A (n, n) threshold non-expansible XOR based visual cryptography with unique meaningful shares

- A (n, n) threshold non-expansible XOR based visual cryptography with unique meaningful Shares has been proposed in this article for securing media information prior to outsourcingto cloud data centers.
- The secret media information is obscured into multiple meaningful shares without any pixel expansion, share alignment problem, contrast loss, explicit codebook requirement, and limitation on number of participants.
- The recovery of the secret media information is lossless at the receiver end that makes it suitable for applications that comprise of sensitive information.
- Outsourcing media information into meaningful shares reduces the vulnerability of the scheme to cryptanalysis as compared to random shares. In case of attacks at the cloud data centers, the altered regions can be detected by the scheme.

Cloud-based multimedia systems are attracting end users with high end infrastructure resources and enormous storage facilities. However, there persists a high chance of leakage of sensitive information if outsourced to the remote cloud servers without encryption. In this article, a secure way of obscuring the information based on XOR based Visual Cryptography (VC) has been proposed. It obscures the secret information into multiple meaningful shares prior to outsourcing which reduces the vulnerability of random looking shares to cryptanalysis. The scheme also overcomes the problems existing in the traditional VC schemes like pixel expansion, share alignment problem, contrast loss, explicit codebook requirement, limitation on number of participants and lossy recovery of the secret. Proposed scheme ensures perfect recovery of the secret with high boost in contrast at the authentic entity end. Three novel algorithms have been proposed for generation of basis matrices, generation of random shares and conversion of random shares to meaningful shares to achieve this objective. The visual quality of the meaningful shares and the recovered secret image is quite good as evaluated by various objective error metrics. Comparative results based on various aspects of visual cryptography prove the efficiancy of the proposed approach over existing state-of-the-art approaches.