Extended visual cryptography for general access structures using random grids

Noise-like random shares successfully hide secret images, but suffer management problem: dealers themselves cannot differentiate between the shares. This problem is solved by the extended visual cryptography scheme that stamps different innocent looking cover image on each share. In this paper, we propose an extended visual cryptography scheme using random grids which can accommodate general access structures. Random grids help us get rid of pixel expansion and extensive codebook designs. The experimental results validate the correctness of the algorithms from security perspective.