QUT ePrints

Linearity within the SMS4 Block Cipher

Z'aba, Muhammad Reza, Simpson, Leonie, Dawson, Edward, & Wong, Kenneth Koon-Ho (2010) Linearity within the SMS4 Block Cipher. In Lecture Notes in Computer Science : Information Security and Cryptology (ICISC 2009), Springer-Verlag, Beijing, China, pp. 248-265.

View at publisher

Abstract

We present several new observations on the SMS4 block cipher, and discuss their cryptographic significance. The crucial observation is the existence of fixed points and also of simple linear relationships between the bits of the input and output words for each component of the round functions for some input words. This implies that the non-linear function T of SMS4 does not appear random and that the linear transformation provides poor diffusion. Furthermore, the branch number of the linear transformation in the key scheduling algorithm is shown to be less than optimal. The main security implication of these observations is that the round function is not always non-linear. Due to this linearity, it is possible to reduce the number of effective rounds of SMS4 by four. We also investigate the susceptibility of SMS4 to further cryptanalysis. Finally, we demonstrate a successful differential attack on a slightly modified variant of SMS4. These findings raise serious questions on the security provided by SMS4.

Impact and interest:

0 citations in Scopus
Search Google Scholar™
0 citations in Web of Science®

Citation countsare sourced monthly from Scopus and Web of Science® citation databases.

These databases contain citations from different subsets of available publications and different time periods and thus the citation count from each is usually different. Some works are not in either database and no count is displayed. Scopus includes citations from articles published in 1996 onwards, and Web of Science® generally from 1980 onwards.

Citations counts from the Google Scholar™ indexing service can be viewed at the linked Google Scholar™ search.

Full-text downloads:

167 since deposited on 13 Dec 2010
70 in the past twelve months

Full-text downloadsdisplays the total number of times this work’s files (e.g., a PDF) have been downloaded from QUT ePrints as well as the number of downloads in the previous 365 days. The count includes downloads for all files if a work has more than one.

ID Code: 39134
Item Type: Conference Paper
Keywords: SMS4, block cipher, round function, fixed point, encryption, key scheduling algorithm, linearity, cryptanalysis
DOI: 10.1007/978-3-642-16342-5_18
ISBN: 978-3-642-16341-8
ISSN: 0302-9743
Subjects: Australian and New Zealand Standard Research Classification > INFORMATION AND COMPUTING SCIENCES (080000) > DATA FORMAT (080400) > Data Encryption (080402)
Divisions: Past > QUT Faculties & Divisions > Faculty of Science and Technology
Past > Institutes > Information Security Institute
Copyright Owner: Copyright 2010 Springer-Verlag.
Deposited On: 13 Dec 2010 12:53
Last Modified: 18 Jul 2014 15:00

Export: EndNote | Dublin Core | BibTeX

Repository Staff Only: item control page