On bent and highly nonlinear balanced/resilient functions and their algebraic immunities

Abstract

Since the introduction of the notions of nonlinearity in the mid-70's (the term has been in fact introduced later), of correlation immunity and resiliency in the mid-80's, and of algebraic immunity recently, the problem of efficiently constructing Boolean functions satisfying, at high levels, one or several of these criteria has received much attention. Only few primary constructions are known, and secondary constructions are also necessary to obtain functions achieving or approaching the best possible cryptographic characteristics. After recalling the background on cryptographic criteria and making some general observations, we try to give a survey of all these constructions and their properties. We then show that a nice and simple property of Boolean functions leads to a general secondary construction building an n-variable function from three known n-variable functions. This construction generalizes secondary constructions recently obtained for Boolean bent functions and also leads to secondary constructions of highly nonlinear balanced or resilient functions, with potentially better algebraic immunities than the three functions used as building blocks. © Springer-Verlag Berlin Heidelberg 2006.