Frameproof codes against limited coalitions of pirates

Abstract

If Γ_p is a p-ary code of length n and a,b and c are three codewords, then e is called their descendant if e_i∈{a_i,b_i,c_i} for i=1,…,n. We are interested in codes Γ_p with the property that for any three codewords their only descendant codewords are themselves: this forbids a coalition of three users, given codewords a,b and c from framing a fourth user given the codeword e.