Paper 2025/102
A practical distinguisher on the full Skyscraper permutation
Abstract
Skyscraper is a cryptographic permutation published in TCHES 2025, optimized for use in proof systems such as PlonK. This primitive is based on a 10-round Feistel network combining $x^2$ monomials and lookup-based functions to achieve competitive plain performances and efficiency in proof systems supporting lookups. In terms of security, the $x^2$ monomials are supposed to provide security against statistical attacks, while lookups are supposed to provide security against algebraic attacks. In this note, we show that this primitive has a much lower security margin than expected. Using a rebound attack, we find practical truncated differentials on the full permutation. As a corollary, we also find a practical collision attack on the compression function based on a 9-round Skyscraper permutation, which significantly reduces the security margin of the primitive. All of these attacks have been implemented and work in practice.
Metadata
- Available format(s)
-
PDF
- Category
- Secret-key cryptography
- Publication info
- Preprint.
- Keywords
- Skyscrapersplit-and-lookuprebound attackcryptanalysis
- Contact author(s)
- antoine bak @ inria fr
- History
- 2025-01-23: approved
- 2025-01-22: received
- See all versions
- Short URL
- https://ia.cr/2025/102
- License
-
CC BY
BibTeX
@misc{cryptoeprint:2025/102,
author = {Antoine Bak},
title = {A practical distinguisher on the full Skyscraper permutation},
howpublished = {Cryptology {ePrint} Archive, Paper 2025/102},
year = {2025},
url = {https://eprint.iacr.org/2025/102}
}
