As a general rule, using secret sharing protocols, for any choice of n and k, you can split any illegal piece of information a into n pieces such that k of these pieces together can reconstitute a but <k pieces will not give any information about a. It is hard to tell to what extent an individual piece is illegal or not.

Related: http://www.madore.org/~david/misc/freespeech.html (does something similar using XOR, and discusses interesting uses of that kind of system).