IACR News
Here you can see all recent updates to the IACR webpage. These updates are also available:
22 May 2023
Malik Imran, Aikata Aikata, Sujoy Sinha Roy, Samuel pagliarini
Fuchun Guo, Willy Susilo, Xiaofeng Chen, Peng Jiang, Jianchang Lai, Zhen Zhao
ChihYun Chuang, IHung Hsu, TingFang Lee
Ali Dogan, Kemal Bicakci
Alexandru Ionita
Serge Fehr, Yu-Hsuan Huang
Varun Madathil, Alessandra Scafuro
For UTXO-based cryptocurrencies, there are well-established approaches (e.g., ZCash) that guarantee full privacy to the transactors. Full privacy in UTXO means that each transaction is anonymous within the set of all private transactions ever posted on the blockchain.
In contrast, for account-based cryptocurrencies (e.g., Ethereum) full privacy, that is, privacy within the set of all accounts, seems to be impossible to achieve within the constraints of blockchain transactions (e.g., they have to fit in a block). Indeed, every approach proposed in the literature achieves only a much weaker privacy guarantee called $k-$anonymity where a transactor is private within a set of $k$ account holders. $k-$anonymity is achieved by adding $k$ accounts to the transaction, which concretely limits the anonymity guarantee to a very small constant (e.g., $~$64 for QuisQuis and $~$256 for anonymous Zether), compared to the set of all possible accounts.
In this paper, we propose a completely new approach that does not achieve anonymity by including more accounts in the transaction, but instead makes the transaction itself ``smarter''. Our key contribution is to provide a mechanism whereby a compact transaction can be used to correctly update all accounts. Intuitively, this guarantees that all accounts are equally likely to be the recipients/sender of such a transaction. We, therefore, provide the first protocol that guarantees full privacy in account-based cryptocurrencies PriFHEte
The contribution of this paper is theoretical. Our main objective is to demonstrate that achieving full privacy in account-based cryptocurrency is actually possible. We see our work as opening the door to new possibilities for anonymous account-based cryptocurrencies.
Nonetheless, in this paper, we also discuss PriFHEte's potential to be developed in practice by leveraging the power of off-chain scalability solutions such as zk rollups.
Alexandre Augusto Giron
Manuel Barbosa, Peter Schwabe
In this short note we show that an (unconditional) upper bound for the running time for Kyber exists. Computing a tight upper bound, however, is (likely to be) infeasible. We remark that the result has no real practical value, except that it may be useful for computer-assisted reasoning about Kyber using tools that require a simple proof of termination.
Julia Kastner, Julian Loss, Omar Renawi
In this work, we point out a subtle flaw in the attack of Benhamouda et al. on ACL and show, in spite of popular opinion, that it can be proven concurrently secure. Our modular proof in the algebraic group model uses an ID scheme as an intermediate step and leads to a major simplification of the complex security argument for Abe's Blind Signature scheme by Kastner et al. (PKC'22).
You Lyu, Shengli Liu
In this paper, we solve the open problem with a generic construction of two-message AKE from any CCA-secure Tagged Key Encapsulation Mechanism (TKEM). Our AKE supports state reveal and achieves IND-AA security. Given the fact that CCA-secure public-key encryption (PKE) implies CCA-secure TKEM, our AKE can be constructed from any CCA-secure PKE with proper message space. The abundant choices for CCA-secure PKE schemes lead to many IND-AA secure AKE schemes in the standard model. Moreover, following the online-extractability technique in recent work by Don et al. (Eurocrypt 2022), we can extend the Fujisaki-Okamoto transformation to transform any CPA-secure PKE into a CCA-secure Tagged KEM in the QROM model. Therefore, we obtain the first generic construction of IND-AA secure two-message AKE from CPA-secure PKE in the QROM model. This construction does not need any signature scheme, and this result is especially helpful in the post-quantum world, since the current quantum-secure PKE schemes are much more efficient than their signature counterparts.
Zhiyuan An, Haibo Tian, Chao Chen, Fangguo Zhang
Vipul Goyal, Chen-Da Liu-Zhang, Rafail Ostrovsky
Ping Wang, Yiting Su
Ghada Almashaqbeh, Rohit Chatterjee
In this paper, we investigate the relation between these two technologies; whether one can replace the other, or complement each other such that combining them brings the best of both worlds. Towards this goal, we review the quantum and unclonable polymer models, and existing unclonable cryptographic primitives. Then, we discuss whether these primitives can be built using the other technology, and show alternative constructions and notions when possible. We also offer insights and remarks for the road ahead. We believe that this study will contribute in advancing the field of unclonable cryptography on two fronts: developing new primitives, and realizing existing ones using new constructions.
Tabitha Ogilvie
We identify the dependence of HE noise on the underlying data as a critical barrier to privacy, and derive new results on the Differential Privacy under this constraint. We apply these ideas to a proof of concept HE application, ridge regression training using gradient descent, and are able to achieve privacy budgets of $\varepsilon \approx 2$ after 50 iterations.
Luke Harmon, Gaetan Delavignette, Arnab Roy, David Silva
17 May 2023
Lund University, Faculty of Engineering, Department of Electrical and Information Technology
Senior researchers will be active in the project and provide supervision. The work will primarily be funded through WASP (https://wasp-sweden.org/).
The main duties of doctoral students are to devote themselves to their research studies which includes participating in research projects and third cycle courses. The work duties can also include teaching and other departmental duties (no more than 20%).
Apply here: https://lu.varbi.com/what:job/jobID:627038/?lang=en
Closing date for applications:
Contact: Qian Guo
More information: https://lu.varbi.com/what:job/jobID:627038/?lang=en
Institute for Advancing Intelligence, TCG CREST, Kolkata
Closing date for applications:
Contact: nilanjan.datta@tcgcrest.org, avijit.dutta@tcgcrest.org, avik.chakraborti@tcgcrest.org
More information: https://www.tcgcrest.org/institutes/iai/
Rome, Italy, 14 December - 15 December 2023
Submission deadline: 31 May 2023
Notification: 31 July 2023