IACR News
Here you can see all recent updates to the IACR webpage. These updates are also available:
20 November 2023
John Bostanci, Luowen Qian, Nicholas Spooner, Henry Yuen
ePrint ReportAs immediate applications, we show how to derive hardness amplification theorems for quantum bit commitment schemes (answering a question of Yan [Yan22]), EFI pairs (answering a question of Brakerski, Canetti, and Qian [BCQ23]), public-key quantum money schemes (answering a question of Aaronson and Christiano [AC13]), and quantum zero-knowledge argument systems. We also derive an XOR lemma [Yao82] for quantum predicates as a corollary.
Kamil Otal
ePrint ReportYen-Ting Kuo, Atsushi Takayasu
ePrint ReportRutchathon Chairattana-Apirom, Stefano Tessaro, Chenzhi Zhu
ePrint ReportOur most efficient constructions rely on the chosen-target CDH assumption, which has been used to prove security of Blind BLS by Boldyreva (PKC '03), and can be seen as blind versions of signatures by Goh and Jarecki (EUROCRYPT '03) and Chevallier-Mames (CRYPTO'05). We also give a less efficient scheme with security based on (plain) CDH which builds on top of a natural pairing-free variant of Rai-Choo (Hanzlik, Loss, and Wagner, EUROCRYPT '23). Our schemes have signing protocols that consist of four (in order to achieve regular unforgeability) or five moves (for strong unforgeability).
The blindness of our schemes is either computational (assuming the hardness of the discrete logarithm problem), or statistical in the random oracle model.
Shiyu Li, Yuan Zhang, Yaqing Song, Fan Wu, Feng Lyu, Kan Yang, Qiang Tang
ePrint ReportIn this paper, we first analyze syndrome-based early epidemic warning systems and formalize two security notions, i.e., symptom confidentiality and frequency confidentiality, according to the inherent security requirements. We propose EpiOracle, a cross-facility early warning scheme for unknown epidemics. EpiOracle ensures that the contents and frequencies of syndromes will not be leaked to any unrelated parties; moreover, our construction uses only a symmetric-key encryption algorithm and cryptographic hash functions (e.g., [CBC]AES and SHA-3), making it highly efficient. We formally prove the security of EpiOracle in the random oracle model. We also implement an EpiOracle prototype and evaluate its performance using a set of real-world symptom lists. The evaluation results demonstrate its practical efficiency.
18 November 2023
Abu Dhabi, United Arab Emirates, 5 March - 8 March 2024
Event CalendarSubmission deadline: 25 November 2023
Notification: 22 December 2023
Abu Dhabi Emirate, United Arab Emirates, 5 March - 8 March 2024
Event CalendarSubmission deadline: 10 December 2023
Notification: 10 January 2024
Abu Dhabi, United Arab Emirates, 5 March - 8 March 2024
Event CalendarSubmission deadline: 15 December 2023
Notification: 10 January 2024
Al Saadiyat Island, United Arab Emirates, 5 March - 8 March 2024
Event CalendarSubmission deadline: 10 December 2023
Notification: 10 January 2024
Max-Planck Institutes in Computer Science
Job PostingA doctoral degree in computer science or related fields and an outstanding research record are required. Successful candidates are expected to build a team and pursue a highly visible research agenda, both independently and in collaboration with other groups.
The institutes are part of a network of over 80 MPIs, Germany’s premier basic-research institutes. MPIs have an established record of world-class, foundational research in the sciences, technology, and the humanities. The institutes offer a unique environment that combines the best aspects of a university department and a research laboratory: Faculty enjoy full academic freedom, lead a team of doctoral students and post-docs, and have the opportunity to teach university courses; at the same time, they enjoy ongoing institutional funding in addition to third-party funds, a technical infrastructure unrivaled for an academic institution, as well as internationally competitive compensation.
We maintain an international and diverse work environment and seek applications from outstanding researchers worldwide. The working language is English; knowledge of the German language is not required for a successful career at the institutes.
MPIs are committed to fostering a diverse, inclusive, and global academic community, and consider qualified applicants for employment without discrimination on the basis of gender, race, disability, ethnic or social origin, or any other legally protected status. We particularly encourage applications from groups that are underrepresented in computer science. We welcome applications from dual-career couples and will do our best to try and accommodate their needs.
The initial tenure-track appointment is for six years. A permanent contract can be awarded upon a successful tenure evalution in the sixth year.
Closing date for applications:
Contact: Qualified candidates should apply using the application portal at https://apply.cis.mpg.de. The review of applications will begin on December 1st, 2023.
More information: https://www.cis.mpg.de/tenure-track-openings-at-max-planck-institutes-in-computer-science/
King's College London; UK
Job PostingThe threat of large-scale, general-purpose quantum computers to existing public-key cryptographic solutions has lead to global efforts to standardise post-quantum cryptography as a replacement. One of the front-runners for problems to base post-quantum cryptography on are hard problems on lattices. On the other hand, lattices have emerged as a central building block for more advanced cryptographic functionalities such as fully-homomorphic encryption and zero-knowledge proof systems.
We are inviting applications for PhD studentships in the cryptography lab at King’s College London. Specifically, we are looking for applicants to work with us in the area of lattice-based cryptography, broadly defined.
The PhD could cover studying the underlying hard mathematical problems, cryptanalysis, constructions or applications of lattice-techniques. This can cover post-quantum aspects of lattice-based cryptography and/or advanced functionalities.
We seek applicants with a background in mathematics and/or computer science or related disciplines.
The applicant would work with
Ngoc Khanh Nguyen
https://dblp.org/pid/75/9806-1.html
ngoc_khanh.nguyen@kcl.ac.uk or
Eamonn W. Postlethwaite
https://dblp.org/pid/218/7300.html
eamonn.postlethwaite@kcl.ac.uk (*) or
Martin Albrecht
https://dblp.uni-trier.de/pid/92/7397.html
martin.albrecht@kcl.ac.uk
and we encourage applicants to reach out to one or more of the above to discuss the position informally before applying. To apply, please go to
https://www.kcl.ac.uk/study/postgraduate-research/areas/computer-science-research-mphil-phd
A first deadline for applications is mid January. These are fully-funded positions covering both (international) fees and maintenance. The latter is at the UKRI rate, see https://www.ukri.org/news/ukri-publishes-stipend-and-postgraduate-research-consultation/
(*live in January, beforehand please reach out to Martin Albrecht to be put in touch.)
Closing date for applications:
Contact:
- Ngoc Khanh Nguyen ngoc_khanh.nguyen@kcl.ac.uk or
- Eamonn W. Postlethwaite eamonn.postlethwaite@kcl.ac.uk (*) or
- Martin Albrecht martin.albrecht@kcl.ac.uk
More information: https://www.kcl.ac.uk/study/postgraduate-research/areas/computer-science-research-mphil-phd
17 November 2023
Marshall Ball, Yevgeniy Dodis, Eli Goldin
ePrint ReportMotivated by this, at Eurocrypt'15 Dodis et al. [21] initiated the question of immunizing backdoored PRGs. A $k$-immunization scheme repeatedly applies a post-processing function to the output of $k$ backdoored PRGs, to render any (unknown) backdoors provably useless. For $k=1$, [21] showed that no deterministic immunization is possible, but then constructed "seeded" $1$-immunizer either in the random oracle model, or under strong non-falsifiable assumptions. As our first result, we show that no seeded $1$-immunization scheme can be black-box reduced to any efficiently falsifiable assumption.
This motivates studying $k$-immunizers for $k\ge 2$, which have an additional advantage of being deterministic (i.e., "seedless"). Indeed, prior work at CCS'17 [37] and CRYPTO'18 [7] gave supporting evidence that simple $k$-immunizers might exist, albeit in slightly different settings. Unfortunately, we show that simple standard model proposals of [37, 7] (including the XOR function [7]) provably do not work in our setting. On a positive, we confirm the intuition of [37] that a (seedless) random oracle is a provably secure $2$-immunizer. On a negative, no (seedless) $2$-immunization scheme can be black-box reduced to any efficiently falsifiable assumption, at least for a large class of natural $2$-immunizers which includes all "cryptographic hash functions."
In summary, our results show that $k$-immunizers occupy a peculiar place in the cryptographic world. While they likely exist, and can be made practical and efficient, it is unlikely one can reduce their security to a "clean" standard-model assumption.
Jelle Vos, Mauro Conti, Zekeriya Erkin
ePrint ReportHanlin Zhang, Benjamin L. Edelman, Danilo Francati, Daniele Venturi, Giuseppe Ateniese, Boaz Barak
ePrint ReportShiyu Li, Yuan Zhang, Yaqing Song, Hongbo Liu, Nan Cheng, Hongwei Li, Dahai Tao, Kan Yang
ePrint ReportIn this paper, we formally define the fairness requirement for mailmen-assisted timed data delivery and propose a practical scheme, dubbed DataUber, to achieve fairness. DataUber ensures that honest mailmen receive the service charge, lazy mailmen do not receive the service charge, and malicious mailmen are punished. Specifically, DataUber consists of two key techniques: 1) a new cryptographic primitive, i.e., Oblivious and Verifiable Threshold Secret Sharing (OVTSS), enabling a dealer to distribute a secret among multiple participants in a threshold and verifiable way without knowing any one of the shares, and 2) a smart-contract-based complaint mechanism, allowing anyone to become a reporter to complain about a mailman's misbehavior to a smart contract and receive a reward. Furthermore, we formally prove the security of DataUber and demonstrate its practicality through a prototype implementation.
Uddipana Dowerah, Aikaterini Mitrokotsa
ePrint ReportHanwen Feng, Tiancheng Mai, Qiang Tang
ePrint ReportOur DKG leads to a fully practical instantiation of Filecoin's checkpointing mechanism, in which all validators of a Proof-of-Stake (PoS) blockcahin periodically run DKG and threshold signing to create checkpoints on Bitcoin, thereby enhancing the security of the PoS chain. In comparison with another checkpointing approach of Babylon (Oakland, 2023), ours enjoys a significally smaller monetary cost of Bitcoin transaction fees. For a PoS chain with $2^{12}$ validators, our cost is merely 0.6% of that incurred by Babylon's approach.
Taiga Hiroka, Fuyuki Kitagawa, Ryo Nishimaki, Takashi Yamakawa
ePrint ReportAlthough robust combiners and universal constructions for classical cryptography are widely studied, robust combiners and universal constructions for quantum cryptography have not been explored so far. In this work, we define robust combiners and universal constructions for several quantum cryptographic primitives including one-way state generators, public-key quantum money, quantum bit commitments, and unclonable encryption, and provide constructions of them.
On a different note, it was an open problem how to expand the plaintext length of unclonable encryption. In one of our universal constructions for unclonable encryption, we can expand the plaintext length, which resolves the open problem.