Computing of Odd Degree Isogenies on Supersingular Twisted Edwards Curves

An overview of the properties of three classes of curves in generalized Edwards form Ea,d with two parameters is given. The known formulas for the odd degree isogenies on curves Ed with one parameter are generalized to all classes of curves in Edwards form, and Theorem 1 on the isogenic mapping of the points of these curves is proved. The analysis of the known effective method for computing isogenies in Farashahi-Hosseini w-coordinates, justified for the curve Ed, is given. Theorem 2 proves the applicability of this method to the class of twisted Edwards curves. Examples of 3- and 5-isogenies of twisted Edwards curves are given. Methods for bypassing the exceptional points of such curves in PQC cryptosystems like CSIDH are proposed.