On (k,n)~*-visual cryptography scheme

摘要

Let P = {1,2,.... n} be a set of elements called participants. In this paper we construct a visual cryptography scheme (VCS) for the strong access structure specified by the set Γ_0 of all minimal qualified sets, where Γ_0 = {S : S is contained in p, 1 ε S and |S| = k}. Any VCS for this strong access structure is called a (k, n)~*-VCS. We also obtain bounds for the optimal pixel expansion and optimal relative contrast for a (k, n)~*-VCS.