A New Algorithm for Enumerating 1st-order Correlation-immune Function

As an important metric index for evaluating the performance of cryptosystem against correlation attack,the correlation-immune function is widely applied in computer security practice. The intrinsic properties of the fixed order characteristic matrix for 1st- order correlation- immune function are analyzed,and a new method for constructing 1st- order correlation- immune function is proposed. Based on this method and by combining exhaustion and statistics methods,a quick enumeration algorithm of six- variables1st- order correlation- immune function is designed,the number of six- variables 1st- order correlation immune function is given,and the computing complexity is as low as O(222),thus the efficiency of the enumeration for 1st-order correlation-immune function is greatly improved.