Paper 2022/880

Efficient supersingularity testing over $\mathbb{F}_p$ and CSIDH key validation

Gustavo Banegas, Inria and Laboratoire d’Informatique de l’Ecole polytechnique, Institut Polytechnique de Paris, Palaiseau, France
Valerie Gilchrist, University of Waterloo, Canada, Inria and Laboratoire d’Informatique de l’Ecole polytechnique, Institut Polytechnique de Paris, Palaiseau, France
Benjamin Smith, Inria and Laboratoire d’Informatique de l’Ecole polytechnique, Institut Polytechnique de Paris, Palaiseau, France
Abstract

Many public-key cryptographic protocols, notably non-interactive key exchange (NIKE), require incoming public keys to be validated to mitigate some adaptive attacks. In CSIDH, an isogeny-based post-quantum NIKE, a key is deemed legitimate if the given Montgomery coefficient specifies a supersingular elliptic curve over the prime field. In this work, we survey the current supersingularity tests used for CSIDH key validation, and implement and measure two new alternative algorithms. Our implementation shows that we can determine supersingularity substantially faster, and using less memory, than the state-of-the-art.

Metadata
Available format(s)
PDF
Category
Public-key cryptography
Publication info
Published elsewhere. Mathcrypt 2022
Keywords
Isogenies Key validation Supersingularity Elliptic Curves
Contact author(s)
gustavo @ cryptme in
vgilchrist @ uwaterloo ca
smith @ lix polytechnique fr
History
2022-07-26: revised
2022-07-05: received
See all versions
Short URL
https://ia.cr/2022/880
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2022/880,
      author = {Gustavo Banegas and Valerie Gilchrist and Benjamin Smith},
      title = {Efficient supersingularity testing over $\mathbb{F}_p$ and {CSIDH} key validation},
      howpublished = {Cryptology {ePrint} Archive, Paper 2022/880},
      year = {2022},
      url = {https://eprint.iacr.org/2022/880}
}
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