Krijn Reijnders
This is my website, which serves to host some of my (professional) writings, some thoughts that I have at times and an online version of my cv.
If you are interested in my work, I will be a speaker at a few upcoming events:
- MaGIC 2026: a workshop on cryptographic group actions at Borgo Lanciano, Italy, from May 5th to May 8th. (link)
- Course: an introduction to post-quantum cryptography, at Radboud University, Nijmegen, in the Netherlands, from June 22th to June 26th. (link)
- AM-PQC 2026: a workshop on algebraic methods in post-quantum cryptography, in Ohrid, Macedonia, from August 10th to August 14th. (link)
post-quantum cryptography
My research focuses on post-quantum cryptography, specifically code-based and isogeny-based schemes. Essentially, I look at isogenies and isometries.
Within isogenies, my more specific research interests are (applications of) pairings and Kummer surfaces. Within isometries, I focus on the interplay between automorphism groups and matrix code equivalence.
the isogeny club
For the first two years, I organized The Isogeny Club, together with Jonathan Komada Eriksen (www). Since, May 2024, I have stepped back and taken a more advisory role, with Maria Corte-Real Santos (www) taking over as co-host of the bi-weekly virtual seminar for young isogenists. The Isogeny Club also hosts the Brainstorm Days as an affiliated event (for all isogenists) at Eurocrypt, where we brainstorm on cutting-edge ideas in isogeny-based cryptography.
the isogeny problems
In July 20205, I reached out to a small group of leading experts and asked them what the most fundamental unsolved problems in isogeny-based cryptography were. This resulted in a curated list of 7 key problems. The resolution of any of these questions would mark a monumental advance in our field. For solving a problem on the list, you receive an epic reward, and you can also contribute your own rewards if you want. The list is available at