private static int CheckPoint(uint[] x, uint[] y) { uint[] t = X448Field.Create(); uint[] u = X448Field.Create(); uint[] v = X448Field.Create(); X448Field.Sqr(x, u); X448Field.Sqr(y, v); X448Field.Mul(u, v, t); X448Field.Add(u, v, u); X448Field.Mul(t, -C_d, t); X448Field.SubOne(t); X448Field.Add(t, u, t); X448Field.Normalize(t); return(X448Field.IsZero(t)); }