A Multi-threshold Secret Image Sharing Scheme

Secret sharing scheme is an important part of information security. As an extension of secret sharing, secret image sharing solves the problems that images are potentially modified or lost in transmission and storage efficiently such that the completeness and security of secret images is improved. In a (t, n) secret image sharing scheme, a dealer encrypts the secret image s into n shadow images such that each participant holds one shadow. Only t out of n participants with their shadows can cooperate to recover the secret image, while any t-1 or fewer participants cannot get any information about the secret image.In a multi-secret image sharing scheme, participants are able to share multiple secret images and each secret image can be reconstructed according to the corresponding access structure. Compared with a traditional secret image sharing scheme, a secret sharing scheme for multiple images has better efficiency in time and space. However, there are few schemes dealing with multi-secret image sharing, which can’t meet the demand of the people. In this paper, employing Chan and Chang’s multi-secret sharing, we propose a novel multi-threshold secret image sharing scheme, which can also be applied for any monotone access structure with a deletion procedure. This paper first describes the current research.on secret sharing schemes and secret image sharing schemes, and some basic concept and technology used in the area. Then we propose a perfect scheme for multi-secret image sharing. In the secret image sharing process, based on the generalized CRT, secret values are produced according to the associated access structures. The meaningful shadow images can be generated by embedding the secret values into a cover image using the quantization operation, and the secret image can be retrieved by a qualified subset of the shadow images without distortion. The experiments demonstrate that the proposed scheme is feasible and the quality of the shadow images is satisfactory.