## IACR News

Here you can see all recent updates to the IACR webpage. These updates are also available:

#### 29 July 2024

###### Kaartik Bhushan, Alexis Korb, Amit Sahai

ePrint ReportAs sFE implies regular FE, all known constructions of sFE and FE for $\mathsf{P/Poly}$ require strong cryptographic assumptions which are powerful enough to build indistinguishability obfuscation. In contrast, bounded-collusion FE, in which the adversary is restricted to making at most $Q$ function queries for some polynomial $Q$ determined at setup, can be built from the minimal assumptions of public-key encryption (for public-key FE) [Sahai and Seyalioglu, CCS 2010; Gorbunov, Vaikuntanathan, and Wee, CRYPTO 2012] and secret-key encryption (for secret-key FE)[Ananth, Vaikuntanathan, TCC 2019].

In this paper, we introduce and build bounded-collusion streaming FE for any polynomial bound $Q$ from the same minimal assumptions of public-key encryption (for public-key sFE) and secret-key encryption (for secret-key sFE). Similarly to the original sFE paper of Guan, Korb, and Sahai, our scheme satisfies semi-adaptive-function-selective security which is similar to standard adaptive indistinguishability-based security except that we require all functions to be queried before any of the challenge messages.

Along the way, our work also replaces a key ingredient (called $\mathsf{One}\text{-}\mathsf{sFE}$) from the original work of Guan, Korb, and Sahai with a much simpler construction based on garbled circuits.

###### CHANGCHANG DING, Zheming Fu

ePrint Report###### Julius Hermelink, Silvan Streit, Erik Mårtensson, Richard Petri

ePrint ReportIn this work, we define distribution hints; a type of hint that allows modelling probabilistic information. These hints generalize most previously defined hints and the information obtained in several attacks.

We define two solvers for our hints; one is based on belief propagation and the other one uses a greedy approach. We prove that the latter is a computationally less expensive approximation of the former and that previous algorithms used for specific attacks may be seen as special cases of our solvers. Thereby, we provide a systematization of previously obtained information and used algorithms in real-world side-channel attacks.

In contrast to lattice-based approaches, our framework is not limited to value leakage. For example, it can deal with noisy Hamming weight leakage or partially incorrect information. Moreover, it improves upon the recovery of the secret key from approximate hints in the form they arise in real-world attacks. Our framework has several practical applications: We exemplarily show that a recent attack can be improved; we reduce the number of traces and corresponding ciphertexts and increase the noise resistance. Further, we explain how distribution hints could be applied in the context of previous attacks and outline a potential new attack.

###### Quang Dao, Justin Thaler

ePrint ReportIn this setting, we describe an optimization to the sum-check prover that substantially reduces the cost coming from the $\text{eq}(w, x)$ factor. Our work further improves on a prior optimization by Gruen (ePrint 2023), and in the small-field case, can be combined with additional optimizations by Bagad, Domb, and Thaler (ePrint 2024), and Dao and Thaler (ePrint 2024).

Over large prime-order fields, our optimization eliminates roughly $2^{n + 1}$ field multiplications compared to a standard linear-time implementation of the prover, and roughly $2^{n-1}$ field multiplications when considered on top of Gruen's optimization. These savings are about a 25% (respectively 10%) end-to-end prover speedup in common use cases, and potentially even larger when working over binary tower fields.

###### Mohammed Alghazwi, Tariq Bontekoe, Leon Visscher, Fatih Turkmen

ePrint ReportWe present the first, general definition for collaborative commit-and-prove NIZK (CP-NIZK) proofs of knowledge and construct distributed protocols to enable their realization. We implement our protocols for two commonly used NIZKs, Groth16 and Bulletproofs, and evaluate their practicality in a variety of computational settings. Our findings indicate that composability adds only minor overhead, especially for large circuits. We experimented with our construction in an application setting, and when compared to prior works, our protocols reduce latency by 18–55× while requiring only a fraction (0.2%) of the communication.

###### Michael Rosenberg, Tushar Mopuri, Hossein Hafezi, Ian Miers, Pratyush Mishra

ePrint ReportFinally, we also apply Hᴇᴋᴀᴛᴏɴ to two applications of real-world interest: proofs of batched insertion for a verifiable key directory and proving correctness of RAM computations. In both cases, Hᴇᴋᴀᴛᴏɴ is able to scale to handle realistic workloads with better efficiency than prior work.

###### Michael Walter

ePrint Report###### Daniel de Haro Moraes, Joao Paulo Aragao Pereira, Bruno Estolano Grossi, Gustavo Mirapalheta, George Marcel Monteiro Arcuri Smetana, Wesley Rodrigues, Courtnay Nery Guimarães Jr., Bruno Domingues ...

ePrint Report###### Zhengjun Cao, Lihua Liu

ePrint Report###### Sergiu Carpov

ePrint Report###### Santiago Arranz Olmos, Gilles Barthe, Lionel Blatter, Benjamin Grégoire, Vincent Laporte

ePrint Report###### Feng Zhou, Hua Chen, Limin Fan

ePrint Report###### Daphné Trama, Pierre-Emmanuel Clet, Aymen Boudguiga, Renaud Sirdey

ePrint Report###### Jelle Vos, Mauro Conti, Zekeriya Erkin

ePrint Report###### Theophilus Agama

ePrint Report#### 28 July 2024

###### Sapporo, Japan, 17 December - 19 December 2024

Event CalendarSubmission deadline: 16 August 2024

Notification: 11 October 2024

#### 27 July 2024

###### Dfns

Job Posting

- As a Lead Cryptographer, you will:
- Carry out fundamental and applied research with the research team.
- Act as a powerhouse of ideas on all cryptographic and research issues.
- Collaborate with the research and engineering team on technical research tasks.
More information on Dfns Labs and its affiliated projects: dfns.co/labs

**Closing date for applications:****Contact:**Christopher Grilhault des Fontaines chris@dfns.co**More information:**https://www.welcometothejungle.com/en/companies/dfns/jobs/lead-cryptographer_paris?q=577351ed68dbf939d46f6cf0a1b9fc04&o=f45742ac-fac0-4c1b-8afc-7968f5378d33

###### CIMA.science

Job Posting**Closing date for applications:**

**Contact:** Alfio Lanuto
(OBJECT: System developer)

**More information:** https://cima.science

###### Input-Output Global

Job Posting**Summary**

As a Cryptographic Engineer in Applied Cryptography, you will play a vital role in developing and implementing cryptographic solutions. You'll work alongside a team of talented individuals, contributing to various projects ranging from prototyping new cryptographic products to optimizing existing ones. You will collaborate closely with software architects, product managers, and other team members to successfully deliver high-quality cryptographic solutions that meet market demands.

You will need to have a strong foundation in engineering principles and a keen interest in cryptography. This role offers an exciting opportunity to work on cutting-edge technologies while continuously learning and growing in applied cryptography.

**Duties**

As a Cryptographic Engineer, you'll play a pivotal role in implementing Zero-Knowledge (ZK) circuits tailored for integration within the Midnight chain. Your focus will involve leveraging recursive proof technologies, particularly those based on Halo2, to create proofs regarding the Midnight state. These proofs are designed to interface with other ecosystems, such as Cardano, providing a secure and efficient means to interact and exchange information across platforms. Your duties will include:

**Closing date for applications:**

**Contact:** Marios Nicolaides

**More information:** https://apply.workable.com/io-global/j/E68F9E4337/

###### University of Wollongong, Australia

Job Posting**Closing date for applications:**

**Contact:** Prof. Willy Susilo

**More information:** https://www.uow.edu.au/about/jobs/jobs-available/#en/sites/CX_1/requisitions/preview/4659/?