ready systems;
• Be responsible for our cryptographic team, serving them with empathy, humility, and passion to deliver ground-breaking products to the world;
• Promote a culture of innovation and collaboration both within our internal team and our broader network of researchers, advisors, and partners;
• Facilitate conversations and decisions among senior leaders to identify where the business needs to be next and craft a path to get us there;
• Take a proactive role in aligning organizations and influencing the overall technical direction of a company;
• Collaborate with other industry-leading luminaries, from our investors (Digital Currencies Group, Kenetic Capital, Liberty City Ventures, Sound Ventures), world-class blockchain partner, and devoted security experts (NCC, Halborn).

  Closing date for applications:

  Contact:

  Apply to: https://horizenlabs.io/careers/job/?gh_jid=4759378004

  More information: https://horizenlabs.io/careers/job/?gh_jid=4759378004

A postdoctoral position and a PhD position are open in the faculty of engineering at Bar-Ilan University, hosted by Prof. Carmit Hazay and starting in fall 2023.

The positions involve performing theoretical and practical research in cryptography and secure computation.

This project is in collaboration with the Technology Innovation Institute (TII) and participants will be offered several all-expenses-paid visits to TII.

The postdoctoral position is offered for 1 year and can be extended by an additional year contingent upon funding and satisfactory performance.

The PhD position spans an entire course of a PhD degree, with an expected duration of 4 years.

Applicants should have a general background in secure computation and cryptography. Candidates are expected to be highly motivated and mathematically capable.

Applications should include (1) a CV including a list of publications, (2) a short research statement, (3) names and contact information of 2-3 potential references.

Closing date for applications:

Contact: Applications should be emailed to carmit.hazay@biu.ac.il

Optimizing the quantum circuit for implementing Advanced Encryption Standard (AES) is crucial for estimating the necessary resources in attacking AES by Grover algorithm. Previous studies have reduced the number of qubits required for the quantum circuits of AES-128/-192/-256 from 984/1112/1336 to 270/334/398, which is close to the optimal value of 256/320/384. It becomes a challenging task to further optimize them. Aiming at this task, we find a method about how the quantum circuit of AES S-box can be designed with the help of automation tool LIGHTER-R. Particularly, the multiplicative inversion in F_2^8, which is the main part of S-box, is converted into the multiplicative inversion (and multiplication) in F_2^4, then the latter can be implemented by LIGHTER-R because its search space is small enough. By this method, we construct the quantum circuits of S-box for mapping |a>|0> to |a>|S(a)> and |a>|b> to |a>|b+S(a)> with 20 qubits instead of 22 in the previous studies. Besides, we introduce new techniques to reduce the number of qubits required by the S-box circuit for mapping |a> to |S(a)>from 22 in the previous studies to 16. Accordingly, we synthesize the quantum circuits of AES-128/-192/-256 with 264/328/392 qubits, which implies a new record.

We consider actions of a group or a semigroup on a set, which generalize the setup of discrete logarithm based cryptosystems. Such cryptographic group actions have gained increasing attention recently in the context of isogeny-based cryptography. We introduce generic algorithms for the semigroup action problem and discuss lower and upper bounds. Also, we investigate Pohlig-Hellman type attacks in a general sense. In particular, we consider reductions provided by non-invertible elements in a semigroup, and we deal with subgroups in the case of group actions.

The learning with errors (LWE) assumption is a powerful tool for building encryption schemes with useful properties, such as plausible resistance to quantum computers, or support for homomorphic computations. Despite this, essentially the only method of achieving threshold decryption in schemes based on LWE requires a modulus that is superpolynomial in the security parameter, leading to a large overhead in ciphertext sizes and computation time.

In this work, we propose a (fully homomorphic) encryption scheme that supports a simple $t$-out-of-$n$ threshold decryption protocol while allowing for a polynomial modulus. The main idea is to use the Rényi divergence (as opposed to the statistical distance as in previous works) as a measure of distribution closeness. This comes with some technical obstacles, due to the difficulty of using the Rényi divergence in decisional security notions such as standard semantic security. We overcome this by constructing a threshold scheme with a weaker notion of one-way security and then showing how to transform any one-way threshold scheme into one guaranteeing semantic security.

Non-interactive zero-knowledge (NIZK) proof systems are often constructed based on cryptographic assumptions. In this paper, we propose the first unconditionally secure NIZK system in the AC0-fine-grained setting. More precisely, our NIZK system has perfect soundness for all adversaries and unconditional zero-knowledge for AC0 adversaries, namely, an AC0 adversary can only break the zero-knowledge property with negligible probability unconditionally. At the core of our construction is an OR-proof system for satisfiability of 1 out of polynomial many statements.