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kutasp89.bsky.social
@kutasp89.bsky.social
44 followers 38 following 10 posts
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tiborj.bsky.social
The call for papers for PKC 2026 is out: pkc.iacr.org/2026/callfor...
PKC 2026 call for papers
Public Key Cryptography
pkc.iacr.org
September 25, 2025 at 5:53 PM
Reposted
eprint.ing.bot
Bribers, Bribers on The Chain, Is Resisting All in Vain? Trustless Consensus Manipulation Through Bribing Contracts (Bence Soóki-Tóth, István András Seres, Kamilla Kara, Ábel Nagy, Balázs Pejó, Gergely Biczók) ia.cr/2025/1719
Abstract. The long-term success of cryptocurrencies largely depends on the incentive compatibility provided to the validators. Bribery attacks, facilitated trustlessly via smart contracts, threaten this foundation. This work introduces, implements, and evaluates three novel and efficient bribery contracts targeting Ethereum validators. The first bribery contract enables a briber to fork the blockchain by buying votes on their proposed blocks. The second contract incentivizes validators to voluntarily exit the consensus protocol, thus increasing the adversary’s relative staking power. The third contract builds a trustless bribery market that enables the briber to auction off their manipulative power over the RANDAO, Ethereum’s distributed randomness beacon. Finally, we provide an initial game-theoretical analysis of one of the described bribery markets.
September 22, 2025 at 12:46 AM
Reposted
maria.isogeny.club
TL;DR: we solve norm equations in a better way and get around a 2x improvement to IdealToIsogeny routines crucial in both SQIsign and PRISM.
eprint.ing.bot ePrint Updates @eprint.ing.bot · Sep 11
Qlapoti: Simple and Efficient Translation of Quaternion Ideals to Isogenies (Giacomo Borin, Maria Corte-Real Santos, Jonathan Komada Eriksen, Riccardo Invernizzi, Marzio Mula, Sina Schaeffler, Frederik Vercauteren) ia.cr/2025/1604
Abstract. The main building block in isogeny-based cryptography is an algorithmic version of the Deuring correspondence, called IdealToIsogeny. This algorithm takes as input left ideals of the endomorphism ring of a supersingular elliptic curve and computes the associated isogeny. Building on ideas from QFESTA, the Clapoti framework by Page and Robert reduces this problem to solving a certain norm equation. The current state of the art is however unable to efficiently solve this equation, and resorts to a relaxed version of it instead. This impacts not only the efficiency of the IdealToIsogeny procedure, but also its success probability. The latter issue has to be mitigated with complex and memory-heavy rerandomization procedures, but still leaves a gap between the security analysis and the actual implementation of cryptographic schemes employing IdealToIsogeny as a subroutine. For instance, in SQIsign the failure probability is still 2⁻⁶⁰ which is not cryptographically negligible. The main contribution of this paper is a very simple and efficient algorithm called Qlapoti which approaches the norm equation from Clapoti directly, solving all the aforementioned problems at once. First, it makes the IdealToIsogeny subroutine between 2.2 and 2.6 times faster. This signigicantly improves the speed of schemes using this subroutine, including notably SQIsign and . On top of that, Qlapoti has a cryptographically negligible failure probability. This eliminates the need for rerandomization, drastically reducing memory consumption, and allows for cleaner security reductions. Image showing part 2 of abstract.
September 12, 2025 at 2:00 PM
Reposted
eprint.ing.bot
Qlapoti: Simple and Efficient Translation of Quaternion Ideals to Isogenies (Giacomo Borin, Maria Corte-Real Santos, Jonathan Komada Eriksen, Riccardo Invernizzi, Marzio Mula, Sina Schaeffler, Frederik Vercauteren) ia.cr/2025/1604
Abstract. The main building block in isogeny-based cryptography is an algorithmic version of the Deuring correspondence, called IdealToIsogeny. This algorithm takes as input left ideals of the endomorphism ring of a supersingular elliptic curve and computes the associated isogeny. Building on ideas from QFESTA, the Clapoti framework by Page and Robert reduces this problem to solving a certain norm equation. The current state of the art is however unable to efficiently solve this equation, and resorts to a relaxed version of it instead. This impacts not only the efficiency of the IdealToIsogeny procedure, but also its success probability. The latter issue has to be mitigated with complex and memory-heavy rerandomization procedures, but still leaves a gap between the security analysis and the actual implementation of cryptographic schemes employing IdealToIsogeny as a subroutine. For instance, in SQIsign the failure probability is still 2⁻⁶⁰ which is not cryptographically negligible. The main contribution of this paper is a very simple and efficient algorithm called Qlapoti which approaches the norm equation from Clapoti directly, solving all the aforementioned problems at once. First, it makes the IdealToIsogeny subroutine between 2.2 and 2.6 times faster. This signigicantly improves the speed of schemes using this subroutine, including notably SQIsign and . On top of that, Qlapoti has a cryptographically negligible failure probability. This eliminates the need for rerandomization, drastically reducing memory consumption, and allows for cleaner security reductions. Image showing part 2 of abstract.
September 11, 2025 at 4:14 PM
kutasp89.bsky.social
Can someone provide me with an explanation how TCHES ended up on some Norwegian list for predatory journals?
September 3, 2025 at 3:30 PM
Reposted
cosic.bsky.social
Proud moment at #CRYPTO 2025!
“KLPT²: Algebraic Pathfinding in Dimension Two and Applications” received the Best Paper Award. 🏆
Co-authored by COSIC’s Wouter Castryck & Thomas Decru (presenter).
Read it here: eprint.iacr.org/2025/372
August 21, 2025 at 1:37 PM
kutasp89.bsky.social
Very sad news
July 31, 2025 at 11:38 AM
Reposted
janne.hamalainen.social
This exactly. And it's not just theoretical, it can happen for real. "The Chinese state-sponsored cyberattack threat managed to infiltrate the "lawful intercept" network connections that police use in criminal investigations." www.darkreading.com/cyber-risk/s...
Sat Typhoon APT Subverts Law Enforcement Wiretapping
The Chinese state-sponsored cyberattack threat managed to infiltrate the "lawful intercept" network connections that police use in criminal investigations.
www.darkreading.com
July 6, 2025 at 1:52 PM
Reposted
krijn.isogeni.es
Yessss!!!
cosic.bsky.social COSIC @cosic.bsky.social · Jun 16
Registration for the Leuven Isogeny Days 6 is now open!
📅 10–12 Sept 2025 @ KU Leuven
Morning: research talks
Afternoon: brainstorming sessions
More info: www.esat.kuleuven.be/cosic/projec...
#isogeny #isocrypt #erc #postquantum
June 16, 2025 at 9:48 AM
Reposted
davidpicard.bsky.social
Reminder that the MSCA postdoctoral program exists. If you have a PhD and want to work in a European lab, you have until September to apply. Just contact them now.

ec.europa.eu/info/funding...
ec.europa.eu
June 6, 2025 at 5:47 PM
Reposted
eprint.ing.bot
Orient Express: Using Frobenius to Express Oriented Isogenies (Wouter Castryck, Riccardo Invernizzi, Gioella Lorenzon, Jonas Meers, Frederik Vercauteren) ia.cr/2025/1047
Abstract. In this paper we study supersingular elliptic curves primitively oriented by an imaginary quadratic order, where the orientation is determined by an endomorphism that factors through the Frobenius isogeny. In this way, we partly recycle one of the main features of CSIDH, namely the fact that the Frobenius orientation can be represented for free. This leads to the most efficient family of ideal-class group actions in a range where the discriminant is significantly larger than the field characteristic p. Moreover, if we orient with a non-maximal order $\mathcal{O} \subset \mathbb{Q}(\sqrt{-p})$ and we assume that it is feasible to compute the ideal-class group of the maximal order, then also the ideal-class group of 𝒪 is known and we recover the central feature of SCALLOP-like constructions. We propose two variants of our scheme. In the first one, the orientation is by a suborder of the form $\mathbb{Z}[f\sqrt{-p}]$ for some f coprime to p, so this is similar to SCALLOP. In the second one, inspired by the work of Chenu and Smith, the orientation is by an order of the form $\mathbb{Z}[\sqrt{-dp}]$ where d is square-free and not a multiple of p. We give practical ways of generating parameters, together with a proof-of-concept SageMath implementation of both variants, which shows the effectiveness of our construction. Image showing part 2 of abstract.
June 5, 2025 at 4:37 PM
Reposted
andreavbasso.bsky.social
Next week @lucianomaino.bsky.social and I will teach a week-long course on SQIsign at the University of Trento.

The course will be both in-person and online: if you're interested, you can tune in Monday morning at 10:30 at unitn.zoom.us/j/88902079708

(details and full schedule in the image below)
Title of the PhD course: Advances in Cryptography and Codes - Part 1: SQIsign Lecturers: Andrea Basso (IBM Research Zurich, CH), Luciano Maino (University of Bristol, UK) The course in short: The course offers a comprehensive and rigorous introduction to SQIsign, an advanced isogeny-based digital signature scheme designed to resist attacks from quantum computers. The course will present the mathematical foundations on which SQIsign is based and the algorithmic background necessary to understand and evaluate the security of SQIsign and other isogeny-based protocols. Complementing the theoretical material, the course also includes a practical laboratory where students will use SageMath to study and implement various aspects of SQIsign. Where (in presence): Department of Mathematics, University of Trento (IT) Via Sommarive, 5, 38123, Trento (online): https://unitn.zoom.us/j/88902079708 (Passcode: 532383) When: From May 19, 2025 to May 28, 2025 Detailed Program: Monday 19/05 10:30 - 12:30 (Room A205) & 14:30 - 16:30 (Room A221) Tuesday 20/05 10:30 - 12:30 (Room A215) & 14:30 - 16:30 (Room A213) Wednesday 21/05 10:30 - 12:30 (Room A218) & 14:30 - 16:30 (Room A215) Thursday 22/05 10:30 - 12:30 (Room A209) & 14:30 - 16:30 (Room A220) Friday 23/05 10:30 - 12:30 (Room A215) & 14:30 - 16:30 (Room A215) Tuesday 27/05 11:30 - 12:30 – Q&A, optional (Room A218) Wednesday 28/05 11:30 - 12:30 – Q&A, optional (Room A218)
May 17, 2025 at 1:42 PM
kutasp89.bsky.social
CECC 2025 will accept posters, submission deadline is the 23rd May (more details can be found at cecc2025.inf.elte.hu). Also we have great invited speakers (Carla Rafols, Thomas Decru, Stefan Dziembowski), so hope to see you in Budapest!
Central European Conference on Cryptology 2025
Central European Conference on Cryptology 2025
cecc2025.inf.elte.hu
May 10, 2025 at 7:04 PM
Reposted
malb.bsky.social
This is cool heimberger.xyz/oprfs.html
PQ-OPRF table
heimberger.xyz
May 8, 2025 at 7:52 AM
Reposted
bsky.defeo.lu
The SQIparty starts on Monday, but it's still time to register!

We prepared an exciting program for you with a balanced mix of talks, coding sprints, skillshares and other activities!

www.cig.udl.cat/SQIparty2025...

See you in Lleida!
bsky.defeo.lu Luca De Feo @bsky.defeo.lu · Mar 13
Fancy some isogeny crypto?

Join us for a 3-day workshop on isogeny-based cryptography in Lleida, Catalonia, April 28-30

www.cig.udl.cat/icrypto2025_...

Brought to you by ULleida's Cryptography+Graphs group, the SQIsign team and friends!

Registration and program coming soon
Registration is free!
Cathedral of La Seu Vella in Lleida
April 25, 2025 at 2:14 PM
Reposted
krijn.isogeni.es
New work: we explain cubical arithmetic in simple terms to show you how easy it is to compute pairings. Essentially, you only need to know the Montgomery ladder!

As a bonus, pairings from cubical arithmetic are faster than those from Miller's loop for applications in isogeny-based cryptography.
eprint.ing.bot ePrint Updates @eprint.ing.bot · Apr 15
Simpler and Faster Pairings from the Montgomery Ladder (Giacomo Pope, Krijn Reijnders, Damien Robert, Alessandro Sferlazza, Benjamin Smith) ia.cr/2025/672
Abstract. We show that Montgomery ladders compute pairings as a by-product, and explain how a small adjustment to the ladder results in simple and efficient algorithms for the Weil and Tate pairing on elliptic curves using cubical arithmetic. We demonstrate the efficiency of the resulting cubical pairings in several applications from isogeny-based cryptography. Cubical pairings are simpler and more performant than pairings computed using Miller’s algorithm: we get a speed-up of over 40% for use-cases in SQIsign, and a speed-up of about 7% for use-cases in CSIDH. While these results arise from a deep connection to biextensions and cubical arithmetic, in this article we keep things as concrete (and digestible) as possible. We provide a concise and complete introduction to cubical arithmetic as an appendix.
April 15, 2025 at 12:34 PM
Reposted
maria.isogeny.club
Really excited to share the Decrypting Diversity Summit happening in Montpellier, France from 17-20 June! The goal of the summit is to promote diversity, inclusivity, and gender equality within the cryptography community. For more info: decryptingdiversity.com
Decrypting Diversity Summit
Decrypting Diversity Summit
decryptingdiversity.com
April 3, 2025 at 12:11 PM
kutasp89.bsky.social
Deadline to submit to this conference is today!
bsky.defeo.lu Luca De Feo @bsky.defeo.lu · Feb 13
Our friends at ELTE are organizing the Central European Crypology conference (CECC 2025) in Budapest and they're looking forward to your submissions (you only need to submit an extended abstract). Every info on the webpage: cecc2025.inf.elte.hu/en/
Central European Conference on Cryptology 2025
Central European Conference on Cryptology 2025
cecc2025.inf.elte.hu
March 31, 2025 at 9:49 AM
Reposted
rwc.iacr.org
The second Levchin Prize goes to the CADO-NFS team: Emmanuel Thomé, Pierrick Gaudry, and Paul Zimmerman! Congratulations!

#realworldcrypto
March 26, 2025 at 9:24 AM
Reposted
andreavbasso.bsky.social
Registration is now open! www.cig.udl.cat/SQIparty2025...
andreavbasso.bsky.social Andrea Basso @andreavbasso.bsky.social · Mar 13
This workshop is gonna be great: cool people, interesting talks, and lots of great research on SQIsign and isogeny-based crypto. Mark it in your calendars!

And if you’re going to Eurocrypt, this is going to be convenient: the workshop is just the week before, and it’s not too far from Madrid
bsky.defeo.lu Luca De Feo @bsky.defeo.lu · Mar 13
Fancy some isogeny crypto?

Join us for a 3-day workshop on isogeny-based cryptography in Lleida, Catalonia, April 28-30

www.cig.udl.cat/icrypto2025_...

Brought to you by ULleida's Cryptography+Graphs group, the SQIsign team and friends!

Registration and program coming soon
Registration is free!
March 24, 2025 at 9:14 AM
Reposted
bsky.defeo.lu
Fancy some isogeny crypto?

Join us for a 3-day workshop on isogeny-based cryptography in Lleida, Catalonia, April 28-30

www.cig.udl.cat/icrypto2025_...

Brought to you by ULleida's Cryptography+Graphs group, the SQIsign team and friends!

Registration and program coming soon
Registration is free!
Cathedral of La Seu Vella in Lleida
March 13, 2025 at 5:30 PM
Reposted
maria.isogeny.club
Next week (Tuesday 5pm CET) at The Isogeny Club we'll have Laurane Marco (EPFL) who will talk to us about computing modular polynomials modulo a generic prime! More details at isogeny.club
The Isogeny Club
isogeny.club
March 6, 2025 at 12:58 PM
Reposted
eprint.ing.bot
On the Soundness of Algebraic Attacks against Code-based Assumptions (Miguel Cueto Noval, Simon-Philipp Merz, Patrick Stählin, Akin Ünal) ia.cr/2025/415
Abstract. We study recent algebraic attacks (Briaud-Øygarden EC’23) on the Regular Syndrome Decoding (RSD) problem and the assumptions underlying the correctness of their attacks’ complexity estimates. By relating these assumptions to interesting algebraic-combinatorial problems, we prove that they do not hold in full generality. However, we show that they are (asymptotically) true for most parameter sets, supporting the soundness of algebraic attacks on RSD. Further, we prove—without any heuristics or assumptions—that RSD can be broken in polynomial time whenever the number of error blocks times the square of the size of error blocks is larger than 2 times the square of the dimension of the code. Additionally, we use our methodology to attack a variant of the Learning With Errors problem where each error term lies in a fixed set of constant size. We prove that this problem can be broken in polynomial time, given a sufficient number of samples. This result improves on the seminal work by Arora and Ge (ICALP’11), as the attack’s time complexity is independent of the LWE modulus. Image showing part 2 of abstract.
March 5, 2025 at 3:55 PM
Reposted
borisfouotsa.bsky.social
16th International Conference on Cryptology AFRICACRYPT 2025
July 21-23, 2025 – Rabat, Morocco 🇲🇦

Extended submission deadline in 1 week:
africacrypt2025.sciencesconf.org
Submit your best results !

See you in Rabat 🇲🇦 in July 2025.
16th International Conference on Cryptology, Africacrypt 2025 - Sciencesconf.org
Africacrypt 2025 is organized by the ENSIAS College of Mohammed V University in Rabat with partnership of the General Directorate of Information Systems Security (DGSSI), Morocco.
africacrypt2025.sciencesconf.org
March 3, 2025 at 1:49 PM
Reposted
eprint.ing.bot
PEGASIS: Practical Effective Class Group Action using 4-Dimensional Isogenies (Pierrick Dartois, Jonathan Komada Eriksen, Tako Boris Fouotsa, Arthur Herlédan Le Merdy, Riccardo Invernizzi, Damien Robert, Ryan Rueger, Frederik Vercauteren, Benjamin Wesolowski) ia.cr/2025/401
Abstract. In this paper, we present the first practical algorithm to compute an effective group action of the class group of any imaginary quadratic order 𝒪 on a set of supersingular elliptic curves primitively oriented by 𝒪. Effective means that we can act with any element of the class group directly, and are not restricted to acting by products of ideals of small norm, as for instance in CSIDH. Such restricted effective group actions often hamper cryptographic constructions, e.g. in signature or MPC protocols. Our algorithm is a refinement of the Clapoti approach by Page and Robert, and uses 4-dimensional isogenies. As such, it runs in polynomial time, does not require the computation of the structure of the class group, nor expensive lattice reductions, and our refinements allows it to be instantiated with the orientation given by the Frobenius endomorphism. This makes the algorithm practical even at security levels as high as CSIDH-4096. Our implementation in SageMath takes 1.5s to compute a group action at the CSIDH-512 security level, 21s at CSIDH-2048 level and around 2 minutes at the CSIDH-4096 level. This marks the first instantiation of an effective cryptographic group action at such high security levels. For comparison, the recent KLaPoTi approach requires around 200s at the CSIDH-512 level in SageMath and 2.5s in Rust. Image showing part 2 of abstract.
March 4, 2025 at 8:20 AM