SIDH with masked torsion point images

Tako Boris Fouotsa

Paper 2022/1054

SIDH with masked torsion point images

Tako Boris Fouotsa

, École Polytechnique Fédérale de Lausanne

Abstract

We propose a countermeasure to the Castryck-Decru attack on SIDH. The attack heavily relies on the images of torsion points. The main input to our countermeasure consists in masking the torsion point images in SIDH in a way they are not exploitable in the attack, but can be used to complete the key exchange. This comes with a change in the form the field characteristic and a considerable increase in the parameter sizes.

Note: This note has been extended and merged with ePrint 2022/1019 in ePrint 2023/013. After a rigorous security analysis, the sizes of the parameters were increased. Please check ePrint 2023/013 for the updates.

Metadata

Available format(s): PDF
Category: Public-key cryptography
Publication info: Preprint.
Keywords: Post-quantum cryptography supersingular isogenies SIDH SIKE torsion point attacks
Contact author(s): tako fouotsa @ epfl ch
History: 2023-02-07: revised; 2022-08-15: received; See all versions
Short URL: https://ia.cr/2022/1054
License: CC BY

BibTeX

@misc{cryptoeprint:2022/1054,
      author = {Tako Boris Fouotsa},
      title = {{SIDH} with masked torsion point images},
      howpublished = {Cryptology {ePrint} Archive, Paper 2022/1054},
      year = {2022},
      url = {https://eprint.iacr.org/2022/1054}
}