Vectorial Boolean functions are usually called Substitution Boxes (S-Boxes) and are used as basic component of block ciphers in Cryptography. The ciphers that are Substitution-permutation networks use bijective S-Boxes i.e., Boolean permutations. S-Boxes with low differential uniformity and high nonlinearity are considered as cryptographically strong. In this paper we study some properties of S...

Block ciphers are widely used in modern cryptography. Substitution boxes (S–boxes) are main elements of these types of ciphers. In this paper we propose a new method to create S–boxes, which is based on application of Cellular Automata (CA). We present the results of testing CA-based S–boxes. These results confirm that CA are able to realize efficiently the Boolean function corresponding to cla...

Most modern block and stream ciphers can be expressed as certain arrangement of Vector Boolean Functions. Thus, in the context of block and stream ciphers’ design (mainly in S-boxes and combining functions respectively), it is essential to define criteria which measure the cryptographic strength of Boolean Functions and Vector Boolean Functions. Ideally, some of the following requirements must ...

the strong ground motions recorded during the 2002 avaj earthquake have been used to estimates wave attenuation, qβ, and spectral decay parameter, κ, for the avaj region. qβ for shear wave is estimatedas a function of frequency in the range of 0.6- 18 hz. the results show that qβ increases with frequency in theform of qβ=62.7 f 0.9. our estimates are within the estimated range for different par...

Substitution boxes with thorough cryptographic strengths are essential for the development of strong encryption systems. They are the only portions capable of inducing nonlinearity in symmetric encryption systems. Bijective substitution boxes having both high nonlinearities and high algebraic complexities are the most desirable to thwart linear, differential and algebraic attacks. In this paper...

This paper presents a simple yet e ective method for transforming Boolean functions that do not satisfy the strict avalanche criterion SAC into ones that satisfy the criterion Such a method has a wide range of applications in designing cryptographically strong functions including substitution boxes S boxes employed by common key block encryption algorithms The rst author was supported in part b...