In one dimension, there is essentially just one binomially distributed statistic, bias or correlation, for testing correctness of a key bit in Matsui's Algorithm 1. In multiple dimensions, different statistical approaches for finding the correct key candidate are available. The purpose of this work is to investigate the efficiency of such test in theory and… (More)
— In this paper, a multidimensional Walsh transform is used to obtain a characterization of vector-valued bent function in terms of the value distributions of the translates of the function by linear functions.
In the paper we studied different methods to extend Matsui's Alg. 2 to multiple dimensions. The efficiency of the methods were compared by the " advantage " (Selçuk). This presentation will focus on the method based on the log-likelihood ratio.
Various authors have previously presented different approaches how to exploit multiple linear approximations to enhance linear cryptanalysis. In this paper we present a new truly multidimensional approach to generalise Matsui's Algorithm 1. We derive the statistical framework for it and show how to calculate multidimensional probability distributions based… (More)
Biryukov, et al., showed how it is possible to extend Matsui's Algorithm 1 to find several bits of information about the secret key of a block cipher. Instead of just one linear approximation, they used several linearly independent approximations that were assumed to be statistically independent. Biryukov, et al., also suggested a heuristic enhancement to… (More)
In this paper, we present a new technique for Matsui's algorithm 2 using multidimensional linear approximation. We show that the data complexity of the attack can be reduced significantly by our method even when the linear hull effect is present. We apply our method to the key recovery attack on 5-round Serpent and demonstrate that our attack is superior to… (More)
In this article, the theory of multidimensional linear attacks on block ciphers is developed and the basic attack algorithms and their complexity estimates are presented. As an application the mul-tidimensional linear distinguisher derived by Cho for the block cipher PRESENT is discussed in detail.
Linear cryptanalysis and linear approximation methods in general are among the most important cryptanalysis methods of symmetric ciphers and their components. Recently, these methods have been extended to efficiently exploit multiple linear approximations simultaneously. It is known that high nonlinearity of Boolean functions and S-boxes is a desirable… (More)
The SOSEMANUK stream cipher is one of the finalists of the eSTREAM project. In this paper, we improve the linear cryptanalysis of SOSEMANUK presented in Asiacrypt 2008. We apply the generalized linear masking technique to SOSEMANUK and derive many linear approximations holding with the correlations of up to 2 −25.5. We show that the data complexity of the… (More)