IACR News
Here you can see all recent updates to the IACR webpage. These updates are also available:
16 March 2023
Farshid Haidary Makoui, T. Aaron Gulliver, Mohammad, Dakhilalian
Marc Rivinius, Pascal Reisert, Sebastian Hasler, Ralf Kuesters
Farshid Haidary Makoui, T. Aaron Gulliver, Mohammad Dakhilalian
Zhen Gu, Wen-jie Lu, Cheng Hong
The call for proposals is now out at: https://crypto.iacr.org/2023/affiliated.php
The registration site is now open. To avoid late fees please register before March 30th.
https://eurocrypt.iacr.org/2023/registration.php
15 March 2023
Mirek Kutylowski, Giuseppe Persiano, Duong Hieu Phan, Moti Yung, Marcin Zawada
In this work, we postulate a stronger cryptographic control setting where encryption does not exist (or is neutralized) since all communication is passed through the Dictator in, essentially, cleartext mode (or otherwise, when secure channels to and from the Dictator are the only confidentiality mechanism). Messages are only authenticated to assure recipients of the identity of the sender. We ask whether security against the Dictator still exists, even under such a~strict regime which allows only authentication (i.e., authenticated/ signed messages) to pass end-to-end, and where received messages are determined by/ known to the Dictator, and the Dictator also eventually gets all keys to verify compliance of past signing. To frustrate the Dictator, this authenticated message setting gives rise to the possible notion of anamorphic channels inside signature and authentication schemes, where parties attempt to send undetectable secure messages (or other values) using signature tags which are indistinguishable from regular tags. We define and present implementation of schemes for anamorphic signature and authentication; these are applicable to existing and standardized signature and authentication schemes which were designed independently of the notion of anamorphic messages. Further, some cornerstone constructions of the foundations of signatures, in fact, introduce anamorphism.
Jian Liu, Yanjun Li, Runyi Liu, Jian Zou, Zhiqiang Wang
Federico Canale, María Naya-Plasencia
Rahul Mishra, Bhupendra Singh, Radhakrishnan Delhibabu
Marc Fischlin, Jonas von der Heyden, Marian Margraf, Frank Morgner, Andreas Wallner, Holger Bock
In this work we present PQ-EAC, a quantum-resistant version of the EAC protocol. We show how to achieve post-quantum confidentiality and authentication without sacrificing real-world usability on smart cards. To ease adoption, we present two main versions of PQ-EAC: One that uses signatures for authentication and one where authentication is facilitated using long-term KEM keys. Both versions can be adapted to achieve forward secrecy and to reduce round complexity. To ensure backwards-compatibility, PQ-EAC can be implemented using only Application Protocol Data Units (APDUs) specified for EAC in standard BSI TR-03110. Merely the protocol messages needed to achieve forward secrecy require an additional APDU not specified in TR-03110. We prove security of all versions in the real-or-random model of Bellare and Rogaway.
To show real-world practicality of PQ-EAC we have implemented a version using signatures on an ARM SC300 security controller, which is typically deployed in MRTDs. We also implemented PQ-EAC on a VISOCORE terminal for border control. We then conducted several experiments to evaluate the performance of PQ-EAC executed between chip and terminal under various real-world conditions. Our results strongly suggest that PQ-EAC is efficient enough for use in border control.
Yoshinori Aono, Junji Shikata
Leonard Assouline, Brice Minaud
In this article, we introduce the notion of weighted ORAM, which supports the storage of blocks of different sizes. In a standard ORAM scheme, each data block has a fixed size $B$. In weighted ORAM, the size (or weight) of a data block is an arbitrary integer $w_i \in [1,B]$. The parameters of the weighted ORAM are entirely determined by an upper bound $B$ on the block size, and an upper bound $N$ on the total weight $\sum w_i$ of all blocks\textemdash regardless of the distribution of individual weights $w_i$. During write queries, the client is allowed to arbitrarily change the size of the queried data block, as long as the previous upper bounds continue to hold.
We introduce a framework to build efficient weighted ORAM schemes, based on an underlying standard ORAM satisfying a certain suitability criterion. This criterion is fulfilled by various Tree ORAM schemes, including Simple ORAM and Path ORAM. We deduce several instantiations of weighted ORAM, with very little overhead compared to standard ORAM. As a direct application, we obtain efficient SSE constructions with attractive security properties.
Gang Xu, Shiyuan Xu, Yibo Cao, Ke Xiao, Xiu-Bo Chen, Mianxiong Dong, Shui Yu
Cody Freitag, Ashrujit Ghoshal, Ilan Komargodski
The most well-known methods for designing variable-input length hash function families from a fixed idealized function are the Merkle-Damgård and Sponge designs. The former underlies the SHA-1 and SHA-2 constructions and the latter underlies SHA-3. Unfortunately, recent works (Coretti et al. EUROCRYPT 2018, Coretti et al. CRYPTO 2018) show non-trivial time-space tradeoff attacks for finding collisions for both. Thus, this forces a parameter blowup (i.e., efficiency loss) for reaching a certain desired level of security. We ask whether it is possible to build families of keyed hash functions which are provably resistant to any non-trivial time-space tradeoff attacks for finding collisions, without incurring significant efficiency costs.
We present several new constructions of keyed hash functions that are provably resistant to any non-trivial time-space tradeoff attacks for finding collisions. Our constructions provide various tradeoffs between their efficiency and the range of parameters where they achieve optimal security for collision resistance. Our main technical contribution is proving optimal security bounds for converting a hash function with a fixed-sized input to a keyed hash function with (potentially larger) fixed-size input. We then use this keyed function as the underlying primitive inside the standard MD and Merkle tree constructions. We strongly believe that this paradigm of using a keyed inner hash function in these constructions is the right one, for which non-uniform security has not been analyzed prior to this work.
Yibin Yang, Mohsen Minaei, Srinivasan Raghuraman, Ranjit Kumaresan, Mahdi Zamani
We introduce the notion of a programmable payment channel (PPC) that allows two parties to agree on a smart contract off-chain specifying the conditions on which the transactions can happen. If either party violates any of the terms, the other party can later deploy the contract on-chain to receive a remedy as agreed upon in the contract. Specifically, our PPC supports programmable payments where only one party deposits to the agreed off-chain contract, enabling lightweight payments. We further show that any two-party contract (even ones with two party deposits) can be implemented with PPC, by a compiler and associated protocol, allowing the parties to use their pre-deposited on-chain collaterals for any off-chain interaction potentially not anticipated at the time of channel setup. We formalize and prove the security and correctness of our protocol under the UC framework. We implement our protocol on Ethereum using accumulators to achieve efficient concurrent programmable transactions and measure the gas overhead of a hash-time-lock PPC contract to be < 100K which can be amortized over many off-chain payments.
10 March 2023
Leiden University, LIACS; Leiden, The Netherlands
The successful applicant should be a motivated university graduate who is a top performer among his/her peers and has an excellent education and/or research track record proven by relevant experience, publications, etc. The applicant is expected to have:
For more information about the position, please see: https://www.universiteitleiden.nl/vacatures/2023/kwartaal-1/23-124phd-candidate-privacy-preserving-machine-learning
Closing date for applications:
Contact: Eleftheria Makri: e.makri@liacs.leidenuniv.nl
More information: https://www.universiteitleiden.nl/vacatures/2023/kwartaal-1/23-124phd-candidate-privacy-preserving-machine-learning
NEC Laboratories Europe
We are looking for a Research Associate to contribute, in the frame of an EU funded project, to the research and the development of solutions in the area of security and privacy, with a special focus on distributed systems and blockchain security.
Required Skills and Experience
- Strong experience in system security and distributed systems
- Experience in blockchain technologies.
- Experience in cryptography
- Experience in software development with programming languages such as Python, Golang, Java, or C/C++
- Excellent interpersonal and communication skills in English
Our work ranges from foundational research and IPR creation to prototype development for NEC products and services.
The Security group (SEC) is considered one of the pioneers in Europe in the area of security and privacy R&D with its top researchers in the fields of cloud security, blockchain security, system security, and applied cryptography.
At NEC Laboratories Europe, we provide a collaborative, team-working environment that supports your career aspirations. Our working language is English. The position is initially limited to two years.
NEC Laboratories Europe is located in the beautiful city of Heidelberg, Germany. Home office schemes within the country may be offered. Heidelberg is an international and lively city with a large number of exciting cultural, entertainment, and outdoor activities.
Application deadline: March 27, 2023
For further detail and how to apply, see:
https://jobs.neclab.eu/jobs/openings/staff/NEC-NLE-2301-461-SEC-1-Research_Associate_%5b2301_461_SEC%5d.pdf
Closing date for applications:
Contact: Giorgia Marson
More information: https://jobs.neclab.eu/jobs/openings/staff/NEC-NLE-2301-461-SEC-1-Research_Associate_%5b2301_461_SEC%5d.pdf
Virtual event, Anywhere on Earth, 21 June - 22 June 2023
Submission deadline: 1 May 2023
Notification: 19 March 2023