IACR News
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27 November 2023
Neil Thanawala, Hamid Nejatollahi, Nikil Dutt
ePrint ReportAhmad Khoureich Ka
ePrint ReportIn this paper, we propose a non-monotone CP-ABE scheme that has no restrictions on the size of attribute sets and policies, allows fast decryption and is adaptively secure under the CBDH-3 assumption. To achieve this, we approached the problem from a new angle, namely using a set membership relation for access structure. We have implemented our scheme using the Java Pairing-Based Cryptography Library (JPBC) and the source code is available on GitHub.
25 November 2023
University of Waterloo, Department of Combinatorics & Optimization; Waterloo, Canada
Job PostingThe Department of Combinatorics and Optimization in the Faculty of Mathematics at the University of Waterloo invites applications for three tenure-track faculty positions at the rank of Assistant Professor. Appointments at the level of Associate or Full Professor with tenure will be considered in special cases that substantially enhance the reputation of the department. Stellar candidates in the research areas of algebraic combinatorics, continuous optimization, cryptography, discrete optimization, and graph theory, who can greatly enhance the research and teaching profile of the department, are welcome to apply. Cryptography and optimization are the focus areas for these positions, and within optimization, continuous optimization is a priority area.
A Ph.D. degree and evidence of excellence in research and teaching are required. Successful applicants are expected to maintain an active program of research, to attract and supervise graduate students, and to participate in undergraduate and graduate teaching.
The salary range for the position is $105,000 to $155,000. Negotiations beyond this salary range will be considered for exceptionally qualified candidates. The anticipated start date is July 1, 2024. Interested individuals should apply using the MathJobs site (https://www.mathjobs.org/jobs/list/23241). Applications should include a curriculum vitae, research and teaching statements, and up to three reprints/preprints. In addition, at least three reference letters should be submitted.
The deadline for applications is December 4, 2023. Applications received by December 4, will be given full consideration. However, applications will continue to be reviewed until the position is filled.
Closing date for applications:
Contact: Chaitanya Swamy, Chair, Department of Combinatorics and Optimization
More information: https://www.mathjobs.org/jobs/list/23241
24 November 2023
Julian Loss, Jesper Buus Nielsen
ePrint ReportSahil Sharma
ePrint ReportKathrin Hövelmanns, Christian Majenz
ePrint ReportThe proof in [HHM22] involves a new correctness notion for the encryption scheme that is used to encapsulate the keys. This allows in principle for a smaller additive security related to decryption failures, but requires to analyze this new notion for the encryption scheme on which a concrete KEM at hand is based.
This note offers a trade-off between [HHM22] and its predecessors: it offers a bound for both rejection variants, being mostly based on [HHM22], but uses a more established correctness notion.
Julia Kastner, Ky Nguyen, Michael Reichle
ePrint ReportAlex Biryukov, Marius Lombard-Platet
ePrint ReportYuchao Chen, Tingting Guo, Lei Hu, Lina Shang, Shuping Mao, Peng Wang
ePrint ReportNishat Koti, Varsha Bhat Kukkala, Arpita Patra, Bhavish Raj Gopal
ePrint ReportXudong Zhu, Xuyang Song, Yi Deng
ePrint ReportIn this study, We proposed the first publicly verifiable non-uniform ZK zk-SNARK scheme in the BPK model maintaining comparable efficiency with its conventional counterpart, which can also be compatible with the well-known transformation proposed by Bitansky et al. in TCC 2013 to obtain an efficient designated-verifier zk-SNARK. We achieve this goal by only adding a constant number of elements into the CRS, and using an unconventional but natural method to transform Groth’s zkSNARK in EUROCRYPT 2016. In addition, we propose a new speed-up technique that provides a trade-off. Specifically, if a logarithmic number of elements are added into the CRS, according to different circuits, the CRS verification time in our construction could be approximately 9%-23% shorter than that in the conventional counterpart.
Hien Chu, Khue Do, Lucjan Hanzlik
ePrint ReportMarian Dietz, Stefano Tessaro
ePrint ReportThis problem was recently considered by Colombo et al. (USENIX '23), who proposed solutions secure under the assumption that the database is committed to honestly. Here, we close this gap, and present a solution that tolerates fully malicious servers that provide potentially malformed commitments. Our scheme has communication and client computational complexity $\mathcal{O}_{\lambda}(\sqrt{N})$, solely relies on the DDH assumption, and does not introduce heavy machinery (e.g., generic succinct proofs). Privacy with abort holds provided the server succeeds in correctly answering $\lambda$ validation queries, which, from its perspective, are computationally indistinguishable from regular PIR queries. In fact, server side, our scheme is exactly the DDH-based scheme by Colombo et al.
Gaëtan Leurent, Clara Pernot
ePrint ReportElette Boyle, Geoffroy Couteau, Pierre Meyer
ePrint ReportSignificant advances have been made affirmatively answering this question within the two-party setting, based on a variety of structures and hardness assumptions. In contrast, in the multi-party setting, only one general approach is known: using Fully Homomorphic Encryption (FHE). This remains the state of affairs even for just three parties, with two corruptions.
We present a framework for achieving secure sublinear-communication $(N+1)$-party computation, building from a particular form of Function Secret Sharing for only $N$ parties. In turn, we demonstrate implications to sublinear secure computation for various function classes in the 3-party and 5-party settings based on an assortment of assumptions not known to imply FHE.
Falko Strenzke
ePrint ReportFukang Liu, Abul Kalam, Santanu Sarkar, Willi Meier
ePrint ReportSrinath Setty, Justin Thaler
ePrint ReportCarlos Aguilar-Melchor, Victor Dyseryn, Philippe Gaborit
ePrint ReportWe study a candidate bootstrapping algorithm that requires no multiplication but additions and plaintext absorptions only. This latter operation is therefore very efficient in our scheme, whereas bootstrapping is usually the main reason which penalizes the performance of other fully homomorphic encryption schemes. However, the security reduction of our scheme restricts the number of independent ciphertexts that can be published. In particular, this prevents to securely evaluate the bootstrapping algorithm as the number of ciphertexts in the key switching material is too large.
Our scheme is nonetheless the first somewhat homomorphic encryption scheme based on random ideal codes and a first step towards full homomorphism. Random ideal codes give stronger security guarantees as opposed to existing constructions based on highly structured codes. We give concrete parameters for our scheme that shows that it achieves competitive sizes and performance, with a key size of 3.7 kB and a ciphertext size of 0.9 kB when a single multiplication is allowed.
Prabhanjan Ananth, Amit Behera
ePrint ReportNotably, we obtain the following new results assuming the existence of UPO:
- We show that any cryptographic functionality can be copy-protected as long as this functionality satisfies a notion of security, which we term as puncturable security. Prior feasibility results focused on copy-protecting specific cryptographic functionalities.
- We show that copy-protection exists for any class of evasive functions as long as the associated distribution satisfies a preimage-sampleability condition. Prior works demonstrated copy-protection for point functions, which follows as a special case of our result.
- We show that unclonable encryption exists in the plain model. Prior works demonstrated feasibility results in the quantum random oracle model.
We put forward a candidate construction of UPO and prove two notions of security, each based on the existence of (post-quantum) sub-exponentially secure indistinguishability obfuscation and one-way functions, the quantum hardness of learning with errors, and a new conjecture called simultaneous inner product conjecture.