CSIDH Ring Walk 2D: Isogeny Key Exchange Cross-Section

This is the 2D cross-section companion to the 3D CSIDH isogeny key-exchange simulator. Rather than embedding six per-prime cyclic walks into one 3D basis point, this version draws each of the six small-prime rings flat and independent, so you can watch every coordinate of the class-group vector move on its own circle. Alice and Bob each pick a secret vector of small integers, walk from the shared base curve E0 out to their own public curve one ring-step at a time, exchange those public curves, and then each applies their own secret walk to the curve they received. Because each ring's position is just modular addition — and modular addition commutes — both walks land on the exact same six ring positions: the live vectors, step counter, and the converging gold markers confirm the match in real time. Drag to pan and scroll to zoom into any ring.