A peculiar higher order differential of CLEFIA

Author

Shibayama, Naoki ; Kaneko, Tetsuya

Author_Institution

Dept. of Electr. Eng., Tokyo Univ. of Sci., Tokyo, Japan

fYear

2012

fDate

28-31 Oct. 2012

Firstpage

526

Lastpage

530

Abstract

CLEFIA is a 128-bit block cipher proposed by Shirai et al. in 2007. In this paper, we focused on a higher order differential of CLEFIA. It has been reported that CLEFIA has 6-round saturation characteristics using 32-nd order differential. This paper introduces two new concepts for higher order differential (HOD) which are control transform for the input and observation transform for the output. With these concepts, we found a new 6-round HOD characteristic using 8-th order differential. By close examination of byte-value, we found the reason for this HOD. If we use the new HOD characteristic, instead of 32-nd order differential for the attack to 7-round CLEFIA, we can reduce to data and computational complexity around 2^-23, 2^-15 of the conventional one, respectively.

Keywords

computational complexity; cryptography; differential equations; 32-nd order differential; 6-round saturation; 7-round CLEFIA; 8-th order differential; block cipher; byte-value; computational complexity; control transform; input transform; observation transform; peculiar higher order differential; word length 128 bit; Computational complexity; Data processing; Equations; Transforms; Vectors;

fLanguage

English

Publisher

ieee

Conference_Titel

Information Theory and its Applications (ISITA), 2012 International Symposium on

Conference_Location

Honolulu, HI

Print_ISBN

978-1-4673-2521-9

Type

conf

Filename

6400992