IACR News
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24 November 2023
Prabhanjan Ananth, Amit Behera
Notably, 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.
Andersson Calle Viera, Alexandre Berzati, Karine Heydemann
Mirza Ahad Baig, Suvradip Chakraborty, Stefan Dziembowski, Małgorzata Gałązka, Tomasz Lizurej, Krzysztof Pietrzak
Xiangfu Song, Dong Yin, Jianli Bai, Changyu Dong, Ee-Chien Chang
Dan Boneh, Aditi Partap, Brent Waters
Daniel Hugenroth, Alberto Sonnino, Sam Cutler, Alastair R. Beresford
Jamal Mosakheil, Kan Yang
Daniel Espinoza Figueroa
Arup Mondal, Priyam Panda, Shivam Agarwal, Abdelrahaman Aly, Debayan Gupta
Jung Hee Cheon, Wonhee Cho, Jaehyung Kim, Damien Stehlé
We propose a novel method, called $\mathsf{mult}^2$, to perform ciphertext multiplication in the CKKS scheme with lower modulus consumption. $\mathsf{mult}^2$ relies an a new decomposition of a ciphertext into a pair of ciphertexts that homomorphically performs a weak form of Euclidean division. It multiplies two ciphertexts in decomposed formats with homomorphic double precision multiplication, and its result approximately decrypts to the same value as does the ordinary CKKS multiplication. $\mathsf{mult}^2$ can perform homomorphic multiplication by consuming almost half of the modulus.
We extend it to $\mathsf{mult}^t$ for any $t\geq 2$, which relies on the decomposition of a ciphertext into $t$ components. All other CKKS operations can be equally performed on pair/tuple formats, leading to the double-CKKS (resp. tuple-CKKS) scheme enabling homomorphic double (resp. multiple) precision arithmetic.
As a result, when the ciphertext modulus and dimension are fixed, the proposed algorithms enable the evaluation of deeper circuits without bootstrapping, or allow to reduce the number of bootstrappings required for the evaluation of the same circuits. Furthermore, they can be used to increase the precision without increasing the parameters. For example, $\mathsf{mult}^2$ enables 8 sequential multiplications with 100 bit scaling factor with a ciphertext modulus of only 680 bits, which is impossible with the ordinary CKKS multiplication algorithm.
23 November 2023
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Submission deadline: 15 February 2024
Notification: 15 April 2024
Vodice, Croatia, 3 June - 7 June 2024
Submission deadline: 15 January 2024
Notification: 30 January 2024
Institute for Quantum Computing, University of Waterloo
Closing date for applications:
Contact: Dr Sarah McCarthy sarah.mccarthy@uwaterloo.ca
20 November 2023
The IACR Test-of-Time Award honors papers published at the 3 IACR flagship conferences 15 years ago which have had a lasting impact on the field. This year, we are announcing the winners for each conference separately.
The Test-of-Time award for Asiacrypt 2008 is awarded to:
Preimage Attacks on 3, 4, and 5-Pass HAVAL, by Kazumaro Aoki and Yu Sasaki, for providing new attack frameworks in symmetric-key cryptanalysis by formally introducing the Meet-in-the-Middle Preimage Attacks against hash functions, which was later generalized into key-recovery attacks against block ciphers, and collision attacks against hash functions..
For more information, see https://www.iacr.org/testoftime.
Congratulations to the winners!
Copenhagen, Denmark, 14 August - 16 August 2024
Submission deadline: 7 April 2024
Notification: 20 May 2024
Okinawa Institute of Science and Technology (OIST), Japan
The Applied Cryptography Unit (https://groups.oist.jp/appcrypto) at the Okinawa Institute of Science and Technology (OIST) is seeking to hire up to four postdoctoral scholars in cryptography.
The research unit, led by Prof. Carlos Cid, was established in 2022, to conduct research in the design and analysis of modern cryptographic primitives and schemes used to protect confidentiality and integrity of data, both in the classical and in the quantum settings. The Applied Cryptography Unit is also part of OIST Center for Quantum Technologies (https://www.oist.jp/ocqt).
To forge and develop the Unit's research activities, we are seeking to hire up to four outstanding post-doctoral researchers to join us, to work in the following topics: post-quantum / quantum cryptography (design and analysis), quantum cryptanalysis, post-quantum cryptographic techniques for privacy-preserving mechanisms.
The postdocs will be provided with funding and access to world-class facilities to pursue their research. The Unit aims to establish a highly collaborative environment, and we expect there will be several opportunities to work with other research groups at OIST, in Japan and overseas.
For more information about the role, and how to apply, see: https://www.oist.jp/careers/postdoctoral-scholars-applied-cryptography-unit
Closing date for applications:
Contact: Carlos Cid (carlos.cid@oist.jp)
More information: https://www.oist.jp/careers/postdoctoral-scholars-applied-cryptography-unit
Universitat Pompeu Fabra; Barcelona, Spain
Closing date for applications:
Contact: horacio.saggion@upf.edu
More information: https://apply.interfolio.com/135150
Bernardo David, Felix Engelmann, Tore Frederiksen, Markulf Kohlweiss, Elena Pagnin, Mikhail Volkhov
We address this limitation by introducing updatable privacy-preserving blueprint schemes (UPPB), which enhance the original notion with the ability for multiple parties to non-interactively update the private value $x$ in a blueprint. Moreover, a UPPB scheme allows for verifying that a blueprint is the result of a sequence of valid updates while revealing nothing else.
We present uBlu, an efficient instantiation of UPPB for computing a comparison between private user values and a private threshold $t$ set by the auditor, where the current value $x$ is the cumulative sum of private inputs, which enables applications such as privacy-preserving anti-money laundering and location tracking. Additionally, we show the feasibility of the notion generically for all value update functions and (binary) predicates from FHE and NIZKs.
Our main technical contribution is a technique to keep the size of primary blueprint components independent of the number of updates and reasonable for practical applications. This is achieved by elegantly extending an algebraic NIZK by Couteau and Hartmann (CRYPTO'20) with an update function and making it compatible with our additive updates. This result is of independent interest and may find additional applications thanks to the concise size of our proofs.