Cantor over finite field

[jvoight]

I feel like this should work:

_<x> := PolynomialRing(Rationals());
f := x^5 - 3*x^4 + 5*x^3 + 27*x^2 + 18*x;
X := HyperellipticCurve(f);
_ := HeuristicEndomorphismAlgebra(X : CC := true);
geoendorep := GeometricEndomorphismRepresentation(X);
M := geoendorep[2][1];
X_red := ChangeRing(X, GF(25));
P_red := Random([P : P in Points(X_red) | P[2] ne 0]);
// doesn't work
CantorFromMatrixAmbientSplit(X_red,P_red,X_red,P_red,M);