Isogeny Club

5 November 2025

On October 7th, Sebastian Spindler gave the online talk “Counting ℓ-isogenies with different modular polynomials” as part of the seventh season of the Isogeny Club. The talk covered both the CRYPTO paper “More Efficient Isogeny Proofs of Knowledge via Canonical Modular Polynomials”, which is a joint work of the QuSAC group and CODE colleague Sören Kleine, as well as subsequent, not yet published follow-up work that investigates other modular polynomials. A recording of the talk can be found on YouTube, and the slides are available on the website of the Isogeny Club.

Aktuelles

Crypto Day

On September 25th and 26th, Sebastian Spindler participated in the 39th Crypto Day, which was hosted by the genua GmbH in Kirchheim near Munich. At the event, Sebastian had the opportunity to converse with researchers from other universities and from the industry mainly about practical aspects of cryptography. Additionally, in his talk “Isogeny Proofs of Knowledge – A Survey” Sebastian gave an overview over the evolution of proofs of knowledge for isogeny paths over the last two years.

Isogeny Days 6

From September 10th to 12th, Marzio Mula, Shernyce Duncombe and Sebastian Spindler attended the sixth edition of the isogeny days in Leuven. Each day of the workshop was separated into two parts: In the morning current research results and ongoing projects in isogeny-based cryptography were presented by various researchers, whereas in the afternoon new research ideas were explored in smaller brainstorming groups.

Young Researcher Crypto Seminar

From September 1st to 3rd, Sebastian Spindler attended the Young Researcher Crypto Seminar in Karlsruhe, where he met with fellow early career researchers to discuss current developments in cryptology. In his talk “The supersingular (ℓ-)isogeny graph”, Sebastian furthermore presented his preprint “Exploring Kaneko’s bound: On multi-edges, loops and the diameter of the supersingular ℓ-isogeny graph”, which he published in the IACR Cryptology ePrint Archive together with Sebastiano Boscardin from the Eindhoven University of Technology.

3 Papers accepted at ASIACRYPT 2025

This year, three papers by the QUSAC group were accepted at the renowned ASIACRYPT conference. The 31st edition of the International Conference on the Theory and Application of Cryptology and Information Security – ASIACRYPT 2025 – will take place this year from December 8-12 in Melbourne, Australia. Below are brief summaries of the three accepted papers:

BIRS workshop “Isogeny Graphs in Cryptography”

From August 3rd to 8th, Sebastian Spindler attended the workshop “Isogeny Graphs in Cryptography” in Canada. In his lightning talk “On the diameter of the supersingular ℓ-isogeny graph” Sebastian presented part of his new preprint “Exploring Kaneko’s bound: On multi-edges, loops and the diameter of the supersingular ℓ-isogeny graph” that he recently published together with Sebastiano Boscardin from the Eindhoven University of Technology.

Attending ArcticCrypt 2025

From July 6th to 11th, the QuSAC group attended the 2025 edition of ArcticCrypt – the world’s northernmost cryptography conference – in Longyearbyen, Svalbard. Prof. Slamanig was invited to chair the conference's session on "Mathematical Aspects of Cryptography", and Sebastian Spindler presented the paper “More Efficient Isogeny Proofs of Knowledge via Canonical Modular Polynomials”.