IACR News
Here you can see all recent updates to the IACR webpage. These updates are also available:
23 May 2022
Li Duan, Yufan Jiang, Yong Li, Jörn Müller-Quade, Andy Rupp
Alexandru Ionita
Marcel Armour, Bertram Poettering
ASAs were initially introduced by Bellare, Paterson and Rogaway in light of revelations concerning mass surveillance, as a novel attack class against the confidentiality of encryption schemes. Such an attack replaces one or more of the regular scheme algorithms with a subverted version that aims to reveal information to an adversary (engaged in mass surveillance), while remaining undetected by users. Previous work looking at ASAs against encryption schemes can be divided into two groups. ASAs against PKE schemes target key generation by creating subverted public keys that allow an adversary to recover the secret key. ASAs against symmetric encryption target the encryption algorithm and leak information through a subliminal channel in the ciphertexts. We present a new class of attack that targets the decryption algorithm of an encryption scheme for symmetric encryption and public key encryption, or the verification algorithm for an authentication scheme. We present a generic framework for subverting a cryptographic scheme between a sender and receiver, and show how a decryption oracle allows a subverter to create a subliminal channel which can be used to leak secret keys. We then show that the generic framework can be applied to authenticated encryption with associated data, message authentication schemes, public key encryption and KEM/DEM constructions.
We consider practical considerations and specific conditions that apply for particular schemes, strengthening the generic approach. Furthermore, we show how the hybrid subversion of key generation and decryption algorithms can be used to amplify the effectiveness of our decryption attack. We argue that this attack represents an attractive opportunity for a mass surveillance adversary. Our work serves to refine the ASA model and contributes to a series of papers that raises awareness and understanding about what is possible with ASAs.
affiliated workshop at CHES 2022
https://ches.iacr.org/2022/affiliated.php
20 May 2022
KU Leuven, COSIC, Belgium
The COSIC Research group at the University of Leuven in Belgium is one of the largest groups in applied cryptography. We have a strong tradition in collaborating with industry and we provide an excellent level of base funding and support. We are looking for new research professors in the area of hardware security and applied cryptography; these are prestigious positions with a reduced teaching load.
Candidates are expected to have an excellent publication record. They should present an ambitious plan to develop their research area in the COSIC team.
Junior candidates can apply for a tenure track position (assistant professor); more experienced candidates can be appointed in a more senior position.
Candidates should send a motivation letter, a brief CV (2 pages), a research plan (2 pages) and a publication list by Monday June 20 2022 to Saartje Verheyen (firstname.lastname@kuleuven.be).
Closing date for applications:
Contact: Prof. Ingrid Verbauwhede and Prof. Bart Preneel (firstname.lastname@kuleuven.be).
Multiple academic teaching positions (Lecturer/ Assistant Professor/ Associate Professor/ Professor)
Xiamen University Malaysia, Sepang, Malaysia
Xiamen University Malaysia is now seeking highly motivated, committed and qualified individuals for academic teaching positions in computer science and cyber security.
Candidates in any areas of computer science and cyber security are welcome to apply. Preferences will be given to candidates with expertise in, but not limited to, cyber security, mathematics, cryptology, network security, digital forensics. Applicants must possess a PhD degree in a related discipline.
Applicants with specific teaching and research interests in TWO OR MORE of the following areas are encouraged to apply:
- Calculus
- Linear Algebra
- Discrete Mathematics
- Probability and Statistics
- Design & Analysis of Algorithms
- Computer Composition
- Operating Systems
- Cyber Security
- Modern Cryptography
- Digital Forensics and Investigation
- Network Attack and Defence Technology
- Big Data Analytics
- Malware Analysis
- Cryptanalysis
- ARM Assembly Language
HOW TO APPLY
Applicants are invited to submit a digital application packet to: iftekhar.salam@xmu.edu.my
The subject line of your email must include: your name, relevant academic discipline, and the specific position for which you are applying for. All application packets must include the following attachments:
- Your detailed and current CV with publication (*Asterisk to indicate corresponding author, include Indexing & Quartile);
- Cover letter;
- Evidence of academic qualifications (Bachelor, Master & PhD Certificate; Bachelor, Master & PhD Transcripts and Professional Certificates);
- 3-5 Full-Text publications (if applicable);
- Teaching evaluation (if applicable);
- Two academic references (at least one of them is the applicant’s current/most recent employer).
Closing date for applications:
Contact: iftekhar.salam@xmu.edu.my
19 May 2022
CryptoLux Group, University of Luxembourg
The University of Luxembourg invites applications for a Ph.D. position in the general area of symmetric cryptography. The successful candidate will join the CryptoLux group of Prof. Alex Biryukov, which is affiliated to both the Department of Computer Science (DCS) and the Interdisciplinary Center for Security, Reliability and Trust (SnT).
Research Topics- Cryptanalysis and design of cryptographic primitives, lightweight ciphers, hash functions
- Financial cryptography (security of distributed ledgers, smart contracts)
- Privacy-enhancing technologies (Tor-like networks, privacy for cryptocurrencies, blockchains)
- White-box cryptography
- M.Sc. degree in computer science or applied mathematics with outstanding grades (GPA >= 85%)
- Strong mathematical and/or algorithmic CS background
- Some background in cryptography or information security
- Good programming skills (C/C++, Python, math tools, etc.)
- Fluent written and verbal communication skills in English
The University of Luxembourg offers a Ph.D. study program with an initial contract of 36 months, with a further possible 1-year extension if required. The successful candidate will work in one of the most international universities in the world and will have a chance to participate in a well-known security research center. The position will be available from July 2022.
Applications, written in English, should be sent by email to alex.biryukov@uni.lu. The application material should include a curriculum vitae (with photo, educational background, work experience), a brief research statement and topics of particular interest to the candidate (max. 1 page), a transcript of all modules and results from university-level courses taken (with overall GPAs) and contact information for 2-3 references.
Application deadline: 1 June 2022. Early submission is encouraged; applications will be processed upon arrival.
Closing date for applications:
Contact: Prof. Alex Biryukov (email: alex.biryukov@uni.lu)
University of Bergen
Closing date for applications:
Contact: Prof. Lilya Budaghyan, Head of the Selmer center at the Department of Informatics (firstname.surname@uib.no).
More information: https://www.jobbnorge.no/en/available-jobs/job/226570/phd-research-fellow-in-informatics-cryptology-up-to-3-positions
University of Rouen Normandie, France
We offer a 3-year fully funded Ph.D. position starting fall 2022 at University of Rouen Normandie within the LITIS lab (https://www.litislab.fr/en/) with a focus on the design and cryptanalysis of code-based and multivariate cryptographic primitives. The goal is to focus more precisely on algebraic cryptanalysis which consists in building a system of multivariate equations such that the solution set contains (part of) the secret of a cryptographic primitive. Furthermore, the algebraic modeling of several problems, such as the MinRank problem or the Rank Decoding problem, have recently witnessed important progress in their analysis. The Ph.D. candidate will pursue the analysis of various algebraic modeling on code-based or multivariate schemes (e.g. Classic McEliece, GeMSS, Rainbow, DURANDAL, MQDSS, etc).
The candidate is expected to have a strong background in mathematics, computer algebra, in particular in polynomial system solving (e.g. Gröbner basis algorithms), and cryptography. She/he must have a Master degree or equivalent related to these areas.
Funding for attending international conferences, summer schools, and visiting other research centers will also be provided.
To apply, send the following documents to Magali Bardet (magali.bardet@univ-rouen.fr) and Ayoub Otmani (ayoub.otmani@univ-rouen.fr):
- Motivation letter
- CV
- Transcripts of marks
- Up to 3 reference letters
Applications will be considered until the position is filled but a first screening of candidates will take place by May 25, 2022. Interested applicants are therefore encouraged to send their documents before that date.
Keywords. Post-quantum cryptography, code-based cryptography, multivariate cryptography, MinRank problem, algebraic cryptanalysis, Gröbner basis.
Closing date for applications:
Contact:
- Magali Bardet (magali.bardet@univ-rouen.fr)
- Ayoub Otmani (ayoub.otmani@univ-rouen.fr)
More information: https://www.litislab.fr/en/
17 May 2022
Léonard Lys, Maria Potop-Butucaru
Clément Fanjas, Clément Gaine, Driss Aboulkassimi, Simon Pontié, Olivier Potin
Lucianna Kiffer, Rajmohan Rajaraman, abhi shelat
To establish consistency, the prior analysis of Pass, Seeman and shelat required a careful counting of certain combinatorial events that was difficult to apply to variations of Nakamoto. The work of Garay, Kiayas, and Leonardas provides another method of analyzing the blockchain under both a synchronous and partially synchronous setting.
The contribution of this paper is the development of a simple Markov-chain based method for analyzing consistency properties of blockchain protocols. The method includes a formal way of stating strong concentration bounds as well as easy ways to concretely compute the bounds. We use our new method to answer a number of basic questions about consistency of blockchains:
• Our new analysis provides a tighter guarantee on the consistency property of Nakamoto’s protocol, including for parameter regimes which previous work could not consider; • We analyze a family of delaying attacks and extend them to other protocols; • We analyze how long a participant should wait before considering a high-value transaction “confirmed”; • We analyze the consistency of CliqueChain, a variation of the Chainweb system; • We provide the first rigorous consistency analysis of GHOST under the partially synchronous setting and also analyze a folklore "balancing"-attack.
In each case, we use our framework to experimentally analyze the consensus bounds for various network delay parameters and adversarial computing percentages.
We hope our techniques enable authors of future blockchain proposals to provide a more rigorous analysis of their schemes.
Loïc Masure, Olivier Rioul, François-Xavier Standaert
Lionel Beltrando, Maria Potop-Butucaru, Jose Alfaro
Laltu Sardar, Sushmita Ruj
We design a forward private DSE scheme that supports conjunctive keyword search. At the heart of the construction is our proposed data structure called the dynamic interval accumulation tree (DIA tree). It is an accumulator-based authentication tree that efficiently returns both membership and non-membership proofs. Using the DIA tree, we can convert any single keyword forward private DSE scheme to a verifiable forward private DSE scheme that can support conjunctive queries as well. Our proposed scheme has the same storage as the base DSE scheme and low computational overhead on the client-side. We have shown the efficiency of our design by comparing it with existing conjunctive DSE schemes. The comparison also shows that our scheme is suitable for practical use.
Sisi Duan, Haibin Zhang
We demonstrate the challenges of extending static BFT to dynamic BFT. Then we design and implement Dyno, a highly efficient dynamic BFT protocol under the partial synchrony model. We show that Dyno can seamlessly handle membership changes without incurring performance degradation.
Liam Eagen
Theo von Arx, Kenneth G. Paterson
Maria Ferrara, Antonio Tortora
Yupu Hu, Shanshan Zhang, Baocang Wang, Siyue Dong
In this paper we only consider the simple case of \((n,t)\) threshold secret sharing. We find following 5 facts about CKO+21 scheme, which are the basic reasons we negate the security proof of CKO+21 scheme. (1) In the expression of share of CKO+21 scheme, some bottom Shamir share is simply included, rather than encapsulated. (2) The leakage of the share is not a random leakage, but rather related to the inquiry of the attacker, that is, a chosen leakage. (3) The permitted leakage length of each share is proportional to the share length. (4) The bottom Shamir scheme has such special feature: when the length of the share $l^{*}$ is kept unchanged, it can make the number of shares $n$, the threshold value $t$, and the difference value $n-t+1$ any large, as long as $t
\setlength{\parindent}{2em}In this paper we point that, CKO+21 scheme didn’t successfully prove its security. As long as the bottom Shamir secret sharing scheme satisfies both “leakage recoverability” and “contaminated leakage irrecoverability”, the security proof of CKO+21 scheme is wrong. It needs to be pointed out that “leakage recoverability” and “contaminated leakage irrecoverability” cannot be naturally negated by “privacy” of Shamir scheme, and up to now there is not a proof that Shamir scheme doesn’t satisfy “leakage recoverability” or “contaminated leakage irrecoverability”.
The detailed contribution of this paper is as follow. CKO+21 scheme designed several leakage models: \(\mathsf{Leak}{\mathsf{B}_0}\),\(\mathsf{Leak}{\mathsf{A}_1}\),\(\mathsf{Leak}{\mathsf{B}_1}\),\(\mathsf{Leak}{\mathsf{A}_2}\),\(\mathsf{Leak}{\mathsf{B}_2}\),$\cdots$,\(\mathsf{Leak}{\mathsf{A}_h}\),\(\mathsf{Leak}{\mathsf{B}_h}\),\(\mathsf{Leak}{\mathsf{C}}\), where \(\mathsf{Leak}{\mathsf{B}_0}\) is the practical leakage model, \(\mathsf{Leak}{\mathsf{C}}\) is a leakage model independent of the secret message. CKO+21 scheme claimed that an attacker cannot distinguish two adjacent leakage models, so the scheme is “leakage resilient”. We point that, if the bottom Shamir scheme satisfies both “leakage recoverability” and “contaminated leakage irrecoverability”, the attacker can distinguish \(\mathsf{Leak}{\mathsf{B}_0}\) and \(\mathsf{Leak}{\mathsf{A}_1}\) with non-negligible probability.
Besides, if the bottom Shamir scheme doesn’t satisfy “leakage recoverability”. Shamir scheme itself has some ability to resist leakage, and the bulky structure of CKO+21 scheme is not necessary.