International Association for Cryptologic Research

International Association
for Cryptologic Research

CryptoDB

Paper: CTIDH: faster constant-time CSIDH

Authors:
Gustavo Banegas , Inria and Laboratoire d’Informatique de l’Ecole polytechnique, Institut Polytechnique de Paris, Palaiseau, France
Daniel J. Bernstein , Department of Computer Science, University of Illinois at Chicago, USA; Horst Görtz Institute for IT Security, Ruhr University Bochum, Germany
Fabio Campos , Max Planck Institute for Security and Privacy, Bochum, Germany
Tung Chou , Academia Sinica, Taipei, Taiwan
Tanja Lange , Eindhoven University of Technology, Eindhoven, The Netherlands
Michael Meyer , Technical University of Darmstadt, Darmstadt, Germany
Benjamin Smith , Inria and Laboratoire d’Informatique de l’Ecole polytechnique, Institut Polytechnique de Paris, Palaiseau, France
Jana Sotáková , Institute for Logic, Language and Computation, University of Amsterdam, The Netherlands; QuSoft
Download:
DOI: 10.46586/tches.v2021.i4.351-387
URL: https://tches.iacr.org/index.php/TCHES/article/view/9069
Search ePrint
Search Google
Abstract: This paper introduces a new key space for CSIDH and a new algorithm for constant-time evaluation of the CSIDH group action. The key space is not useful with previous algorithms, and the algorithm is not useful with previous key spaces, but combining the new key space with the new algorithm produces speed records for constant-time CSIDH. For example, for CSIDH-512 with a 256-bit key space, the best previous constant-time results used 789000 multiplications and more than 200 million Skylake cycles; this paper uses 438006 multiplications and 125.53 million cycles.
Video from TCHES 2021
BibTeX
@article{tches-2021-31320,
  title={CTIDH: faster constant-time CSIDH},
  journal={IACR Transactions on Cryptographic Hardware and Embedded Systems},
  publisher={Ruhr-Universität Bochum},
  volume={2021, Issue 4},
  pages={351-387},
  url={https://tches.iacr.org/index.php/TCHES/article/view/9069},
  doi={10.46586/tches.v2021.i4.351-387},
  author={Gustavo Banegas and Daniel J. Bernstein and Fabio Campos and Tung Chou and Tanja Lange and Michael Meyer and Benjamin Smith and Jana Sotáková},
  year=2021
}