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24 October 2022
Norwegian University of Science and Technology
Job PostingAfter six years of standardisation efforts to solicit, evaluate, and standardise one or more quantum-resistant public-key cryptographic algorithms, in the summer of 2022, the National Institute of Standards and Technology (NIST) from the USA has selected a portfolio of several algorithms. Those algorithms will be the new standards for Public-key Encryption and Key-establishment and for Digital Signatures.
We are now entering a phase where those post-quantum cryptographic standards must be efficiently implemented and deployed. The deployment phase faces challenges such as high-performance implementations, protocol updates with the post-quantum primitives, and levels of robustness and trustworthiness.
Duties of the position:
See https://www.jobbnorge.no/en/available-jobs/job/233227/associate-professor-in-post-quantum-cryptography for more details and how to apply.
Closing date for applications:
Contact: Professor Danilo Gligoroski (danilo.gligoroski@ntnu.no)
More information: https://www.jobbnorge.no/en/available-jobs/job/233227/associate-professor-in-post-quantum-cryptography
Florian Bourse, Malika Izabachène
ePrint ReportAnother desirable property of FHE called circuit privacy enables to preserve the privacy of the evaluation circuit, i.e. all the information on the bootstrapped ciphertext, including the computation that was performed to obtain it, is destroyed.
In this paper, we show how to directly build a circuit private FHE scheme from TFHE bootstrapping (Asiacrypt 2016). Our proof frame is inspired from the techniques used in Bourse etal (Crypto 2016), we provide a statistical analysis of the error growth during the bootstrapping procedure where we adapt discrete Gaussian lemmata over rings. We make use of a randomized decomposition for the homomorphic external product and introduce a public key encryption scheme with invariance properties on the ciphertexts distribution. As a proof of concept, we provide a C implementation of our sanitization strategy.
Lennart Braun, Ivan Damgård, Claudio Orlandi
ePrint ReportTo achieve this, we also design a new zero-knowledge protocol for proving multiplicative relations between encrypted values. As a result, the zero-knowledge proofs needed to get active security add only a constant factor overhead. Finally, we explain how to adapt our protocol for the so called "You-Only-Speak-Once" (YOSO) setting, which is a very promising recent approach for performing MPC over a blockchain.
Marloes Venema, Leon Botros
ePrint ReportIn this work, we present a new approach to achieving CCA-security as generically and efficiently as possible, by splitting the CCA-conversion in two steps. The predicate of the scheme is first extended in a certain way, which is then used to achieve CCA-security generically e.g., by combining it with a hash function. To facilitate the first step efficiently, we also propose a novel predicate-extension transformation for a large class of pairing-based PE---covered by the pair and the predicate encodings frameworks---which incurs only a small constant overhead for all algorithms. In particular, this yields the most efficient generic CCA-conversion for ciphertext-policy ABE.
Carsten Baum, James Hsin-yu Chiang, Bernardo David, Tore Kasper Frederiksen
ePrint ReportAgnese Gini, Pierrick Méaux
ePrint ReportIn this article, we introduce and study two new secondary constructions of WAPB functions. This new strategy allows us to bound the weightwise nonlinearities from those of the parent functions, enabling us to produce WAPB functions with high weightwise nonlinearities. As a practical application, we build several novel WAPB functions in up to $16$ variables by taking parent functions from two different known families. Moreover, combining these outputs, we also produce the $16$-variable WAPB function with the highest weightwise nonlinearities known so far.
Xiao Sui, Sisi Duan, Haibin Zhang
ePrint ReportXiaoling Yu, Yuntao Wang
ePrint ReportXiaojie Guo, Kang Yang, Xiao Wang, Wenhao Zhang, Xiang Xie, Jiang Zhang, Zheli Liu
ePrint Report• Halving the cost of COT and sVOLE. Our COT protocol introduces extra correlation to each level of a GGM tree used by the state-of-the-art COT protocol. As a result, it reduces both the number of AES calls and the communication by half. Extending this idea to sVOLE, we are able to achieve similar improvement with either halved computation or halved communication.
• Halving the cost of DPF and DCF. We propose improved two-party protocols for the distributed generation of DPF/DCF keys. Our tree structures behind these protocols lead to more efficient full-domain evaluation and halve the communication and the round complexity of the state-of-the-art DPF/DCF protocols.
All protocols are provably secure in the random-permutation model and can be accelerated based on fixed-key AES-NI. We also improve the state-of-the-art schemes of puncturable pseudorandom function (PPRF), DPF, and DCF, which are of independent interest in dealer-available scenarios.
Abhishek Jain, Zhengzhong Jin
ePrint ReportWe present a new framework aimed towards overcoming the input-length barrier. Our approach relies on short mathematical proofs of functional equivalence of circuits (and Turing machines) to avoid the brute-force ``input-by-input'' check employed in prior works. - We show how to obfuscate circuits that have efficient proofs of equivalence in Propositional Logic with a security loss independent of input length. - Next, we show how to obfuscate Turing machines with unbounded length inputs, whose functional equivalence can be proven in Cook's Theory $PV$. - Finally, we demonstrate applications of our results to succinct non-interactive arguments and witness encryption, and provide guidance on using our techniques for building new applications.
To realize our approach, we depart from prior work and develop a new gate-by-gate obfuscation template that preserves the topology of the input circuit.
Jiahui Liu, Qipeng Liu, Luowen Qian, Mark Zhandry
ePrint Report(*) The feasibility of copy-protecting all watermarkable functionalities is an open question raised by Aaronson et al. (CRYPTO' 21). In the literature, watermarking decryption, digital signature schemes and PRFs have been extensively studied. For the first time, we show that digital signature schemes can be copy-protected. Together with the previous work on copy-protection of decryption and PRFs by Coladangelo et al. (CRYPTO' 21), it suggests that many watermarkable functionalities can be copy-protected, partially answering the above open question by Aaronson et al. (*) We make all the above schemes (copy-protection of decryption, digital signatures, and PRFs) k bounded collusion resistant for any polynomial k, giving the first bounded collusion resistant copy-protection for various functionalities in the plain model.
Xuechao Wang, Peiyao Sheng, Sreeram Kannan, Kartik Nayak, Pramod Viswanath
ePrint ReportKyungbae Jang, Anubhab Baksi, Hyunji Kim, Hwajeong Seo, Anupam Chattopadhyay
ePrint ReportThe SPECK family received two quantum analysis till date (Jang et al., Applied Sciences, 2020; Anand et al., Indocrypt, 2020). We revisit these two works, and present improved benchmarks SPECK (all 10 variants). Our implementations incur lower full depth compared to the previous works.
On the other hand, the quantum circuit of LowMC was explored earlier in Jaques et al.'s Eurocrypt 2020 paper. However, there is an already known bug in their paper, which we patch. On top of that, we present two versions of LowMC (on L1, L3 and L5 variants) in quantum, both of which incur significantly less full depth than the bug-fixed implementation.
Esra Günsay, Oğuz Yayla
ePrint ReportCarlos Aguilar-Melchor, Jean-Christophe Deneuville, Arnaud Dion, James Howe, Romain Malmain, Vincent Migliore, Mamuri Nawan, Kashif Nawaz
ePrint ReportDavid W. Kravitz, Mollie Z. Halverson
ePrint ReportSunoo Park, Nicholas Spooner
ePrint ReportIsmail Afia, Riham AlTawy
ePrint ReportShravan Srinivasan, Julian Loss, Giulio Malavolta, Kartik Nayak, Charalampos Papamanthou, Sri AravindaKrishnan Thyagarajan
ePrint ReportIn this work, we demonstrate the feasibility and usefulness of a TLP that overcomes all of the above limitations. Our construction is based on indistinguishable obfuscation and shows that there are no fundamental barriers in achieving such a TLP construction. As a main application of our TLP, we show how to improve the resilience of consensus protocols toward network-level adversaries in the following two settings: (1) We show a generic compiler that boosts the resilience of a Byzantine broadcast protocol $\Pi$ as follows: if $\Pi$ is secure against $t
Conor McMenamin, Vanesa Daza, Bruno Mazorra
ePrint ReportIn this paper, we present Diamond, an automated market making protocol that aligns the incentives of liquidity providers and block producers in the protocol-level retention of LVR. In Diamond, block producers effectively auction the right to capture any arbitrage that exists between the external market price of a Diamond pool, and the price of the pool itself. The proceeds of these auctions are shared by the Diamond pool and block producer in a way that is proven to remain incentive compatible for the block producer. Given the participation of competing arbitrageurs, LVR is effectively prevented in Diamond. We formally prove this result, and detail an implementation of Diamond. We also provide comparative simulations of Diamond to relevant benchmarks, further evidencing the LVR-protection capabilities of Diamond. With this new protection, passive liquidity provision on blockchains becomes rationally viable, beckoning a new age for decentralized finance.