IACR News
Here you can see all recent updates to the IACR webpage. These updates are also available:
27 October 2023
Télécom Paris, Institut Polytechnique de Paris, France
- Design/analysis of symmetric cryptosystems
- Application of symmetric primitives in fully homomorphic encryption, zero-knowledge proof etc.
- Master program in Math, CS, or relevant fields
- Master degree in Math, CS, or relevant fields
- Strong mathematics background
- Strong ability in at least one programming language
- Understanding basic cryptanalysis methods is a plus
- Holding or finishing a Ph.D. degree in cryptography, IT security, or a related field
- Preference will be given to candidates with a strong publication record at IACR conferences or top security conferences
Closing date for applications:
Contact: Qingju Wang (qingju.wang@telecom-paris.fr)
University of Bristol, UK
These research-focused posts (advertised as "job number" ACAD107178) represent an exciting opportunity to join the Cryptography group at the University of Bristol (UoB), forming part of an Innovate UK funded project whose central focus is development of a RISC-V based micro-processor tailored to the needs of the aerospace industry. Work at UoB relates to cyber-security in general terms, and cryptography more specifically. More specifically still, the posts are aligned with research and engineering (or development) tasks that aim to enhance efficiency and security properties of cryptographic workloads as executed on the micro-processor; such tasks span elements of both software and hardware infrastructure, and demand consideration of both short- and long-term requirements. Given the project remit, a strong background and interest in at least one of the following research fields is therefore desirable:
- instruction set and micro-processor design and implementation (e.g., using HDL- and FPGA-based prototypes),
- cryptography, including lightweight (LWC) and post-quantum (PQC) constructions,
- cryptographic engineering, including high-assurance hardware or software implementation (e.g., formal specification of and verification with respect to security properties) and implementation (e.g., side-channel and fault induction) attacks,
- programming language and compiler design and implementation, ideally including the Jasmin and/or EasyCrypt tools.
Applicants with a purely academic background would ideally have a (completed or near completed) PhD in an appropriate discipline such as Computer Science. However, the project remit means that we view relevant industrial experience as extremely valuable: we therefore equally encourage applicants of this type. Successful applicants will be employed on a full-time, open-ended basis with funding available until 30/04/27; the appointments will be made at the Research Associate upto Research Fellow level depending on experience, implying a full-time starting salary of between £37,099 upto £48,350.
Closing date for applications:
Contact: Daniel Page (Daniel.Page@bristol.ac.uk)
More information: https://www.bristol.ac.uk/jobs/find/details/?jobId=326978
Beijing Institute of Mathematical Sciencesand Applications(BIMSA), DingLab; Beijing, China
A fully funded position on the DingLab in Cryptography and its applications at the Yanqi Lake Beijing Institute of Mathematical Sciences and Applications (BIMSA).
Ding LabThe Ding Lab in Public Key Cryptography will be led by Prof. Jintai Ding. It is an international open laboratory with English as the working language. Anyone who works in related areas including (but not restricted to) computational algebra, computational algebraic geometry, number theory, mathematical optimization, quantum algorithms, post-quantum cryptography, multi-party computation, zero-knowledge proof, fully homomorphic encryption, privacy-preserving algorithms, blockchain, high-performance computing, and algorithm implementations are welcome to apply.
Job RequirementsThe position requires you to have a doctorate or master's degree in Computer Science, Mathematics, Cryptography, or equivalent practical experience.
SalaryBIMSA offers internationally competitive salary packages and salary will be determined by the applicant's qualifications. Recent PhDs are especially encouraged to apply. A typical appointment for a postdoc of BIMSA is for two years, renewable for the third year with annual salary ranges from 300,000 RMB to 500,000 RMB depending on experience and qualifications.
BIMSAThe BIMSA is a Mathematics research institution co-sponsored by the Beijing Municipal Government and Tsinghua University, and the director of BIMSA is the renowned mathematician, Prof. Shing-Tung Yau. The BIMSA is located in the Huairou District of Beijing and is part of Beijing’s strategic plans to build world-class new-style research & development institutions and national innovation centers for science and technology. The BIMSA aims to develop fundamental scientific research and build a bridge between mathematics and industry applications.
Closing date for applications:
Contact: Prof. Jintai Ding, the dual-appointed Professor at the Yau Mathematical Sciences Center of Tsinghua University and the Beijing Institute of Mathematical Sciences and Applications.
João Diogo Duarte
Juan Garay, Aggelos Kiayias, Yu Shen
So far, the fastest way to achieve consensus in the proof-of-work (PoW)-based setting of Bitcoin, takes O(polylog $\kappa$) number of rounds, where $\kappa$ is the security parameter. We present the first protocol in this setting that requires expected-constant number of rounds. Further, we show how to apply securely sequential composition in order to yield a fast distributed ledger protocol that settles all transactions in expected-constant time. Our result is based on a novel instantiation of ``m-for-1 PoWs'' on parallel chains that facilitates our basic building block, Chain-King Consensus. The techniques we use, via parallel chains, to port classical protocol design elements (such as Phase-King Consensus, super-phase sequential composition and others) into the permissionless setting may be of independent interest.
Antonio Sanso
26 October 2023
Jaiden Fairoze, Sanjam Garg, Somesh Jha, Saeed Mahloujifar, Mohammad Mahmoody, Mingyuan Wang
Yu Song, Yu Long, Xian Xu, Dawn Gu
Orr Dunkelman, Shibam Ghosh, Nathan Keller, Gaetan Leurent, Avichai Marmor, Victor Mollimard
In this paper we show that the partial sums technique can be combined with an FFT-based technique, to get the best of the two worlds. Using our combined technique, we obtain an attack on 6-round AES with complexity of about $2^{46.4}$ additions. We fully implemented the attack experimentally, along with the partial sums attack and the Todo-Aoki attack, and confirmed that our attack improves the best known attack on 6-round AES by a factor of more than 32.
We expect that our technique can be used to significantly enhance numerous attacks that exploit the partial sums technique. To demonstrate this, we use our technique to improve the best known attack on 7-round Kuznyechik by a factor of more than 80, and to reduce the complexity of the best known attack on the full MISTY1 from $2^{69.5}$ to $2^{67}$.
Nilanjan Datta, Avijit Dutta, Eik List, Sougata Mandal
Abel C. H. Chen
Thai Duong, Jiahui Gao, Duong Hieu Phan, Ni Trieu
Pyrros Chaidos, Aggelos Kiayias, Leonid Reyzin, Anatoliy Zinovyev
We define an Approximate Lower Bound Argument, or ALBA, which allows the prover to do just that: to succinctly prove knowledge of a large number of elements satisfying a predicate (or, more generally, elements of a sufficient total weight when a predicate is generalized to a weight function). The argument is approximate because there is a small gap between what the prover actually knows and what the verifier is convinced the prover knows. This gap enables very efficient schemes.
We present noninteractive constructions of ALBA in the random oracle and uniform reference string models and show that our proof sizes are nearly optimal. We also show how our constructions can be made particularly communication-efficient when the evidence is distributed among multiple provers, which is of practical importance when ALBA is applied to a decentralized setting.
We demonstrate two very different applications of ALBAs: for large-scale decentralized signatures and for proving universal composability of succinct proofs.
Thomas Espitau, Alexandre Wallet, Yang Yu
As a by-product, we obtain novel, quasi-linear samplers for prime and smooth conductor (as $2^\ell 3^k$) cyclotomic rings, achieving essentially optimal Gaussian width. In a practice-oriented application, we showcase the impact of our work on hash-and-sign signatures over \textsc{ntru} lattices. In the best case, we can gain around 200 bytes (which corresponds to an improvement greater than 20\%) on the signature size. We also improve the new gadget-based constructions (Yu, Jia, Wang, Crypto 2023) and gain up to 110 bytes for the resulting signatures.
Lastly, we sprinkle our exposition with several new estimates for the smoothing parameter of lattices, stemming from our algorithmic constructions and by novel methods based on series reversion.
Jannis Leuther, Stefan Lucks
Claudia Bartoli, Ignacio Cascudo
In this paper, we introduce a universal construction of $\Sigma$-protocols designed to prove knowledge of preimages of group homomorphisms for any abelian finite group. In order to do this, we first establish a general construction of a $\Sigma$-protocol for $\mathfrak{R}$-module homomorphism given only a linear secret sharing scheme over the ring $\mathfrak{R}$, where zero knowledge and special soundness can be related to the privacy and reconstruction properties of the secret sharing scheme. Then, we introduce a new construction of 2-out-of-$n$ packed black-box secret sharing scheme capable of sharing $k$ elements of an arbitrary (abelian, finite) group where each share consists of $k+\log n-3$ group elements. From these two elements we obtain a generic ``batch'' $\Sigma$-protocol for proving knowledge of $k$ preimages of elements via the same group homomorphism, which communicates $k+\lambda-3$ elements of the group to achieve $2^{-\lambda}$ knowledge error.
For the case of class groups, we show that our $\Sigma$-protocol improves in several aspects on existing proofs for knowledge of discrete logarithm and other related statements that have been used in a number of works.
Finally, we extend our constructions from group homomorphisms to the case of ZK-ready functions, introduced by Cramer and Damg\aa rd in Crypto 09, which in particular include the case of proofs of knowledge of plaintext (and randomness) for some linearly homomorphic encryption schemes such as Joye-Libert encryption. However, in the case of Joye-Libert, we show an even better alternative, using Shamir secret sharing over Galois rings, which achieves $2^{-k}$ knowledge soundness by communicating $k$ ciphertexts to prove $k$ statements.
Ignacio Cascudo, Bernardo David
We introduce a PVSS scheme over class groups that achieves similar efficiency to state-of-the art schemes that only allow for reconstructing a function of the secret, while our scheme allows the reconstruction of the original secret. Our construction generalizes the DDH-based scheme of YOLO YOSO to operate over class groups, which poses technical challenges in adapting the necessary NIZKs in face of the unknown group order and the fact that efficient NIZKs of knowledge are not as simple to construct in this setting.
Building on our PVSS scheme's ability to recover the original secret, we propose two DKG protocols for discrete logarithm key pairs: a biasable 1-round protocol, which improves on the concrete communication/computational complexities of previous works; and a 2-round unbiasable protocol, which improves on the round complexity of previous works. We also add publicly verifiable resharing towards anonymous committees to our PVSS, so that it can be used to efficiently transfer state among committees in the YOSO setting. Together with a recent construction of MPC in the YOSO model based on class groups (Braun et al. CRYPTO'23), this results in the most efficient full realization (i.e without assuming receiver anonymous channels) of YOSO MPC based on the CDN framework with transparent setup.