Post-doc in post-quantum cryptography. Mostly isogenies nowadays. See krijnreijnders.comhttps://bsky.app/profile/krijn.isogeni.eshttps://bsky.app/profile/krijn.isogeni.es/post/3msg6aaijwc2yUpdate to isogeni.es Now includes isogeny papers from arXiv! You'll never have to visit either ePrint or arXiv anymore 😊 https://isogeni.es06 Aug 2026 13:41 +0000at://did:plc:7leog3vsgnpkw3numvhunezd/app.bsky.feed.post/3msg6aaijwc2yhttps://bsky.app/profile/krijn.isogeni.es/post/3mqrtjbeql22mExcited 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!! https://isogeni.es/problems16 Jul 2026 18:11 +0000at://did:plc:7leog3vsgnpkw3numvhunezd/app.bsky.feed.post/3mqrtjbeql22mhttps://bsky.app/profile/krijn.isogeni.es/post/3mqqxzjakds2sExcited 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: https://www.ru.nl/en/about-us/news/veni-grants-for-eight-radboud-researchers16 Jul 2026 09:59 +0000at://did:plc:7leog3vsgnpkw3numvhunezd/app.bsky.feed.post/3mqqxzjakds2shttps://bsky.app/profile/krijn.isogeni.es/post/3mk2sbpupnc2qEven though its not actually post-quantum crypto, I would never pass on a cool application of the Tate pairing: Much faster subgroup membership testing! (the credits go to the rest of the team, though, who write amazingly fast code!!) [contains quote post or other embedded content]22 Apr 2026 05:46 +0000at://did:plc:7leog3vsgnpkw3numvhunezd/app.bsky.feed.post/3mk2sbpupnc2qhttps://bsky.app/profile/krijn.isogeni.es/post/3mijwqrww2k22I should add to this: winner of best paper award at Eurocrypt 2026!! As a single author. During his PhD. Incredible achievement!(protip: he will graduate soon-ish 👀) [contains quote post or other embedded content]02 Apr 2026 19:26 +0000at://did:plc:7leog3vsgnpkw3numvhunezd/app.bsky.feed.post/3mijwqrww2k22https://bsky.app/profile/krijn.isogeni.es/post/3mgwpk22bgk2pThomas and I looked at directed isogeny graphs! In dim 1, we often ignore directedness, as there are only 2 "problematic" curves. Not so in dim 2: we analyze the action of automorphisms on level structures and the resulting directed graphs. Crucial: Directed (2,2)-graphs looks Ramanujan after all! [contains quote post or other embedded content]13 Mar 2026 10:31 +0000at://did:plc:7leog3vsgnpkw3numvhunezd/app.bsky.feed.post/3mgwpk22bgk2phttps://bsky.app/profile/krijn.isogeni.es/post/3mbjflwznoc2cNew year, new pairing [contains quote post or other embedded content]03 Jan 2026 12:23 +0000at://did:plc:7leog3vsgnpkw3numvhunezd/app.bsky.feed.post/3mbjflwznoc2chttps://bsky.app/profile/krijn.isogeni.es/post/3madeidxjec2iDear publishers, this may come as a shock to you, but in general, I do not want to download a tiny .bib file for every reference. I simply want to copy-paste.19 Dec 2025 09:22 +0000at://did:plc:7leog3vsgnpkw3numvhunezd/app.bsky.feed.post/3madeidxjec2i