Novel Technique in Linear Cryptanalysis

Non-Linear Approximations in Linear Cryptanalysis

By considering the role of non-linear approximations in linear cryptanalysis we obtain a generalization of Matsui’s linear cryptanalytic techniques. This approach allows the cryptanalyst greater flexibility in mounting a linear cryptanalytic attack and we demonstrate the effectiveness of our non-linear techniques with some simple attacks on LOKI91. These attacks potentially allow for the recove...

Experimental Non-Linear Cryptanalysis

Enhancing Differential-Linear Cryptanalysis

Differential cryptanalysis analyzes ciphers by studying the development of differences during encryption. Linear cryptanalysis is similar but is based on studying approximate linear relations. In 1994, Langford and Hellman showed that both kinds of analysis can be combined together by a technique called differential-linear cryptanalysis, in which the differential part creates a linear approxima...

Linear Cryptanalysis of DES

The main goal of this diploma work is the implementation of Matsui’s linear cryptanalysis of DES and a statistical and theoretical analysis of its complexity and success probability. In order to achieve this goal, we implement first a very fast DES routine on the Intel Pentium III MMX architecture which is fully optimised for linear cryptanalysis. New implementation concepts are applied, result...

Chapter 1 - Linear cryptanalysis

Linear cryptanalysis was first introduced by Mitsuru Matsui in [12]. The cryptanalyst attempts to find a linear equation x1 ⊕ . . . ⊕ xi = y1 ⊕ . . . ⊕ yj in the input and output bits of some part of the cipher which holds true with probability sufficiently different to 0.5. “Sufficiently different” means that for a known-plaintext attack on a feasible number of known plaintexts, when the corre...