A system, method and program storage device tangibly embodying a program of instructions for determining whether to allow transmission of data from a source destined for a destination over a network, comprising: acquiring a string of a predetermined length in bits (L) from the data; partitioning the acquired string into a partition of phrases, each of the phrases in the partition being unique and having one or more bits; determining a number of phrases (N) in the partition; estimating a normalized complexity (C) for the Kolmogorov Complexity in the acquired string via.ident..times. ##EQU00001## and evaluating whether to allow transmission of the data based on a comparison of whether the normalized complexity estimate (C) is within a predetermined normal complexity estimate band.