A grouped-scalable secret image sharing scheme

Abstract

This paper addresses the problem of sharing the secret image among several groups with different priorities, resulting in a scheme of grouped-scalable secret image sharing. Our scheme is based on the concepts of bit-plane decomposition and Shamir's (k,?n)-threshold scheme: first, the secret image is decomposed into several subimages of different quality; second, each subimage is shared to generate shadows which are then embedded into the corresponding cover image by steganography, generating a group of stego images. The stego images in the same group are distributed to some specified participants with the same priority. At the receiver side, each subimage can be reconstructed only if more than k different shadows of the same group are provided, while the cooperation of fewer than k participants in each group or more than k participants from different groups cannot obtain anything about the subimage. Scalable recovering of the secret image is achieved when different groups offer their restored subimages. The lossless restoration of the secret image and cover images can be achieved when all of the subimages are available. The experimental results show the superiority of our scheme for grouped-management applications of secret images.