Post-quantum commutative group actions from oriented superspecial abelian varieties
Abstract
We study the cryptographic use of Shimura class group actions on superspecial principally polarized abelian varieties equipped with a CM orientation, within the context of post-quantum cryptography. Besides giving an accessible introduction to the topic, illustrated with many examples, we provide tools for representing CM orientations through higher-dimensional isogenies and for computing the Shimura class group action in the restricted effective group action model. Here, key auxiliary results are a version of Kani's lemma "with CM" and a trick that often allows to halve the ambient dimension. We also give a method for finding superspecial principally polarized abelian surfaces that are oriented by a given CM order, which is extracted from an algebraic framework for studying CM orientations using the Ibukiyama-Katsura-Oort correspondence. We also analyze obstructions to transitivity of the Shimura class group action, related to the characteristic-zero notion of CM type.
Related
- Ekedahl-Oort strata with a superspecial factor in unitary Shimura varieties
- Finite Borel asymptotic dimension of bounded-to-one commutative monoid actions
- Asymptotic dimension of commutative monoid actions
- Non-commutative Fano varieties and three-dimensional minifolds
- The regionally proximal relation for commutative semigroup actions
BibTeX
@misc{castryck2026postquantum,
title = {{Post-quantum commutative group actions from oriented superspecial abelian varieties}},
author = {Wouter Castryck and Bogdan Adrian Dina and Péter Kutas and Gioella Lorenzon},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.27922},
eprint = {2610.27922},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.27922},
note = {CC BY-SA 4.0},
}
RIS
TY - UNPB
TI - Post-quantum commutative group actions from oriented superspecial abelian varieties
AU - Wouter Castryck
AU - Bogdan Adrian Dina
AU - Péter Kutas
AU - Gioella Lorenzon
PY - 2026
DA - 2026/10/20
PB - arXiv
DO - 10.48550/arxiv.2610.27922
UR - https://arxiv.org/abs/2610.27922
AB - We study the cryptographic use of Shimura class group actions on superspecial principally polarized abelian varieties equipped with a CM orientation, within the context of post-quantum cryptography. Besides giving an accessible introduction to the topic, illustrated with many examples, we provide tools for representing CM orientations through higher-dimensional isogenies and for computing the Shimura class group action in the restricted effective group action model. Here, key auxiliary results are a version of Kani's lemma "with CM" and a trick that often allows to halve the ambient dimension. We also give a method for finding superspecial principally polarized abelian surfaces that are oriented by a given CM order, which is extracted from an algebraic framework for studying CM orientations using the Ibukiyama-Katsura-Oort correspondence. We also analyze obstructions to transitivity of the Shimura class group action, related to the characteristic-zero notion of CM type.
ER -