New Results on Pseudorandom Permutation Generators Based on the DES Scheme

We denote by ?k the permutation generator based on the DES Scheme with k rounds where the S boxes are replaced by random independant functions. We denote by |P1 - P1*|, (respectively |P1 - P1**|), the probability of distinguishing such a permutation from a random function (respectively from a random permutation) by means of a distinguishing circuit that has m oracle gates.