CTIDH: faster constant-time CSIDH

CTIDH: faster constant-time CSIDH

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...

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Bibliographic Details
Main Authors: Gustavo Banegas, Daniel J. Bernstein, Fabio Campos, Tung Chou, Tanja Lange, Michael Meyer, Benjamin Smith, Jana Sotáková
Format: Article
Language:English
Published: Ruhr-Universität Bochum 2021-08-01
Series:Transactions on Cryptographic Hardware and Embedded Systems
Subjects:
post-quantum cryptography
non-interactive key exchange
small keys
isogeny-based cryptography
CSIDH
constant-time algorithms
Online Access:https://tches.iacr.org/index.php/TCHES/article/view/9069
Description
Summary: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.
ISSN:2569-2925

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