iiinova — where your digital self keeps evolving

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Maria Corte-Real Santos @maria.isogeny.club · 03/09/2026

Rise and shine, it's time for the Isogeny Club Season Nine! isogeny.club

isogeny.club

The Isogeny Club

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Deirdre Connolly¹ ² @durumcrustulum.com · 01/09/2026

SQIsign has been updated for Round 3 of the NIST PQC signatures on-ramp: - updated params re: eprint 2026/1486 - new full fixed-precision arithmetic with tight size bounds - no more floating point in lattice reduction - new ideal-to-isogeny, gluing algs, speedups sqisign.org/spec/sqisign...

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COSIC @cosic.bsky.social · 17/08/2026

We’re excited to announce the 7th edition of the Leuven Isogeny Days (Sept 16–18, 2026)! Registration is open until 22 August, join us! More info & signup: www.esat.kuleuven.be/cosic/projec... #LID #Isogeny #IsogenyDays

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ePrint Updates @eprint.ing.bot · 03/08/2026

Solving the supersingular isogeny problem in time p^(2/5 + o(1)) using bivariate multipoint evaluation (Aleksei Udovenko) ia.cr/2026/1575

Abstract. This note presents a new unconditional attack on the supersingular isogeny problem, with time and memory complexity p^(2/5 + o(1)). It builds on the approach by Eisenträger-Hallgren-Leonardi-Morrison-Park (2020) and Fuselier-Iezzi-Kozek-Morrison-Namoijam (2025), and is related to the recent heuristic attack with complexity p^(1/3 + o(1)) by Wesolowski (ePrint 2026/1486): all of these search for a separable isogeny from a curve to its Galois conjugate to form a non-scalar endomorphism.

Our attack is based on highly theoretical multivariate multipoint evaluation algorithms from Kedlaya-Umans (2008, 2011), Bhargava-Ghosh-Guo-Kumar-Umans (2022), and Ghosh-Harsha-Herdade-Kumar-Saptharishi (2023), and therefore does not threaten isogeny cryptosystems in practice; it is of theoretical interest.

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ePrint Updates @eprint.ing.bot · 21/07/2026

Identity-Based Encryption from Isogenies (Shweta Agrawal, Andrea Basso, Sikhar Patranabis) ia.cr/2026/1457

Abstract. We provide the first construction of identity-based encryption from isogeny-based assumptions. Security of our construction relies on a novel assumption called the “CDH with Mismatched Torsion” (CD-HwMT) assumption, which we introduce. At a high level, the assumption posits the hardness of solving a CDH-like problem even when the adversary is given some additional “safe” leakage. We justify our assumption by showing that, in the Algebraic Isogeny Model, our assumption reduces to well-known assumptions from the literature.

As a bonus feature, our identity-based encryption enjoys anonymity, which means that the ciphertexts hide not only the message but also the target identity. We additionally obtain the first isogeny based constructions of laconic oblivious transfer, as well as public-key encryption that simultaneously satisfies security against high-rate key leakage and key-dependent message/circular security from the CDHwMT assumption. All our constructions can be conjectured to be post-quantum secure.

At the heart of our results lie several new techniques, which we believe will help in building even more advanced cryptography in isogeny-land.

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COSIC @cosic.bsky.social · 22/07/2026

We’re excited to announce the 7th edition of the Leuven Isogeny Days (Sept 16–18, 2026)! Registration is now open, join us! More info & signup: esat.kuleuven.be/cosic/projec... #LID #Isogeny #IsogenyDays

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Krijn Reijnders @krijn.isogeni.es · 16/07/2026

Excited about isogenies? Wanna claim some rewards? Solve one of the seven Isogeny Problems, the hardest open problems in isogeny-based cryptography! Full write-up now on ePrint: ia.cr/2026/1431 Webpage: isogeni.es/problems Now with EVEN MORE REWARDS!!

isogeni.es

The Isogeny Problems

A list of foremost unsolved problems in isogeny-based cryptography, with expositions by leading experts.

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Krijn Reijnders @krijn.isogeni.es · 16/07/2026

Excited to share that I've been awarded a Veni grant from the NWO! This grant allows me the freedom to explore research of my own choosing, and to achieve faster, better, and simpler post-quantum cryptography using deep mathematical insight. More info: www.ru.nl/en/about-us/...

ru.nl

Veni grants for eight Radboud researchers | Radboud University

The Dutch Research Council (NWO) has awarded a Veni grant to eight young researchers of the Radboud University and Radboudumc.

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Damien Robert @damienrobert.bsky.social · 05/07/2026

It's been a while since I last posted about MIKE, but a lot of exciting stuff happened meanwhile. MIKE is described in more details in this 4 part thread: - CSIDH bsky.app/profile/dami... - SIDH bsky.app/profile/dami... - MIKE bsky.app/profile/dami... - Speculations: bsky.app/profile/dami...

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Jonathan Komada Eriksen @jonathan.isogeny.club · 29/06/2026

TL;DR: The main idea is that given an p.p.a.v. A and an endomorphism 𝛼 of polarized degree d > 1, the points of A that are "eventually fixed by 𝛼" share similarities to an ab. var. over a finite field (both are naturally Zhat-modules), and thus Bruin's formula for the Tate-pairing generalizes 🥳

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Andrea Basso @andreavbasso.bsky.social · 14/05/2026

Round 3 of the NIST additional signatures process announced! 🎉 And SQIsign is part of it!! ⛷️⛷️

Screenshot of email announcement saying:

Nine Candidates Advance to the Third Round of the Additional Digital Signatures for the PQC Standardization Process

After 18 months of evaluation, NIST has selected nine candidates for the third round of the Additional Digital Signatures for the Post-Quantum Cryptography (PQC) Standardization Process. The advancing digital signature algorithms are:

FAEST
HAWK
MAYO
MQOM
QR-UOV
SDitH
SNOVA
SQIsign
UOV

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Tjerand Silde @tjesi.bsky.social · 12/05/2026

We have two openings at our Department of Information Security and Communication Technology at NTNU: Associate Professor in Cryptographic Engineering: www.jobbnorge.no/en/available... Professor/Associate Professor in Mobile and Computer Networks: www.jobbnorge.no/en/available... Apply by June 12!

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Aleksei Udovenko @affine.group · 11/05/2026

The paper shows how to find affine maps agreeing with an S-box on as many as possible inputs. Look for presentation at #Eurocrypt 2026 today! The code is already available. Also check out a vide-coded interactive tool, it's fun to play with: affine.group/pages/greedy...

affine.group

Greedy Extension (DDT) Algorithm

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Jonathan Komada Eriksen @jonathan.isogeny.club · 04/04/2026

Might be a bit late on this post, but wanted to take the opportunity to praise my PhD supervisor Colin Boyd, after he became an IACR Fellow this year iacr.org/fellows/2026... ! I think few people can claim to have had a positive impact on as many people's lives as Colin!

iacr.org

Colin Boyd, 2026 IACR Fellow

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Damien Robert @damienrobert.bsky.social · 01/04/2026

By the way as you know lately I have been thinking about cubical structures in terms of derived quadratic forms, and although a bit conceptual it is *amazing* for having a better understanding of what we can do with them. For instance the monodromy leak can be explained in a paragraph:

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Jonathan Komada Eriksen @jonathan.isogeny.club · 30/03/2026

Writeup of the crypto-challenge MonoDOOM ETERNAL from #KalmarCTF - A follow up from last-years MonoDOOM challenge, this time with botched side-channel protection! jonathke.github.io/monoDOOM-ETE...

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Kalmarunionen @kalmarunionendm.bsky.social · 28/03/2026

#KalmarCTF is currently well underway - and we’re once again featuring prizes sponsored by @hex-rays.bsky.social and Zellic ! Come play along by visiting kalmarc.tf

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Maria Corte-Real Santos @maria.isogeny.club · 06/03/2026

New PRISM improvements 🥳 We extended our PRISM paper to present two new variants: one that achieves strong unforgeability, and another that allows for smaller parameters and therefore faster signatures! eprint.iacr.org/2026/443.pdf

eprint.iacr.org

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Tjerand Silde @tjesi.bsky.social · 20/02/2026

Published an opinion piece (in Norwegian) about PQC (yay) vs QKD (buu) in @digi.no today, together with @jonathan.isogeny.club, Kristian Gjøsteen (NTNU), Øyvind Ytrehus (UiB), and Morten Øygarden (UiB): www.digi.no/artikler/deb...

digi.no

Spekulativ kvanteteknologi løser ikke sikkerhetsproblemene våre

Kvantedatamaskiner kan i fremtiden knekke dagens kryptografi. Derfor må vi sikre at data som sendes i dag ikke kan leses av morgendagens angripere.

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Damien Robert @damienrobert.bsky.social · 20/02/2026

Continuation and end of the thread started here: bsky.app/profile/dami... # Part 4: Speculations Previously: - Part 1: CSIDH bsky.app/profile/dami... - Part 2: SIDH bsky.app/profile/dami... - Part 3: MIKE bsky.app/profile/dami...

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Damien Robert @damienrobert.bsky.social · 20/02/2026

I am very happy to announce that thanks to the hard work of many people (The "MIKE Team"), we now have a working implementation in SageMath of MIKE (Module Isogeny Key Exchange).

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arXiv math.AG Algebraic Geometry @mathag-bot.bsky.social · 12/01/2026

Thomas Decru, Sabrina Kunzweiler: Abelian surfaces in Hesse form and explicit isogeny formulas arxiv.org/abs/2601.05922 arxiv.org/pdf/2601.05922 arxiv.org/html/2601.05922

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Tanja Lange @hyperelliptic.bsky.social · 14/01/2026

Bit of a last-minute announcement: school on isogenies 9 - 13 Feb at Okinawa Institute of Science and Technology (OIST) groups.oist.jp/tsvp/event/s... Registration deadline is tomorrow (15 Jan).

groups.oist.jp

School: Introduction to Isogeny-based Cryptography (TSVP-TP25IC)

Title: "Introduction to Isogeny-based Cryptography" Abstract: Isogeny-based cryptography is a fast-moving field, and recent developments have introduced several new techniques, making the barrier of e...

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Krijn Reijnders @krijn.isogeni.es · 03/01/2026

New year, new pairing

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ePrint Updates @eprint.ing.bot · 03/10/2025

Olingo: Threshold Lattice Signatures with DKG and Identifiable Abort (Kamil Doruk Gur, Patrick Hough, Jonathan Katz, Caroline Sandsbråten, Tjerand Silde) ia.cr/2025/1789

Abstract. We present Olingo, a framework for threshold lattice signatures that is the first to offer all desired properties for real-world implementations of quantum-secure threshold signatures: small keys and signatures, low communication and round complexity, non-interactive online signing, distributed key generation (DKG), and identifiable abort.

Our starting point is the framework of Gur, Katz, and Silde (PQCrypto 2024). We change the underlying signature scheme to Raccoon (Katsumata et al., Crypto 2024), remove the trapdoor commitments, and apply numerous improvements and optimizations to achieve all the above properties. We provide detailed proofs of security for our new framework and present concrete parameters and benchmarks.

At the 128-bit security level, for up to 1024 parties and supporting 2⁶⁰ signatures, our scheme has 2.6 KB public keys and 9.7 KB signatures; while signing requires communication of 953 KB per party. Using the LaBRADOR proof system (Beullens and Seiler, Crypto 2023), this can be further reduced to 596 KB. An optimistic non-interactive version of our scheme requires only 83 KB communication per party.

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Maria Corte-Real Santos @maria.isogeny.club · 25/09/2025

For those who missed it, the recording is live! www.youtube.com/watch?v=lvhh...

youtube.com

The Isogeny Club #7.1 Large smooth twins from short lattice vectors

YouTube video by The Isogeny Club

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Damien Robert @damienrobert.bsky.social · 15/09/2025

And you solve the failure rate problem, which was a big source of trouble in the previous implementation. And the new algorithm is simpler to implement! So very exciting result! (Although I had been spoiled already by @jonathan.isogeny.club talk at Bordeaux in May :))

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Krijn Reijnders @krijn.isogeni.es · 15/09/2025

Announcing The Isogeny Problems! A curated list of the seven foremost unsolved problems in isogeny-based cryptography. Solving one of these profound questions would mark a monumental advance, and as a resolver you'd get eternal honor and epic rewards! Full list: isogeni.es/problems

isogeni.es

The Isogeny Problems

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Jonathan Komada Eriksen @jonathan.isogeny.club · 12/09/2025

... The paper might have been out for less than 24 hours, but that is clearly plenty for yx7 to implement a more computer-algebra friendly implementation that works for any "nice" order! 🥳🥳 github.com/yyyyx4/qlapo...

github.com

GitHub - yyyyx4/qlapoti-sage: Qlapoti algorithm, generalized — a simple Sage implementation.

Qlapoti algorithm, generalized — a simple Sage implementation. - yyyyx4/qlapoti-sage

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Maria Corte-Real Santos @maria.isogeny.club · 12/09/2025

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.

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ePrint Updates @eprint.ing.bot · 11/09/2025

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.

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Tjerand Silde @tjesi.bsky.social · 09/09/2025

The EU Parliament has published a new proposal for Chat Control to mass-surveil all digital communication in Europe. The proposal is ineffective, weakens secure communication, and violates basic human privacy. This must be stopped immediately. #ChatControl csa-scientist-open-letter.org/Sep2025

csa-scientist-open-letter.org

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Krijn Reijnders @krijn.isogeni.es · 03/09/2025

Perhaps @jonathan.isogeny.club really really hates embedded devices?

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Kenny Paterson @kennyog.bsky.social · 08/07/2025

Some impressions of Longyearbyen from the last few days.

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Krijn Reijnders @krijn.isogeni.es · 07/07/2025

9 out of 10 dentists recommend solving log(p) KLPT (from @jonathan.isogeny.club's talk at ARCTICCRYPT 2025!)

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ePrint Updates @eprint.ing.bot · 20/06/2025

Evaluation of Modular Polynomials from Supersingular Elliptic Curves (Maria Corte-Real Santos, Jonathan Komada Eriksen, Antonin Leroux, Michael Meyer, Lorenz Panny) ia.cr/2025/1154

Abstract. We present several new algorithms to evaluate modular polynomials of level ℓ modulo a prime p on an input j. More precisely, we introduce two new generic algorithms, sharing the following similarities: they are based on a CRT approach; they make use of supersingular curves and the Deuring correspondence; and, their memory requirements are optimal.

The first algorithm combines the ideas behind a hybrid algorithm of Sutherland in 2013 with a recent algorithm to compute modular polynomials using supersingular curves introduced in 2023 by Leroux. The complexity (holding around several plausible heuristic assumptions) of the resulting algorithm matches the O(ℓ³log³ℓ+ℓlogp) time complexity of the best known algorithm by Sutherland, but has an optimal memory requirement.

Our second algorithm is based on a sub-algorithm that can evaluate modular polynomials efficiently on supersingular j-invariants defined over 𝔽_(p), and achieves heuristic complexity quadratic in both ℓ and log j, and linear in log p. In particular, it is the first generic algorithm with optimal memory requirement to obtain a quadratic complexity in~ℓ.

Additionally, we show how to adapt our method to the computation of other types of modular polynomials such as the one stemming from Weber’s function.

Finally, we provide an optimised implementation of the two algorithms detailed in this paper, though we emphasise that various modules in our codebase may find applications outside their use in this paper.

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COSIC @cosic.bsky.social · 16/06/2025

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

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Andrea Basso @andreavbasso.bsky.social · 10/06/2025

We (finally) published all the material from this course on SQIsign, including lecture slides and exercise sheets for the Sage laboratory. Available here: github.com/andreavico/S...

github.com

GitHub - andreavico/SQIsign_summer_school: Slides and worksheets for the introductory course on SQIsign held in Trento in May 2025

Slides and worksheets for the introductory course on SQIsign held in Trento in May 2025 - andreavico/SQIsign_summer_school

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International Security Conference 2025 @isc2025.bsky.social · 12/05/2025

We are hosting the Information Security Conference (ISC) 2025 at Sungkyunkwan University! ISC is a long-standing security conference with a 28-year history Prof. Hyungjoon Kevin Koo and Hojoon Lee will jointly serve as General Chairs this year. CFP: isc25.skku.edu/call-for-pap...

isc25.skku.edu

ISC 2025: Information Security Conference

The 28th edition of ISC will be organized by Sungkyunkwan University. The conference will be held in-person at the 600 Years Anniversary Hall, Sungkyunkwan University (Humanities & Social Sciences Campus). The proceedings of ISC 2025 will be published as a separate LNCS volume by Springer.

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Krijn Reijnders @krijn.isogeni.es · 13/05/2025

tl;dr: dr. ✅ Very happy to share that I successfully defended my thesis "Isogenies & Isometries" yesterday! A thrilling experience, would recommend, 10/10

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COSIC @cosic.bsky.social · 12/05/2025

🥇The paper "PRISM: Simple And Compact Identification and Signatures From Large Prime Degree Isogenies", co-authored by COSIC, has won the best paper award at @IACR_News #PKC 2025 in Røros, Norway. #pkc2025 Link: link.springer.com/chapter/10.1...

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Jonathan Komada Eriksen @jonathan.isogeny.club · 24/04/2025

As a surprise for everyone attending, we will even have a mystery guest joining us as well, who you don't want to miss! In fact, we have already started the train journey from Leuven! Curious about the mystery guest? Well, what are you waiting for, sign up and find out next weekend!

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Maria Corte-Real Santos @maria.isogeny.club · 23/04/2025

Good news is that we're still accepting brainstorm topics!! If you have a brainstorm idea, send us a short description by email !

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Krijn Reijnders @krijn.isogeni.es · 15/04/2025

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.

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Tjerand Silde @tjesi.bsky.social · 25/03/2025

IACR Public Key Cryptography 2025 registration is open! Please check out pkc.iacr.org/2025/registr... to attend the conference in Røros, Norway from May 12 to 15 🤩 @bordekock.bsky.social , @tiborj.bsky.social

pkc.iacr.org

PKC 2025 registration

The International Conference on Practice and Theory in Public Key Cryptography

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Luca De Feo @bsky.defeo.lu · 13/03/2025

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!

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Jonathan Komada Eriksen @jonathan.isogeny.club · 09/03/2025

GG everyone who played #KalmarCTF 2025! Writeups for my two challs: MonoDOOM: jonathke.github.io/monoDOOM A chal based on a sick sidechannel attack by @damienrobert.bsky.social ! Not-so-complex multiplication: jonathke.github.io/not-so-complex An easy chal based on complex multiplication.

jonathke.github.io

Jonathan Komada Eriksen - Notes

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