IACR News
Here you can see all recent updates to the IACR webpage. These updates are also available:
08 January 2019
Chunning Zhou, Wentao Zhang, Tianyou Ding, Zejun Xiang
ePrint ReportYunhua Wen, Shengli Liu, Dawu Gu
ePrint ReportSai Krishna Deepak Maram, Fan Zhang, Lun Wang, Andrew Low, Yupeng Zhang, Ari Juels, Dawn Song
ePrint ReportCHURP includes several technical innovations: An efficient new proactivization scheme of independent interest, a technique (using asymmetric bivariate polynomials) for efficiently changing secret-sharing thresholds, and a hedge against setup failures in an efficient polynomial commitment scheme. We also introduce a general new technique for inexpensive off-chain communication across the peer-to-peer networks of permissionless blockchains.
We formally prove the security of CHURP, report on an implementation, and present performance measurements.
Yevgeniy Dodis, Paul Grubbs, Thomas Ristenpart, Joanne Woodage
ePrint ReportThomas Pornin, Thomas Prest
ePrint ReportA few lattice-based cryptographic schemes entail, generally during the key generation, solving the NTRU equation: $$ f G - g F = q \mod x^n + 1 $$ Here $f$ and $g$ are fixed, the goal is to compute solutions $F$ and $G$ to the equation, and all the polynomials are in $\mathbb{Z}[x]/(x^n + 1)$. The existing methods for solving this equation are quite cumbersome: their time and space complexities are at least cubic and quadratic in the dimension $n$, and for typical parameters they therefore require several megabytes of RAM and take more than a second on a typical laptop, precluding onboard key generation in embedded systems such as smart cards.
In this work, we present two new algorithms for solving the NTRU equation. Both algorithms make a repeated use of the field norm in tower of fields; it allows them to be faster and more compact than existing algorithms by factors $\tilde O(n)$. For lattice-based schemes considered in practice, this reduces both the computation time and RAM usage by factors at least 100, making key pair generation within range of smart card abilities.
Gaurav Panwar, Satyajayant Misra, Roopa Vishwanathan
ePrint ReportChanghai Ou, Siew-Kei Lam
ePrint ReportA Proof of the Beierle-Kranz-Leander's Conjecture related to Lightweight Multiplication in $F_{2^n}$
Sihem Mesnager, Kwang Ho Kim, Dujin Jo, Junyop Choe, Munhyon Han, Dok Nam Lee
ePrint ReportIn CRYPTO 2016, Beierle, Kranz and Leander have considered lightweight multiplication in ${F}_{2^n}$. Specifically, they have considered the fundamental question of optimizing finite field multiplications with one fixed element and investigated which field representation, that is which choice of basis, allows for an optimal implementation. They have left open a conjecture related to two XOR-count. Using the theory of linear algebra, we prove in the present paper that their conjecture is correct. Consequently, this proved conjecture can be used as a reference for further developing and implementing cryptography algorithms in lightweight devices.
Paul Grubbs, Marie-Sarah Lacharité, Brice Minaud, Kenneth G. Paterson
ePrint ReportAs an introduction to this viewpoint, we first present a general reduction from reconstruction with known queries to PAC learning. Then, we directly address the problem of $\epsilon$-approximate database reconstruction ($\epsilon$-ADR) from range query leakage, giving attacks whose query cost scales only with the relative error $\epsilon$, and is independent of the size of the database, or the number $N$ of possible values of data items. This already goes significantly beyond the state of the art for such attacks, as represented by Kellaris et al. (ACM CCS 2016) and Lacharit\'{e} et al. (IEEE S&P 2018).
We also study the new problem of $\epsilon$-approximate order reconstruction ($\epsilon$-AOR), where the adversary is tasked with reconstructing the order of records, except for records whose values are approximately equal. We show that as few as ${\mathcal{O}}(\epsilon^{-1} \log \epsilon^{-1})$ uniformly random range queries suffice. Our analysis relies on an application of learning theory to PQ-trees, special data structures tuned to compactly record certain ordering constraints.
We then show that when an auxiliary distribution is available, $\epsilon$-AOR can be enhanced to achieve $\epsilon$-ADR; using real data, we show that devastatingly small numbers of queries are needed to attain very accurate database reconstruction.
Finally, we generalize from ranges to consider what learning theory tells us about the impact of access pattern leakage for other classes of queries, focusing on prefix and suffix queries. We illustrate this with both concrete attacks for prefix queries and with a general lower bound for all query classes.
Rodrigo Abarzúa, Claudio Valencia, Julio López
ePrint ReportQian Guo, Thomas Johansson, Erik Mårtensson, Paul Stankovski Wagner
ePrint ReportJingyu Pan, Shivam Bhasin, Fan Zhang, Kui Ren
ePrint ReportMatthias Hamann, Matthias Krause
ePrint ReportIn the last years, a new line of research looking for alternative stream cipher constructions guaranteeing a higher TMD-TO resistance with smaller inner state lengths has emerged. So far, this has led to three generic constructions: the LIZARD construction, having a provable TMD-TO resistance of $2\cdot \mathit{SL}/3$; the Continuous-Key-Use construction, underlying the stream cipher proposals Sprout, Plantlet, and Fruit; and the Continuous-IV-Use construction, very recently proposed by Hamann, Krause, and Meier. Meanwhile, it could be shown that the Continuous-Key-Use construction is vulnerable against certain nontrivial distinguishing attacks.
In this paper, we present a formal framework for proving security lower bounds on the resistance of generic stream cipher constructions against TMD-TO attacks and analyze two of the constructions mentioned above. First, we derive a tight security lower bound of approximately $\min\{\mathit{KL},\mathit{SL}/2\}$ on the resistance of the Large-State-Small-Key construction. This shows that the feature $\mathit{KL}\le \mathit{SL}/2$ does not open the door for new nontrivial TMD-TO attacks against Trivium and Grain v1 which are more dangerous than the known ones. Second, we prove a maximal security bound on the TMD-TO resistance of the Continuous-IV-Use construction, which shows that designing concrete instantiations of ultra-lightweight Continuous-IV-Use stream ciphers is a hopeful direction of future research.
Antonio Marcedone, Rafael Pass, abhi shelat
ePrint ReportLilas Alrahis, Muhammad Yasin, Hani Saleh, Baker Mohammad, Mahmoud Al-Qutayri, Ozgur Sinanoglu
ePrint ReportGuillaume Dabosville, Houssem Maghrebi, Alexis Lhuillery, Julien Bringer, Thanh-Ha Le
ePrint ReportYuntao Liu, Yang Xie, Abhishek Charkraborty, Ankur Srivastava
ePrint ReportJianye Huang, Qiong Huang
ePrint ReportTo address this issue, Ono et al. introduced a new security model of group signature, which captures randomness exposure attacks. They proved that their proposed construction satisfies the security require-ments of group signature scheme. Nevertheless, their scheme is only provably secure against randomness exposure and supposes the secret keys remains leakage-free. In this work, we focus on the security model of leakage-resilient group signature based on bounded leakage setting and propose three new black-box constructions of leakage-resilient group signature secure under the proposed security models.
NUS-SingTel Cyber Security R&D Lab
Job Posting“NUS-Singtel Cyber Security R&D Lab” (http://nus-singtel.nus.edu.sg/) is a 5 years joint project with about SGD 43 mil (approximately USD 31 mil) of funds contributed by Singapore Telecommunications Limited (SingTel), National University of Singapore (NUS), and National Research Foundation (NRF) of Singapore. The R&D Lab will conduct research in four broad areas of cyber security having strategic relevance to Singtel’s business: (1) Predictive Security Analytics; (2) Network, Data and Cloud Security; (3) Internet-of-Things and Industrial Control Systems; (4) Future-Ready Cyber Security Systems.
NUS-SingTel Lab currently has one research fellow position with competitive pay. It is available to (fresh) PhD graduates in computer science/engineering from Singapore or overseas.
The Research Fellow will be responsible for working closely with the Principal Investigator and lab members on a new 3-year research project which just started in June 2018. He/she should possess experience or interest in at least some of the following research areas:
• Key management, Authentication, Authorization and Access control
• Trusted computing (e.g. TPM, Intel SGX)
• Post-quantum cryptography
Job requirements:
• A PhD degree in a relevant area (Computer Science/Engineer, mathematics, etc);
• Good publication record in cyber security and crypto area
• Publication in Rank 1 Cyber Security or Crypto Conference, or AsiaCrypt, ESORICS, ACSAC, TCC, Euro S&P, etc;
• Good communication skills, self-motivated and good team players;
• Some experience in programming is a plus;
• Willing to perform practical research which may eventually lead to products
To apply for the above position, please send a copy of your recent CV to \"comxj at nus.edu.sg\" with an email subject “Application for RF”.
Closing date for applications: 1 June 2019
Contact: Dr Xu,
comxj at nus.edu.sg
More information: https://www.nus-singtel.nus.edu.sg/
Singapore University of Technology and Design (SUTD), Singapore
Job PostingI am looking for PhD interns with interest in cyber-physical system security (IoT, power grid, water, transportation, and autonomous vehicle etc.). The attachment will be at least 3 months. Allowance will be provided for local expenses.
Interested candidates please send your CV with a research statement to Prof. Jianying Zhou. Only short-listed candidates will be contacted for interview.
Closing date for applications: 31 March 2019
Contact: Prof. Jianying Zhou
More information: http://jianying.space/