Sharing a Secret Image in the Cloud Using Two Shadows

In this paper, we present a novel (2, 2) reversible secret image sharing scheme. Our scheme permits secret messages to be shared with two participants by splitting the marked encrypted image into two shadows. The secret messages can be reconstructed if two participants collaborate with each other. The proposed scheme chooses suitable binary blocks of a cover image in which to embed the secret message and divides those blocks into two shadow blocks by executing a logical operation with all of the other binary blocks, thereby producing two shadows. In the data extraction procedure, the secret messages and the cover image can be reconstructed by the logical operation of the corresponding binary blocks of the two shadows. A practical application is demonstrated by modeling our scheme as a reversible watermarking scheme in the Cloud. The experimental results indicated that the proposed method is reversible and that it can restore the image and watermark properly.