Paper 2009/360
Cryptanalysis of a Generalized Unbalanced Feistel Network Structure
Ruilin Li, Bing Sun, Chao Li, and Longjiang Qu
Abstract
This paper reevaluates the security of GF-NLFSR, a new kind of generalized unbalanced Feistel network structure that was proposed at ACISP 2009. We show that GF-NLFSR itself reveals a very slow diffusion rate, which could lead to several distinguishing attacks. For GF-NLFSR containing $n$ sub-blocks, we find an $n^2$-round integral distinguisher by algebraic methods and further use this integral to construct an $(n^2+n-2)$-round impossible differential distinguisher. Compared with the original $(3n-1)$-round integral and $(2n-1)$-round impossible differential, ours are significantly better. Another contribution of this paper is to introduce a kind of non-surjective attack by analyzing a variant structure of GF-NLFSR, whose provable security against differential and linear cryptanalysis can also be provided. The advantage of the proposed non-surjective attack is that traditional non-surjective attack is only applicable to Feistel ciphers with non-surjective (non-uniform) round functions, while ours could be applied to block ciphers with bijective ones. Moreover, its data complexity is $\mathcal{O}(l)$ with $l$ the block length.
Metadata
- Available format(s)
-
PDF
PS
- Category
- Secret-key cryptography
- Publication info
- Published elsewhere. ACISP 2010
- Keywords
- block ciphersgeneralized unbalanced Feistel networkintegral attackimpossible differential attacknon-surjective attack
- Contact author(s)
- securitylrl @ gmail com
- History
- 2012-06-20: last of 3 revisions
- 2009-07-22: received
- See all versions
- Short URL
- https://ia.cr/2009/360
- License
-
CC BY
BibTeX
@misc{cryptoeprint:2009/360,
author = {Ruilin Li and Bing Sun and Chao Li and Longjiang Qu},
title = {Cryptanalysis of a Generalized Unbalanced Feistel Network Structure},
howpublished = {Cryptology ePrint Archive, Paper 2009/360},
year = {2009},
note = {\url{https://eprint.iacr.org/2009/360}},
url = {https://eprint.iacr.org/2009/360}
}
