Essential visual cryptographic scheme with different importance of shares

Abstract

Essential secret image sharing scheme allows some participants own special privileges with different importance of shares. The beauty of visual cryptographic scheme (VCS) is that its decoding is based on stacking and human visual system (HVS) without cryptographic computation. In this paper, for the first time essential and non-essential VCS (ENVCS) is introduced based on pre-existed (k, n) VCS. In the proposed (k0, n0, k, n) ENVCS, we generate the secret image into n shares which are classified into n0 essential shares and n - n0 non-essential shares. In the decoding phase, in order to reveal secret we should collect at least k shares, among which there are at least k0 essential shares. Experiments are conducted to evaluate the security and efficiency of the proposed scheme.