Open AccessCTIDH: faster constant-time CSIDH
Author(s) -
Gustavo Banegas,
Daniel J. Bernstein,
Fábio Campos,
TaiLi Chou,
Tanja Lange,
Michaël Meyer,
Benjamin Smith,
Jana Sotáková
Publication year - 2021
Publication title -
iacr transactions on cryptographic hardware and embedded systems
Language(s) - English
Resource type - Journals
ISSN - 2569-2925
DOI - 10.46586/tches.v2021.i4.351-387
Subject(s) - key (lock) , constant (computer programming) , computer science , algorithm , key space , space (punctuation) , mathematics , theoretical computer science , cryptography , computer security , programming language , operating system
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.