A note on key control in CSIDH

Antonio Sanso

Paper 2022/847

A note on key control in CSIDH

Antonio Sanso, Ethereum Foundation, Ruhr Universität Bochum

Abstract

In this short note we explore a particular behaviour of the CSIDH key exchange that leads to a very special form of (shared) key control via the use of the quadratic twists. This peculiarity contained in CSIDH with regard to quadratic twists was already noted in the original CSDIH work and used in several subsequent papers but we believe spelling out this in the form of an attack might be useful to the wider community.

Metadata

Available format(s): PDF
Category: Public-key cryptography
Publication info: Preprint.
Keywords: CSIDH key exchange isogeny
Contact author(s): antonio sanso @ gmail com
History: 2022-08-01: last of 2 revisions; 2022-06-27: received; See all versions
Short URL: https://ia.cr/2022/847
License: CC BY

BibTeX

@misc{cryptoeprint:2022/847,
      author = {Antonio Sanso},
      title = {A note on key control in {CSIDH}},
      howpublished = {Cryptology {ePrint} Archive, Paper 2022/847},
      year = {2022},
      url = {https://eprint.iacr.org/2022/847}
}