A combination of color-black-and-white visual cryptography and polynomial based secret image sharing

Abstract

A new (k,n) threshold secret image sharing scheme with two decoding options is introduced in this paper. The proposed scheme combines color-black-and-white visual cryptography scheme (CBW-VCS) and polynomial based secret image sharing (PSIS) together, to offer stacking-to-see decryption and lossless image reconstruction. To construct the color shares, a general (k,n) threshold CBW-VCS is firstly given. A grayscale secret image is converted to a p-radix image and a binary image. The p-radix image is encrypted by the (k,n) PSIS under mod p operation, and n p-radix shadows are obtained. Then, a color share generation algorithm with data embedding is proposed to construct n color shares. Theoretical analysis and sufficient experiments are provided to show the effectiveness and advantages of the proposed scheme.