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

DOI:

https://doi.org/10.46586/tches.v2021.i4.351-387

Keywords:

post-quantum cryptography, non-interactive key exchange, small keys, isogeny-based cryptography, CSIDH, constant-time algorithms

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.

Published

2021-08-11

How to Cite

Banegas, G., Bernstein, D. J., Campos, F., Chou, T., Lange, T., Meyer, M., Smith, B., & Sotáková, J. (2021). CTIDH: faster constant-time CSIDH. IACR Transactions on Cryptographic Hardware and Embedded Systems, 2021(4), 351–387. https://doi.org/10.46586/tches.v2021.i4.351-387

Issue

Section

Articles