Finding invertible permutation functions

hi, I am looking at single cycle, invertible permutation functions of the form x -> x+ (x^2 V C) (mod 2^n), where V is a bitwise OR and C is a special constant. This function is as given in the url below http://citeseer.ist.psu.edu/klimov02new.html Would like to find the inverse permutation function for it but the paper only shows that the above function is provably invertible. Are there any construction methods for finding inverse permutation function, for a single cycle invertible function f? Thanks, Sarad. ____________________________________________________________________________________ Never miss a thing. Make Yahoo your home page. http://www.yahoo.com/r/hs