Cycles in the Supersingular ℓ-Isogeny Graph and Corresponding Endomorphisms

Efrat Bank, Catalina Camacho-Navarro, Kirsten Eisenträger, Travis Morrison, Jennifer Park

Research output: Chapter in Book/Report/Conference proceedingChapter


We study the problem of generating the endomorphism ring of a supersingular elliptic curve by two cycles in ℓ-isogeny graphs. We prove a necessary and sufficient condition for the two endomorphisms corresponding to two cycles to be linearly independent, expanding on the work by Kohel in his thesis. We also give a criterion under which the ring generated by two cycles is not a maximal order. We give some examples in which we compute cycles which generate the full endomorphism ring. The most difficult part of these computations is the calculation of the trace of these cycles. We show that a generalization of Schoof’s algorithm can accomplish this computation efficiently.

Original languageEnglish (US)
Title of host publicationAssociation for Women in Mathematics Series
Number of pages26
StatePublished - 2019

Publication series

NameAssociation for Women in Mathematics Series
ISSN (Print)2364-5733
ISSN (Electronic)2364-5741

All Science Journal Classification (ASJC) codes

  • General Mathematics
  • Gender Studies


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