IACR News
Here you can see all recent updates to the IACR webpage. These updates are also available:
30 December 2021
Nariyasu Heseri, Koji Nuida
Rawane Issa, Nicolas AlHaddad, Mayank Varia
In this work, we provide a new construction for asymmetric message franking called Hecate that is faster, more secure, and introduces additional functionality compared to Tyagi et al. First, our construction uses fewer invocations of standardized crypto primitives and operates in the plain model. Second, on top of AMF’s accountability and deniability requirements, we also add forward and backward secrecy. Third, we combine AMF with source tracing, another approach to content moderation that has previously been considered only in the setting of non-anonymous networks. Source tracing allows for messages to be forwarded, and a report only identifies the original source who created a message. To provide anonymity for senders and forwarders, we introduce a model of "AMF with preprocessing" whereby every client authenticates with the moderator out-of-band to receive a token that they later consume when sending a message anonymously.
Virtual event, Anywhere on Earth, 9 May - 11 May 2022
Submission deadline: 20 March 2022
Notification: 1 April 2022
Villanova University, Department of ECE, Villanova, PA, USA
Villanova University ranks #49 National Universities in the USA, is located in Villanova, Pennsylvania (west suburban of Philadelphia). Famous alumni include the current First Lady of the USA!
Requirements: Preferred to be in majors of EE/CE/CS, Applied Mathematics/Cryptography related majors are also warmly welcome!
Proficiency in English both speaking and writing abilities.
Skillful in programming Languages such as VHDL/Verilog, CC++, Python, and so on (FPGA-based experience is also desirable). Great enthusiasm for doing research-oriented tasks. Excellent teamwork member.
Degree: both BS and MS graduates or similar are warmly welcomed to apply.
Deadline: better to start in Summer/Fall 2022. It is always better to apply as early as possible. The position is open until it is filled.
Our lab atmosphere is peaceful and harmonious. Advisor and senior Ph.D. student will guide you to get started and work together on forthcoming challenges. You will not be fighting alone (emphasize this important thing three times!!!).
Email: jiafeng.xie@villanova.edu
This research focuses on the hardware-accelerated implementation of the combination of post-quantum cryptography and AI security (Fully Homomorphic Encryption). This direction is very new and looks promising for the next 5-n years, so a lot of research will be happening. At the same time, more opportunities are coming up, i.e., it is easier to find your development after exploring the combined research of post-quantum cryptography and AI. If you are interested, please email Dr. Xie.
Lastly, if you feel interested, please email: jiafeng.xie@villanova.edu and discuss your ideas.
Closing date for applications:
Contact: Dr. Jiafeng Harvest Xie
More information: https://www.ece.villanova.edu/~jxie02/lab/
27 December 2021
University of California, Santa Cruz (CSE Dept.)
The Computer Science and Engineering Department of the University of California, Santa Cruz invites applications for PhD students and Post-doctoral fellows in the topics of (applied) cryptography, security and privacy, secure databases and systems. Applicants should have a background/interest in cryptography, searchable encryption, databases and systems, oblivious RAM and oblivious computation, secure multi-party computation, hardware enclaves, computer & cloud security.
Closing Date for Application: January 10, 2022
Closing date for applications:
Contact: Assistant Prof. Ioannis Demertzis, idemertz (at) ucsc.edu
More information: http://idemertzis.com/UCSC_PHD_Postdoc_Openings.pdf
Spring Labs; Marina del Rey, Los Angeles, California
This role is responsible for design and specification of next-generation systems leveraging partial, somewhat, and fully homomorphic encryption. You will interact closely with Software Engineering and Product teams to ensure our newest products are effective, usable, performant and scalable.
Although Spring Labs has an in-office culture fostering a highly creative and collaborative environment, full-remote is acceptable for this role for the right candidate.
If you are motivated by solving real-world problems and want to work alongside veteran cryptographers and world-class engineers, we want to hear from you.
What you'll do- Design secure, novel, performant systems using cutting edge cryptography
- Author specifications, patents and papers detailing the systems and techniques that will underpin our next generation of products
- Communicate complex designs to engineers and support them in the implementation
- Educate technical and non-technical stakeholders on our tools and technologies
- Ph.D. – Cryptography, Math, Computer Science, Engineering or related discipline
- Strong background in design and evaluation of cryptographic primitives and protocols
- Preferably-extensive experience in homomorphic encryption schemes and underlying structures such as lattices, and their optimizations
- Robust interest in pursuing research/architecture of systems-level applications of cryptography pertaining to practical utilization of homomorphic encryption, oblivious transfer, secure multiparty computation, proxy re-encryption, privacy-preserving entity resolution, private information retrieval, private function evaluation, and functional encryption
- Genuine desire to maximize team output, e.g., exercise an established capability to cryptanalyze contributions of others
- Ability to implement prototypes and working knowledge of cryptographic libraries a plus
Closing date for applications:
Contact: David W. Kravitz, Director of Research, david@springlabs.com
Katie Thompson, Director of Human Resources, katiet@springlabs.com
More information: https://jobs.lever.co/springlabs/35c6327f-1ef9-47a8-b08c-3e79c45e2c23
23 December 2021
Washington, USA, 27 June - 30 June 2022
Submission deadline: 15 January 2022
Notification: 15 February 2022
Aalto University & Helsinki University, Department of Computer Science, Espoo/Helsinki, Finland
We offer the possibility to participate and take initiative in leading-edge research in a young and growing research environment with 10 professors and their teams working on foundational topics in the Helsinki area at Aalto University and the University of Helsinki (*). The postdoctoral researcher positions are full-time research positions for a duration of one year, with the possibility of extension to a second year by mutual consent. Travel funding is available for travel permitted by the pandemic situation. Participation in teaching of advanced courses and thesis instruction is possible and encouraged, with 5-10% allocation of the total working time.
(*) https://research.cs.aalto.fi/theory/
Supervisors:
Closing date for applications:
Contact:
More information: https://www.hiit.fi/open-calls/
22 December 2021
Debajyoti Das, Sebastian Meiser, Esfandiar Mohammadi, Aniket Kate
We demonstrate Streams' performance through a prototype implementation. Our results show that Streams can scale well even if the system has a load of one million messages at any point in time. Streams maintains a latency of $16$ seconds while offering provable ``one-in-a-billion'' unlinkability, and can be leveraged for applications such as anonymous microblogging and network-level anonymity for blockchains. We also illustrate by examples that our scaling technique can be useful to many other AC protocols to improve their scalability and privacy, and can be interesting to protocol developers.
Li Yao, Yilei Chen, Yu Yu
In this paper, we show cryptanalytic attacks on the iO candidate provided by Bartusek et al. Our attack exploits the weakness of one of the randomization steps in the candidate. The attack applies to a fairly general class of programs. At the end of the paper we discuss plausible countermeasures to defend against our attacks.
Valerie Fetzer, Marcel Keller, Sven Maier, Markus Raiber, Andy Rupp, Rebecca Schwerdt
In PUBA, users keep an unlinkable but authenticated cryptographic logbook containing their historic data on their device. This logbook can only be updated by the operator while its content is not revealed. Users can take part in a privacy-preserving analytics computation, where it is ensured that their logbook is up-to-date and authentic while the potentially secret analytics function is verified to be privacy-friendly. Taking constrained devices into account, users may also outsource analytic computations (to a potentially malicious proxy not colluding with the operator).
We model our novel building block in the Universal Composability framework and provide a practical protocol instantiation. To demonstrate the flexibility of PUBA, we sketch instantiations of privacy-preserving fraud detection and targeted advertising, although it could be used in many more scenarios, e.g. data analytics for multi-modal transportation systems. We implemented our bookkeeping protocols and an exemplary outsourced analytics computation based on logistic regression using the MP-SPDZ MPC framework. Performance evaluations using a smartphone as user device and more powerful hardware for operator and proxy suggest that PUBA for smaller logbooks can indeed be practical.
Yi Liu, Qi Wang, Siu-Ming Yiu
In this paper, we revisit the two-party PFE problem and provide several enhancements. We propose the \emph{first} constant-round actively secure PFE protocol with linear complexity. Based on this result, we further provide the \emph{first} constant-round publicly verifiable covertly (PVC) secure PFE protocol with linear complexity to gain better efficiency. For instance, when the deterrence factor is $\epsilon = 1/2$, compared to the passively secure protocol, its communication cost is very close and its computation cost is around $2.6\times$. In our constructions, as a by-product, we design a specific protocol for proving that a list of ElGamal ciphertexts is derived from an \emph{extended permutation} performed on a given list of elements. It should be noted that this protocol greatly improves the previous result and may be of independent interest. In addition, a reusability property is added to our two PFE protocols. Namely, if the same function $f$ is involved in multiple executions of the protocol between $P_A$ and $P_B$, then the protocol could be executed more efficiently from the second execution. Moreover, we further extend this property to be \emph{global}, such that it supports multiple executions for the same $f$ in a reusable fashion between $P_A$ and \emph{arbitrary} parties playing the role of $P_B$.
Pierrick Dartois, Luca De Feo
In this work we revisit the security of OSIDH by presenting a new attack, building upon previous work of Onuki. Our attack has exponential complexity, but it practically breaks Colò and Kohel's parameters unlike Onuki's attack. We also discuss countermeasures to our attack, and analyze their impact on OSIDH, both from an efficiency and a functionality point of view.
Aisling Connolly, Pascal Lafourcade, Octavio Perez Kempner
In this work, we additionally consider equivalence classes on the signing-key space. In this regard, we obtain a signer-hiding notion, where the issuing organization is not revealed when a user shows a credential. To achieve this, we instantiate the ABC framework of Fuchsbauer, Hanser, and Slamanig (FHS, Journal of Cryptology '19) with a recent SPS-EQ scheme (ASIACRYPT '19) modified to support a fully adaptive NIZK from the framework of Couteau and Hartmann (CRYPTO '20). We also show how to obtain Mercurial Signatures (CT-RSA, 2019), extending the application of our construction to anonymous delegatable credentials.
To further increase functionality and efficiency, we augment the set-commitment scheme of FHS19 to support openings on attribute sets disjoint from those possessed by the user, while integrating a proof of exponentiation to allow for a more efficient verifier. Instantiating in the CRS model, we obtain an efficient credential system, anonymous under malicious organization keys, with increased expressiveness and privacy, proven secure in the standard model.
Jiaxin Guan, Daniel Wichs, Mark Zhandry
In this work, we give simple constructions of both incompressible public-key encryption and signatures under minimal assumptions. Furthermore, large incompressible ciphertexts (resp. signatures) can be decrypted (resp. verified) in a streaming manner with low storage. In particular, these notions strengthen the related concepts of disappearing encryption and signatures, recently introduced by Guan and Zhandry (TCC 2021), whose previous constructions relied on sophisticated techniques and strong, non-standard assumptions. We extend our constructions to achieve an optimal ``rate'', meaning the large ciphertexts (resp. signatures) can contain almost equally large messages, at the cost of stronger assumptions.
21 December 2021
Budapest, Hungary, 1 August - 5 August 2022
Zero-Knowledge for Homomorphic Key-Value Commitments with Applications to Privacy-Preserving Ledgers
Matteo Campanelli, Felix Engelmann, Claudio Orlandi
John Baena, Pierre Briaud, Daniel Cabarcas, Ray Perlner, Daniel Smith-Tone, Javier Verbel
George Teseleanu
Sarasij Maitra, David J. Wu
In this work, we study traceable pseudorandom functions (PRFs). As PRFs are the workhorses of symmetric cryptography, traceable PRFs are useful for augmenting symmetric cryptographic primitives with strong traceable security guarantees. However, existing constructions of traceable PRFs either rely on strong notions like indistinguishability obfuscation or satisfy weak security guarantees like single-key security (i.e., tracing only works against adversaries that possess a single marked key).
In this work, we show how to use fingerprinting codes to upgrade a single-key traceable PRF into a fully collusion resistant traceable PRF, where security holds regardless of how many keys the adversary possesses. We additionally introduce a stronger notion of security where tracing security holds even against active adversaries that have oracle access to the tracing algorithm. In conjunction with known constructions of single-key traceable PRFs, we obtain the first fully collusion resistant traceable PRF from standard lattice assumptions. Our traceable PRFs directly imply new lattice-based secret-key traitor tracing schemes that are CCA-secure and where tracing security holds against active adversaries that have access to the tracing oracle.