Paper 2019/266

Fast constant-time gcd computation and modular inversion

Daniel J. Bernstein and Bo-Yin Yang

Abstract

This paper introduces streamlined constant-time variants of Euclid's algorithm, both for polynomial inputs and for integer inputs. As concrete applications, this paper saves time in (1) modular inversion for Curve25519, which was previously believed to be handled much more efficiently by Fermat's method, and (2) key generation for the ntruhrss701 and sntrup4591761 lattice-based cryptosystems.

Metadata
Available format(s)
PDF
Category
Implementation
Publication info
A minor revision of an IACR publication in Tches 2019
Keywords
Euclid's algorithmgreatest common divisorgcdmodular reciprocalmodular inversionconstant-time computationsbranchless algorithmsalgorithm designNTRUCurve25519
Contact author(s)
authorcontact-safegcd @ box cr yp to
History
2019-04-13: revised
2019-03-06: received
See all versions
Short URL
https://ia.cr/2019/266
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2019/266,
      author = {Daniel J.  Bernstein and Bo-Yin Yang},
      title = {Fast constant-time gcd computation and modular inversion},
      howpublished = {Cryptology ePrint Archive, Paper 2019/266},
      year = {2019},
      note = {\url{https://eprint.iacr.org/2019/266}},
      url = {https://eprint.iacr.org/2019/266}
}
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