The author incorrectly calling them "elliptical curves" is like nails on a chalkboard. An "elliptical" is an exercise machine or an adjective used to describe something shaped like an ellipse. The set of points in a field satisfying an equation of the form y^2 = x^3 + ax + b (which set, when enlarged to include the point at infinity and associated with the point addition group law, forms an abelian group) is an "elliptic curve".
Paxos is an enterprise private blockchain snake oil company, but nobody there even knows it. When asked how they solve problems X, Y and Z, it turns out they have a blog article about how they haven't invented the solution yet. Tall order. Maybe commissions on their itBit exchange will keep them solvent enough to keep trying.
This is an excellent and rare ECC primer in that it's aimed at software developers not mathematicians. I know what python looks like, whereas I don't know every mathematical symbol. Bookmarking.