IACR News
Here you can see all recent updates to the IACR webpage. These updates are also available:
08 July 2022
Sukanta Dey, Jungmin Park, Nitin Pundir, Dipayan Saha, Amit Mazumder Shuvo, Dhwani Mehta, Navid Asadi, Fahim Rahman, Farimah Farahmandi, Mark Tehranipoor
07 July 2022
Cristian-Alexandru Botocan
In the deep learning-based profiling attack, a core problem is finding efficient neural network architectures to evaluate an implementation's security correctly. Unfortunately, this process is time-consuming, and a different neural network configuration usually needs to be defined for every target. Hence, we propose the following process: train a separate autoencoder for each dataset obtained from different cryptographic implementations and devices to receive an encoded version for each one. After that, define a universal model that can break multiple (encoded) datasets. Thus, instead of finding dataset-specific neural network architectures, we reduce the effort to find autoencoders to encode the datasets and a single neural network to break~them.
Russell W. F. Lai, Giulio Malavolta, Nicholas Spooner
To prove this result, we devise a new quantum rewinding strategy, the first that allows for rewinding across many rounds. This technique applies to any protocol satisfying natural multi-round generalizations of special soundness and collapsing. For our main result, we show that recent Bulletproofs-like protocols based on lattices satisfy these properties, and are hence sound against quantum adversaries.
David Chaum, Mario Larangeira, Mario Yaksetig
Yuval Ishai, Dakshita Khurana, Amit Sahai, Akshayaram Srinivasan
\item A two-round multiparty protocol in the OT correlations model, making a black-box use of a semi-malicious protocol. This improves over a similar protocol of the authors (Crypto 2021) by eliminating an adaptive security requirement and replacing nonstandard multiparty OT correlations by standard ones. As an application, we get 2-round protocols for arithmetic branching programs that make a black-box use of the underlying field. \end{itemize}
As a contribution of independent interest, we provide a new variant of the IPS compiler (Ishai, Prabhakaran and Sahai, Crypto 2008) in the two-round setting, where we relax requirements on the IPS ``inner protocol'' by strengthening the ``outer protocol''.
Hyunji Kim, Sejin Lim, Yeajun Kang, Wonwoong Kim, Hwajeong Seo
Akshima, Siyao Guo, Qipeng Liu
Very recently, Ghoshal and Komargodski (CRYPTO 22) confirmed STB conjecture for all constant values of $B$, and provided an ${O}(S^4TB^2/2^n+T^2/2^n)$ bound for all choices of $B$.
In this work, we prove an ${O}((STB/2^n)\cdot\max\{1,ST^2/2^n\}+ T^2/2^n)$ bound for every $2< B < T$. Our bound confirms the STB conjecture for $ST^2\leq 2^n$, and is optimal up to a factor of $S$ for $ST^2>2^n$ (note as $T^2$ is always at most $2^n$, otherwise finding a collision is trivial by the birthday attack). Our result subsumes all previous upper bounds for all ranges of parameters except for $B={O}(1)$ and $ST^2>2^n$.
We obtain our results by adopting and refining the technique of Chung, Guo, Liu, and Qian (FOCS 2020). Our approach yields more modular proofs and sheds light on how to bypass the limitations of prior techniques.
Along the way, we obtain a considerably simpler and illuminating proof for $B=2$, recovering the main result of Akshima, Cash, Drucker and Wee.
Prabhanjan Ananth, Fatih Kaleoglu, Xingjian Li, Qipeng Liu, Mark Zhandry
We make progress towards establishing the feasibility of unclonable encryption.
- We show that encryption schemes satisfying unclonable indistinguishability exist unconditionally in the quantum random oracle model.
- Towards understanding the necessity of oracles, we present a negative result stipulating that a large class of encryption schemes cannot satisfy unclonable indistinguishability.
- Finally, we also establish the feasibility of another closely related primitive: copy-protection for single-bit output point functions. Prior works only established the feasibility of copy-protection for multi-bit output point functions or they achieved constant security error for single-bit output point functions.
Ilan Komargodski, Elaine Shi
In this work, we show that any Turing machine computation can be generically compiled into a differentially oblivious one with only doubly logarithmic overhead. More precisely, given a Turing machine that makes $N$ transitions, the compiled Turing machine makes $O(N \cdot \log\log N)$ transitions in total and the physical head movements sequence satisfies $(\epsilon,\delta)$-differential privacy (for a constant $\epsilon$ and a negligible $\delta$). We additionally show that $\Omega(\log\log N)$ overhead is necessary in a natural range of parameters (and in the balls and bins model).
As a corollary, we show that there exist natural data structures such as stack and queues (supporting online operations) on $N$ elements for which there is a differentially oblivious implementation on a Turing machine incurring amortized $O(\log\log N)$ overhead per operation, while it is known that any oblivious implementation must consume $\Omega(\log N)$ operations unconditionally even on a RAM. Therefore, we obtain the first \emph{unconditional} separation between obliviousness and differential obliviousness in the most natural setting of parameters where $\epsilon$ is a constant and $\delta$ is negligible. Before this work, such a separation was only known in the balls and bins model. Note that the lower bound applies in the RAM model while our upper bound is in the Turing machine model, making our separation stronger.
Jakob Feldtkeller, David Knichel, Pascal Sasdrich, Amir Moradi, Tim Güneysu
Lipeng Wan, Fangyu Zheng, Guang Fan, Rong Wei, Lili Gao, Jiankuo Dong, Jingqiang Lin, Yuewu Wang
After investigating and analysing the workload of the commercial off-the-shelf AI accelerators, we utilize NVIDIA's AI accelerator, Tensor Core, to accelerate the polynomial multiplication, usually the most time-consuming part in lattice-based cryptography. A series of measures are taken, such as accommodating the matrix-multiply-and-add mode of Tensor Core and making a trade-off between precision and performance, to leverage Tensor Core as a high-performance NTT box performing NTT/INTT through CUDA C++ WMMA API. Meanwhile, we take CRYSTALS-Kyber, one of the NIST PQC 3rd round candidates, as a case study on RTX 3080 with the Ampere Tensor Core. The empirical results show that the defined NTT of polynomial vector ($n=256,k=4$) with our NTT box obtains a speedup of around 6.47x that of the state-of-the-art implementation on the same platform.
Gustavo Banegas, Valerie Gilchrist, Benjamin Smith
Aurélien Greuet, Simon Montoya, Clémence Vermeersch
Michael Rosenberg, Jacob White, Christina Garman, Ian Miers
We present and build $\texttt{zk-creds}$, a protocol that uses general-purpose zero-knowledge proofs to 1) remove the need for credential issuers to hold signing keys: credentials can be issued via a transparency log, Byzantine system, or even a blockchain; 2) convert existing identity documents into anonymous credentials without modifying documents or coordinating with their issuing authority; 3) allow for flexible, composable, and complex identity statements over multiple credentials. Concretely, identity assertions using $\texttt{zk-creds}$ take less than 300ms in a real-world scenario of using a passport to anonymously access age-restricted videos.
Myungsun Kim
Foteini Baldimtsi, Aggelos Kiayias, Katerina Samari
We present the first scheme that obviates these restrictions in the secret-key marking model, i.e., the setting where extraction is performed using a private extraction key. Our construction offers constant time extraction complexity with constant size keys and ciphertexts and is secure under standard assumptions, namely the Decisional Composite Residuosity Assumption [Eurocrypt '99] and the Decisional Diffie Hellman in prime order subgroups of square higher order residues.
Christoph Hagen, Christian Weinert, Christoph Sendner, Alexandra Dmitrienko, Thomas Schneider
Our study of three popular messengers (WhatsApp, Signal, and Telegram) shows that large-scale crawling attacks are (still) possible. Using an accurate database of mobile phone number prefixes and very few resources, we queried 10% of US mobile phone numbers for WhatsApp and 100% for Signal. For Telegram we find that its API exposes a wide range of sensitive information, even about numbers not registered with the service. We present interesting (cross-messenger) usage statistics, which also reveal that very few users change the default privacy settings.
Furthermore, we demonstrate that currently deployed hashing-based contact discovery protocols are severely broken by comparing three methods for efficient hash reversal. Most notably, we show that with the password cracking tool "JTR" we can iterate through the entire world-wide mobile phone number space in <150s on a consumer-grade GPU. We also propose a significantly improved rainbow table construction for non-uniformly distributed input domains that is of independent interest.
Regarding mitigations, we most notably propose two novel rate-limiting schemes: our incremental contact discovery for services without server-side contact storage strictly improves over Signal's current approach while being compatible with private set intersection, whereas our differential scheme allows even stricter rate limits at the overhead for service providers to store a small constant-size state that does not reveal any contact information.
Shanxiang Lyu, Ling Liu, Junzuo Lai, Cong Ling, Hao Chen
06 July 2022
(Old) Ottawa, Canada, 12 December - 14 December 2022
Submission deadline: 23 August 2022
Notification: 28 October 2022
Technology Innovation Institute (TII) - Abu Dhabi, UAE
Technology Innovation Institute (TII) is a publicly funded research institute, based in Abu Dhabi, United Arab Emirates. It is home to a diverse community of leading scientists, engineers, mathematicians, and researchers from across the globe, transforming problems and roadblocks into pioneering research and technology prototypes that help move society ahead.
Cryptography Research Centre
In our connected digital world, secure and reliable cryptography is the foundation of digital information security and data integrity. We address the world’s most pressing cryptographic questions. Our work covers post-quantum cryptography, lightweight cryptography, cloud encryption schemes, secure protocols, quantum cryptographic technologies and cryptanalysis.
Position: Senior MPC Researcher
Skills required for the job
Closing date for applications:
Contact: Mehdi Messaoudi - Talent Acquisition Manager
Email: mehdi.messaoudi@tii.ae