Paper 2026/2379
Settling Conjectures on Linear Structures of Inverse ChiChi Generalizations Four Proofs and a Counterexample
, Ruhr University Bochum, Shandong UniversityAbstract
Belkheyar et al. introduced ChiChi as the even-dimensional, low-latency nonlinear core of ChiLow (Eurocrypt 2025), and Andreoli et al. generalized it into the SWAP and 4-cycle families (ToSC 2025/3), conjecturing five bounds on the linear height and component linear nullity of their inverses, supported by experiments in small dimensions. We settle all five conjectures: Conjectures 1–4 hold for every admissible branch length, and Conjecture 5 is false. In addition, we derive consequences for ChiLow's design and correct one value in the data of Andreoli et al.
Metadata
- Available format(s)
-
PDF
- Category
- Secret-key cryptography
- Publication info
- Preprint.
- Keywords
- ChiChiChiLowchi functionlinear cryptanalysislinear nullitylinear heightBoolean functions
- Contact author(s)
-
hui wang2025 @ mail sdu edu cn
ricardo rodriguezreveco @ rub de
kai hu @ sdu edu cn - History
- 2026-10-08: approved
- 2026-10-06: received
- See all versions
- Short URL
- https://ia.cr/2026/2379
- License
-
CC BY
BibTeX
@misc{cryptoeprint:2026/2379,
author = {Hui Wang and Ricardo Rodriguez Reveco and Kai Hu},
title = {Settling Conjectures on Linear Structures of Inverse {ChiChi} Generalizations Four Proofs and a Counterexample},
howpublished = {Cryptology {ePrint} Archive, Paper 2026/2379},
year = {2026},
url = {https://eprint.iacr.org/2026/2379}
}
