Since the proposal of differential cryptanalysis and linear cryptanalysis in 1991 and 1993, respectively, the resistance to these cryptanalysis has been studied. In FSE2, Knudsen proposed a method of attacking block ciphers that used the higher order differential, and in FSE4, Jakobsen and Knudsen applied it to a cipher proposed by Nyberg and Knudsen. Their approach, however, requires large com...

We introduce KFC, a block cipher based on a three round Feistel scheme. Each of the three round functions has an SPN-like structure for which we can either compute or bound the advantage of the best d-limited adaptive distinguisher, for any value of d. Using results from the decorrelation theory, we extend these results to the whole KFC construction. To the best of our knowledge, KFC is the fir...

Recent block ciphers have been designed to be resistant against differential cryptanalysis. Nevertheless it has been shown that such resistance claims may not be as accurate as wished due to recent advances in this field. One of the main improvements to differential cryptanalysis is the use of many differentials to reduce the data complexity. In this paper we propose a general model for underst...

Recently, a new kind of Generalized Unbalanced Feistel Network, denoted as GUFN-n, is proposed by Choy et al. at ACISP 2009. The advantages of this structure are that it allows parallel computations for encryption and it can provide provable security against traditional differential and linear cryptanalysis given that the round function is bijective. For this new structure, the designers also f...

A robust and secure cryptosystem is an encrypting system that resists against all practical cryptanalysis methods such as statistical attacks, differential cryptanalysis and linear cryptanalysis. To prove the resistance against these attacks, the cryptosystem designer must carry out a list of robustness tests. Considering these constraints, we present in the current paper results of robustness ...

This paper considers a cryptanalytic approach called integral cryptanalysis. It can be seen as a dual to differential cryptanalysis and applies to ciphers not vulnerable to differential attacks. The method is particularly applicable to block ciphers which use bijective components only.

This thesis presents some novel results on the cryptanalysis and design of stream ciphers. The first part of the thesis introduces various stream ciphers design and cryptanalysis techniques. The second part of the thesis gives the cryptanalysis of seven stream ciphers. The properties of addition are exploited in the cryptanalysis of two stream ciphers: the differential-linear cryptanalysis agai...

The objective of this contribution is to introduce an analogue to the classical secret-key block ciphers, such as DES, IDEA or AES, in the nondenumerable setting, namely where cleartexts, plaintexts and keys are real numbers. The nonlinear part of traditional secret-key block ciphers, the S-boxes, is designed to provide confusion i.e. to resist to several kind of cryptanalysis such as algebraic...