Paper 2019/1244

A Note on a Static SIDH Protocol

Samuel Dobson, Trey Li, and Lukas Zobernig

Abstract

It is well known, due to the adaptive attack by Galbraith, Petit, Shani, and Ti (GPST), that plain SIDH is insecure in the static setting. Recently, Kayacan's preprint "A Note on the Static-Static Key Agreement Protocol from Supersingular Isogenies", ePrint 2019/815, presented two possible fixes. Protocol A (also known as 2-SIDH, a low-degree instantiation of the more general k-SIDH) has been broken by Dobson, Galbraith, LeGrow, Ti, and Zobernig. In this short note we will show how to break Protocol B in one oracle query per private key bit and $O(1)$ local complexity.

Metadata
Available format(s)
PDF
Category
Public-key cryptography
Publication info
Preprint. Minor revision.
Keywords
cryptanalysissupersingular isogeny Diffie-Hellman
Contact author(s)
samuel dobson nz @ gmail com
trey li @ auckland ac nz
lukas zobernig @ auckland ac nz
History
2019-10-24: received
Short URL
https://ia.cr/2019/1244
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2019/1244,
      author = {Samuel Dobson and Trey Li and Lukas Zobernig},
      title = {A Note on a Static SIDH Protocol},
      howpublished = {Cryptology ePrint Archive, Paper 2019/1244},
      year = {2019},
      note = {\url{https://eprint.iacr.org/2019/1244}},
      url = {https://eprint.iacr.org/2019/1244}
}
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