Paper 2007/449
Generic Attacks on Unbalanced Feistel Schemes with Expanding Functions
Jacques Patarin, Valérie Nachef, and Côme Berbain
Abstract
\begin{abstract} Unbalanced Feistel schemes with expanding functions are used to construct pseudo-random permutations from $kn$ bits to $kn$ bits by using random functions from $n$ bits to $(k-1)n$ bits. At each round, all the bits except $n$ bits are changed by using a function that depends only on these $n$ bits. C.S.Jutla \cite{Jut} investigated such schemes, which he denotes by $F^d_k$, where $d$ is the number of rounds. In this paper, we describe novel Known Plaintext Attacks (KPA) and Non Adaptive Chosen Plaintext Attacks (CPA-1) against these schemes. With these attacks we will often be able to improve the result of C.S.Jutla. We also give precise formulas for the complexity of our attacks in $d$, $k$ and $n$. \end{abstract}
Note: There are new attacks in Section 6.
Metadata
- Available format(s)
-
PDF
- Publication info
- Published elsewhere. extended version of a paper published at Asiacrypt 2007
- Keywords
- block ciphers
- Contact author(s)
- valerie nachef @ u-cergy fr
- History
- 2009-04-05: last of 2 revisions
- 2007-12-05: received
- See all versions
- Short URL
- https://ia.cr/2007/449
- License
-
CC BY
BibTeX
@misc{cryptoeprint:2007/449,
author = {Jacques Patarin and Valérie Nachef and Côme Berbain},
title = {Generic Attacks on Unbalanced Feistel Schemes with Expanding Functions},
howpublished = {Cryptology {ePrint} Archive, Paper 2007/449},
year = {2007},
url = {https://eprint.iacr.org/2007/449}
}