Differential-Multiple Linear Cryptanalysis

Abstract

Differential-linear cryptanalysis was introduced by Langford et al in 1994. After that, Biham et al proposed an enhanced differential-linear cryptanalysis in 2002. In this paper, we present an extension to the enhanced differential-linear cryptanalysis, called differential-multiple linear cryptanalysis, in which a differential characteristic can be concatenated with multiple linear characteristics to derive a differential-multiple linear distinguisher. Furthermore, we introduce a technique about how to find a differential-multiple linear distinguisher based on a differentiallinear distinguisher for Feistel and SPN block ciphers. For illustration, this extension is applied to describe a differential-multiple linear distinguisher for 7-round DES, and then the best-known key recovery attack on 9-round DES is presented based on the differential-multiple linear distinguisher. As a matter of fact, our work is a new attempt to concatenate a differential characteristic with multiple linear characteristics to derive a new cryptanalytic tool which may be helpful to analyze a variety of block ciphers including Feistel and SPN schemes.