The canonical representation of an elliptic curve group element.
This should represent the affine coordinates of the point corresponding
to this group element.
Constants and convenience functions that collectively define the Montgomery model
of the curve. In this model, the curve equation is
b * y² = x³ + a * x² + x, for constants a and b.
Constants and convenience functions that collectively define the Twisted Edwards model
of the curve. In this model, the curve equation is
a * x² + y² = 1 + d * x² * y², for constants a and d.