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05 September 2023
Virginia Tech, Department of Mathematics; Blacksburg, Virginia, USA
The Department of Mathematics at Virginia Tech (http://www.math.vt.edu/) invites applications for a tenure-track faculty position in Post-Quantum Cryptography and Coding Theory with a start date of August 10, 2024, at its Blacksburg, VA, campus. The successful candidate will have a strong background in post-quantum cryptography, algebraic coding theory, or closely related topics. Possible specialties include but are not limited to applied algebra, algebraic geometry, combinatorics, number theory, coding theory, cryptography, or a closely related area.
Appointment as an Assistant Professor of Mathematics is anticipated, but exceptional senior candidates will be considered for Associate Professor of Mathematics or Professor of Mathematics positions. Job requirements include a Ph.D. in mathematics or a related field at the time of appointment and an active research program, or, for a new Ph.D., strong promise for developing an active research program. The successful candidate will be expected to establish a distinguished research program and to provide effective instruction and advising to a diverse population of undergraduate and graduate students. Additional responsibilities include continuing development of professional capabilities and scholarly activities, including travel to attend conferences and meetings, participation in the department, college, university, and professional service. The successful candidate will have the opportunity to engage in interdisciplinary research, curriculum development, or outreach initiatives with other members of the Virginia Tech faculty.
An online application is required. To apply, please visit www.jobs.vt.edu, select “Apply Now,” and search by posting number 526909. Please include a cover letter, a CV, a research statement, a teaching statement, and a diversity statement as part of the online application. Each applicant should follow the instructions in the online application system to request that at least three references submit letters of recommendation.
Applications received by 11:59 pm EST on September 29, 2023, will receive full consideration.
Closing date for applications:
Contact: Sarah McDearis (sworl9@vt.edu)
More information: https://careers.pageuppeople.com/968/cw/en-us/job/526909/assistant-associate-full-professor
Institute for Cyber Security, University of New South Wales (UNSW), Australia
The UNSW Institute for Cyber Security wishes to offer a PhD scholarship for applicants with outstanding research potential and an interest in quantum-safe security measures for IoT deployments. This PhD scholarship is available to applicants who are interested in undertaking research for an academic collaboration project between UNSW and CSIRO, led by Senior Lecturer Dr Arash Shaghaghi and Professor Sanjay Jha. Proposals are particularly welcome from applicants who are interested in researching practical solutions that enhance the resiliency of IoT deployments within intelligent transportation against quantum-based attacks. The project will develop a systematic approach and devise a testbed for evaluating quantum-based attacks against IoT deployments in critical infrastructure. The project’s findings will inform quantum-safe migrations in intelligent transport systems both in Australia and internationally.
AmountThe scholarship stipend will be equivalent to the value of a Research Training Program Scholarship (for 2023, this rate is 29,863 AUD p.a.), plus faculty top-up (5,000 AUD p.a.). These scholarships generally receive favourable tax treatment.
TenureThe starting date is flexible. Up to 3.5 years, subject to confirmation of candidature and satisfactory progress.
Selection criteriaApplicants must possess:
- an undergraduate degree in cybersecurity or a related discipline with a minimum Honours Class II, Division (I) that includes a substantial research component (or equivalent); or
- a postgraduate qualification in cybersecurity or a related discipline (including a substantial research component) with an average that equates to a minimum Distinction average at UNSW (75%); or
- equivalent research or professional experience, supported by references and a detailed CV.
Closing date for applications:
Contact: Dr Arash Shaghaghi (a.shaghaghi@unsw.edu.au)
University College Dublin, School of Computer Science, Dublin, Ireland
Closing date for applications:
Contact: Madhusanka Liyanage
More information: https://www.ucd.ie/workatucd/jobs/
04 September 2023
Erkan Tairi, Pedro Moreno-Sanchez, Clara Schneidewind
To help this, we present LedgerLocks, a framework for the secure design of AS-based blockchain applications in the presence of a realistic blockchain. LedgerLocks defines the concept of AS-locked transactions, transactions whose publication is bound to the knowledge of a cryptographic secret. We argue that AS-locked transactions are the common building block of AS-based blockchain protocols and we define $\mathcal{G}_{\mathsf{LedgerLocks}}$, a realistic ledger model in the Universal Composability framework with built-in support for AS-locked transactions. As LedgerLocks abstracts from the cryptographic realization of AS-locked transactions, it allows protocol designers to focus on the blockchain-specific security considerations instead.
Gregor Leander, Shahram Rasoolzadeh, Lukas Stennes
Sietse Ringers
Haiyang Xue, Man Ho Au, Mengling Liu, Kwan Yin Chan, Handong Cui, Xiang Xie, Tsz Hon Yuen, Chengru Zhang
In this paper, we design a novel MtA by revisiting the Joye-Libert (JL) cryptosystem. Specifically, we revisit JL encryption and propose a JL-based commitment, then give efficient zero-knowledge proofs for JL cryptosystem which are the first to have standard soundness. Our new MtA offers the best time-space complexity trade-off among all existing MtA constructions. It outperforms state-of-the-art constructions from Paillier by a factor of $1.85$ to $2$ in bandwidth and $1.2$ to $1.7$ in computation. It is $7\times$ faster than those based on Castagnos-Laguillaumie encryption only at the cost of $2\times$ more bandwidth. While our MtA is slower than OT-based constructions, it saves $18.7\times$ in bandwidth requirement. In addition, we also design a batch version of MtA to further reduce the amotised time and space cost by another $25$%.
Debajyoti Das, Claudia Diaz, Aggelos Kiayias, Thomas Zacharias
We are the first to close that gap and provide a formal analysis. We provide two indistinguishability based definitions (of sender anonymity), namely pairwise unlinkability and user unlinkability, tuned specifically for continuous stop-and-go mixnets. We derive the adversarial advantage as a function of the protocol parameters for the two definitions. We show that there is a fundamental lower bound on the adversarial advantage $\delta$ for pairwise unlinkability; however, strong user unlinkability (negligible adversarial advantage) can be achieved if the users message rate ($\lambda_u$) is proportional to message processing rate ($\lambda$) on the nodes.
Animesh Singh, Smita Das, Anirban Chakraborty, Rajat Sadhukhan, Ayantika Chatterjee, Debdeep Mukhopadhyay
02 September 2023
Anes Abdennebi, Erkay Savaş
In this work, we provide GPU-based algorithms for accelerating KP-ABE encryption and homomorphic evaluation functions seamlessly integrated into the open-source library with minor additional build changes needed to run the GPU kernels. Using GPU algorithms, we perform both homomorphic encryption and homomorphic evaluation operations 2.1× and 13.2× faster than the CPU implementations reported in the literature on an Intel i9, respectively. Furthermore, our implementation supports up to 128 attributes for encryption and homomorphic evaluation with fixed and changing access policies. Unlike the reported GPU-based homomorphic operations in the literature, which support only up to 32 attributes and give estimations for a higher number of attributes. We also propose a GPU-based KP-ABE scheme for publish/subscribe messaging applications, in which end-to-end security of the messages is guaranteed. Here, while the exchanged messages are encrypted with as many as 128 attributes by publishers, fewer attributes are needed for homomorphic evaluation. Our fast and memory-efficient GPU implementations of KP-ABE encryption and homomorphic evaluation operations demonstrate that the KP-ABE scheme can be used for practicable publish/subscribe messaging applications.
Chris Orsini, Alessandra Scafuro, Tanner Verber
In recent years, some digital assets are managed solely through the knowledge of cryptographic secrets (e.g., cryptocurrency, encrypted datasets), whose loss results in the permanent loss of the digital asset. Since the security of such systems relies on the assumption that the cryptographic key remains secret, a secret owner Alice cannot simply store a backup copy of such secret on the cloud, since this corresponds to giving away her ownership over the digital assets. Thus Alice must rely on her personal machines to maintain these secrets.
Is it possible to obtain the best of the two worlds, where Alice benefits from the convenience of storing a backup copy of her cryptographic secrets on the cloud such that she can recover them even when she loses her devices and forgets all credentials, while at the same time retaining full ownership of her secrets?
In this paper, we show that this is indeed possible, by revisiting and expanding the concept of Break-glass Encryption pioneered by Scafuro [PKC19].
We provide a secret-recovery mechanism where confidentiality is always guaranteed when Alice has not lost her credentials, even in the presence of a malicious cloud and users ([PKC19] only guarantees that a violation of confidentiality will be {\em detected}, not prevented). Recoverability is achieved in most circumstances.
We design and prove security of a credential-less authentication mechanism, that enables Alice to access her secret, without remembering any credentials. This tool was assumed in [PKC19] but not implemented. We redesign the storage mechanism on the cloud side so that the cloud needs to perform no operations during the storage phase. This is in contrast with [PKC19] where the cloud must re-encrypt the stored file continuously with the help of a secure enclave (regardless of whether a recovery procedure will happen).
Our protocols are proved secure in the Universal Composition framework.
Nan Cheng, Naman Gupta, Aikaterini Mitrokotsa, Hiraku Morita, Kazunari Tozawa
Ma et al. (NDSS 2021) presented a lightweight PDTE protocol with sublinear communication cost with linear round complexity in the size of the input data. This protocol works well in the low latency network such as LAN while its total execution time is unfavourably increased in the WAN setting. In contrast, Tsuchida et al. (ProvSec 2020) constructed a constant round PDTE protocol at the cost of communication complexity, which works well in the WAN setting. Although their construction still requires 25 rounds, it showed a possible direction on how to make constant round PDTE protocols. Ji et al. (IEEE Transactions on Dependable and Secure Computing) presented a simplified PDTE with constant rounds using the function secret sharing (FSS) at the cost of communication complexity.
Our proposed protocol only requires five rounds among the employed three servers executing secret sharing schemes, which is comparable to previously proposed protocols that are based on garbled circuits and homomorphic encryption. To further demonstrate the efficiency of our protocol, we evaluated it using real-world classification datasets. The evaluation results indicate that our protocol provides better concrete performance in the WAN setting that has a large network delay.
Xavier Bonnetain, André Schrottenloher
Typically these attacks use the structure of the mode (stream cipher, MAC or authenticated encryption scheme) to embed a period-finding problem, which can be solved with a dedicated quantum algorithm. The hidden period can be recovered with a few superposition queries (e.g., $O(n)$ for Simon's algorithm), leading to state or key-recovery attacks. However, this strategy breaks down if the period changes at each query, e.g., if it depends on a nonce.
In this paper, we focus on this case and give dedicated state-recovery attacks on the authenticated encryption schemes Rocca, Rocca-S, Tiaoxin-346 and AEGIS-128L. These attacks rely on a procedure to find a Boolean hidden shift with a single superposition query, which overcomes the change of nonce at each query. As they crucially depend on such queries, we stress that they do not break any security claim of the authors, and do not threaten the schemes if the adversary only makes classical queries.
Vitaly Kiryukhin
We carefully detail the resources of the adversary in the related key settings, revisit the proof, and obtain tight security bounds. Let $n$ be the bit length of the hash function state. If the amount of processed data is less than about $2^{n-k}$ blocks, then for HMAC-Streebog-512 and Streebog-K, the only effective method of forgery (or distinguishing) is guessing the $k$-bit secret key or the tag if it is shorter than the key. So, we can speak about ``$k$-bit security'' without specifying the amount of material, if the key length is no longer than half of a state. The bound for HMAC-Streebog-256 is worse and equal to $2^{\frac{n}{2}-k}$ blocks.
Hiroki Okada, Rachel Player, Simon Pohmann
We investigate how to apply our improved polynomial evaluation to the bootstrapping procedure for BFV, and show that we are able to significantly improve its performance. We demonstrate this by providing an implementation of our improved BFV bootstrapping using the Microsoft SEAL library. More concretely, we obtain a $1.6\times$ speed up compared to the prior implementation given by Chen and Han (Eurocrypt 2018). The techniques are independent of, and can be combined with, the more recent optimisations presented by Geelen \textit{et al}. (Eurocrypt 2023).
As an additional contribution, we show how the bootstrapping approach used in schemes such as FHEW and TFHE can be applied in the BFV context. In particular, we demonstrate that programmable bootstrapping can be achieved for BFV. Moreover, we show how this bootstrapping approach can be improved in the BFV context to make better use of the Galois structure. However, we estimate that its complexity is around three orders of magnitude slower than the classical approach to BFV bootstrapping.
Vitaly Kiryukhin
Ling Song, Qianqian Yang, Huimin Liu
Joachim Neu, Ertem Nusret Tas, David Tse
Martin R. Albrecht, Benjamin Dowling, Daniel Jones
Utilising our new formalism, we determine that Matrix achieves the basic security notions of confidentiality and authentication, provided it introduces authenticated group membership. On the other hand, while the state sharing functionality in Matrix conflicts with advanced security notions in the literature – forward and post-compromise security – it enables features such as history sharing and account recovery, provoking broader questions about how such security notions should be conceptualised.