ИСТИНА

This study examines the properties of Boolean functions related to ensuring the resistance of the filter generator to the key recovery method, based on the so-called planar approximations. The problem of the existence of an «ideal» function, balanced on all possible planes, is considered. The weight distribution of Boolean functions on planes of different dimensions is studied: the number of planes on which the function is not balanced and the weight of the function on planes of a given dimension are estimated. In particular, the study presents all possible sets of values of the specified parameters for functions of 5 variables.