IACR News
If you have a news item you wish to distribute, they should be sent to the communications secretary. See also the events database for conference announcements.
Here you can see all recent updates to the IACR webpage. These updates are also available:
02 December 2022
Aoxuan Li, Gabriele D’Angelo, Jacky Tang, Frank Fang, Baron Gong
We propose an auditable and affordable protocol for cross-chain and single-chain transactions. This protocol leverages zero-knowledge proofs to encrypt transactions and perform validation without disclosing sensitive users' data. To meet regulations, each auditor from an auditing committee will have an encrypted secret share of the transaction data. Auditors may view the private transaction data only if a majority of the committee agrees to decrypt the data. We employ a ZK-rollup scheme by processing multiple transactions in batches, which reduces private transaction costs to 90\% lower compared with solutions without ZK-rollup. We implemented the proposed scheme using Zokrates and Solidity and evaluated the protocol on the Ethereum test network, and the total one-to-one private transactions cost only 5 seconds. We also proved the security of the protocol utilizing the standard real/ideal world paradigm.
Hyunji Kim, Kyungbae Jang, Sejin Lim, Yeajun Kang, Wonwoong Kim, Hwajeong Seo
Shoichi Hirose, Kazuhiko Minematsu
Koksal Mus, Yarkın Doröz, M. Caner Tol, Kristi Rahman, Berk Sunar
Here we introduce Jolt, a novel attack targeting signature scheme implementations. Our attack exploits faulty signatures gained by injecting faults during signature generation. By using the signature verification primitive, we correct faulty signatures and, in the process deduce bits of the secret signing key. Compared to recent attacks that exploit single bit biases in the nonce that require $2^{45}$ signatures, our attack requires less than a thousand faulty signatures for a $256$-bit (EC)DSA. The performance improvement is due to the fact that our attack targets the secret signing key, which does not change across signing sessions. We show that the proposed attack also works on Schnorr and RSA signatures with minor modifications.
We demonstrate the viability of Jolt by running experiments targeting TLS handshakes in common cryptographic libraries such as WolfSSL, OpenSSL, Microsoft SymCrypt, LibreSSL, and Amazon s2n. On our target platform, the online phase takes less than 2 hours to recover $192$ bits of a $256$-bit ECDSA key, which is sufficient for full key recovery. We note that while RSA signatures are protected in popular cryptographic libraries, OpenSSL remains vulnerable to double fault injection. We have also reviewed their FIPS hardened versions which is slightly less efficient but still vulnerable to our attack. We found that (EC)DSA signatures remain largely unprotected against software-only faults, posing a threat to real-life deployments such as TLS, and potentially other security protocols such as SSH and IPSec. This highlights the need for a thorough review and implementation of faults checking in security protocol implementations.
Vasyl Ustimenko
30 November 2022
Jesús-Javier Chi-Domínguez
Kirill Vedenev, Yury Kosolapov
Joo Woo, Kwangsu Lee, Jong Hwan Park
Jonghyun Kim, Jong Hwan Park
In this work, we suggest a new NTRU-based key encapsulation mechanism (KEM), called NTRU+, which overcomes almost all existing drawbacks. NTRU+ is constructed based on two new generic transformations called $\mathsf{ACWC}_{2}$ and $\overline{\mathsf{FO}}^{\perp}$. $\mathsf{ACWC}_{2}$ is used for easily achieving a worst-case correctness error, and $\overline{\mathsf{FO}}^{\perp}$ (as a variant of the Fujisaki-Okamoto transform) is used for achieving chosen-ciphertext security without re-encryption. $\mathsf{ACWC}_{2}$ and $\overline{\mathsf{FO}}^{\perp}$ are all defined using a randomness-recovery algorithm and an encoding method. Especially, our simple encoding method, called $\mathsf{SOTP}$, allows us to sample a message from a natural bit-sting space with an arbitrary distribution. We provide four parameter sets for NTRU+ and give implementation results, using NTT-friendly rings over cyclotomic trinomials.
Jon-Lark Kim, Jihoon Hong, Terry Shue Chien Lau, YounJae Lim, Chik How Tan, Theo Fanuela Prabowo, Byung-Sun Won
Marta Bellés-Muñoz, Jorge Jiménez Urroz, Javier Silva
In this paper, we explore $2$-cycles composed of curves from families parameterized by polynomials, and show that such cycles do not exist unless a strong condition holds. As a consequence, we prove that no $2$-cycles can arise from the known families, except for those cycles already known. Additionally, we show some general properties about cycles, and provide a detailed computation on the density of pairing-friendly cycles among all cycles.
Han Wu, Guangwu Xu
Mashrukh Zayed, Adnan Anwar, Ziaur Rahman, Sk. Shezan Arefin, Rafiqul Islam
Yi Chen, Zhenzhen Bao, Yantian Shen, Hongbo Yu
This work provides an answer to this question by proposing a deep learning aided multi-stage key-recovery framework. To apply this key-recovery framework on large-state members of Speck, multiple neural distinguishers (NDs) are trained and carefully combined into groups. Employing the groups of NDs under the multi-stage key-recovery framework, practical attacks are designed and trialed. Experimental results show the effectiveness of the framework. The practical attacks are then extended into theoretical attacks that cover more rounds. To do that, multi-round classical differentials (CDs) are used together with the NDs. To find the CDs’ neutral bits to boost signals from the distinguishers, an efficient algorithm is proposed.
As a result, considerable improvement in terms of both time and data complexity of differential key-recovery attacks on round-reduced Speck with the largest, i.e., the 128-bit state, is obtained. Besides, efficient differential attacks are achieved on round-reduced Speck with 96-bit and 64-bit states. Since most real-world block ciphers have a state size of no less than 64 bits, this work paves the way for performing cryptanalysis using deep learning on more block ciphers. The code is available at https://github.com/AI-Lab-Y/NAAF.
Andreas Freitag
Microsoft Research, Redmond, WA
Please apply as soon as possible at https://careers.microsoft.com/us/en/job/1483268/Research-Intern-Privacy-and-Cryptography.
Closing date for applications:
Contact: Kim Laine
More information: https://careers.microsoft.com/us/en/job/1483268/Research-Intern-Privacy-and-Cryptography
NTT Research, Sunnyvale, CA, USA
Internships. Internships typically are for about 12 weeks during the summer. For the duration of their internship, interns will be matched with one of our research scientists as a mentor. Summer housing assistance is available. Interested individuals should have demonstrated strong mathematical ability and be enrolled in a PhD program with a focus on cryptography, computer security, or theoretical computer science.
Postoctoral research positions. Postdoctoral research positions are available with an initial duration of one year, and the possibility of extension to two years. Postdocs will be matched with a host from the lab, but are welcome to collaborate with any of our world-class scientists. Applicants should have or expect to have a PhD degree relating to cryptography, computer security, or theoretical computer science by summer 2023.
Fulltime Scientist. We are looking to hire Scientists in both foundational and applied cryptography to join our permanent team. For further information, please visit https://careers.ntt-research.com/cis
Closing date for applications: Dec 20, 2022.
Closing date for applications:
Contact: cis.careers@ntt-research.com
More information: https://careers.ntt-research.com/cis
Lund University, Department of Electrical and Information Technology
Closing date for applications:
Contact: Christian Gehrmann
More information: https://lu.varbi.com/what:job/jobID:569632/
Copper (www.copper.co)
Our award-winning custody application leverages the genius of multi-party computation (MPC) and can be configured to support cold, warm, and hot wallet solutions. Our culture is based on innovation, enthusiasm and above all else collaboration. Key Responsibilities:
Closing date for applications:
Contact: Alan Brophy (alan.brophy@copper.co)
More information: https://grnh.se/da97a862teu
The University of Manchester, Department of Computer Science
Closing date for applications:
Contact: Bernardo Magri (bernardo dot magri at manchester.ac.uk)