A Note on (2, 2)-isogenies via Theta Coordinates

ePrint Report: A Note on (2, 2)-isogenies via Theta Coordinates

Jianming Lin, Saiyu Wang, Chang-An Zhao

In this paper, we revisit the algorithm for computing chains of $(2, 2)$-isogenies between products of elliptic curves via theta coordinates proposed by Dartois et al. For each fundamental block of this algorithm, we provide a explicit inversion-free version. Besides, we exploit a novel technique of $x$-only ladder to speed up the computation of gluing isogeny. Finally, we present a mixed optimal strategy, which …

algorithm block computing elliptic eprint report products report theta wang