In this paper the decomposition formula of Walsh spectrum of boolean functions is used to construct a class of nonlinear resilient functions. § 1 Introduction A (n ,m,t)-resilient function (fl,. • • ,f.~) is an m-dimension t-th order correlation immune and balanced vector function. The concept was introduced firstly by Chor, et al. ~13 Resilient functions were originally applied respectively to the generation of random strings in presence of faulty processors and to key distribution especially for quantum cryptography. Several other applications afterwards emerged and the theory of resilient functions is now almost omnipresent in cryptography and communication. Researchers have concentrated themselves on linear resilient functions, but recent advances in cryptanalyses show that these functions cannot resist the best affine approximation (BAA) attack. So many researchers pay attention to investigate highly nonlinear resilient functions. E2-43 In [-23, it gives a method to construct new resilient functions by permutations, but its application is difficult. In [33 and E43, the constructions of balanced and correlation immune functions are introduced mainly by the composition of maps. In this paper we give some new construction methods of resilient functions on the basis of the decomposition formula of Walsh spectrum of a class of boolean functions. The resilient functions constructed in this paper have higher algebraic degrees and higher nonlinearity. The results are easily applied and can be extended to field Fp or ring Z~. §
The Definition and Equivalent Condition of Resilient FunctionGiven a sample space O=GF"(2) and a a algebra F= {A:ACO}, we have a probability measure over a measurable space (g~,F) satisfying