Invertible secret sharing: Using meaningful shadows based on Sorted Indexed Code

The need for secret sharing using meaningful shadow images is an important method to protect the transmitted data that does not attract the attention of adversary, which has become obvious in the past few years. The recovery of the cover image without any distortion and security of the embedded secret string efficiently needs to be addressed. This paper proposes an invertible (k,n) secret sharing scheme using meaningful shadow image based on Sorted Indexed Code (SIC) with high embedding capacity. The SIC helps to achieve better randomness between shadow images in terms of NPCR, the closeness of each objective assessment (i.e., PSNR, SSIM, NPCR, and UACI) between the shadows. Hence, by utilizing the SIC and polynomial based threshold secret sharing method the proposed scheme achieves an adequate visual quality of shadow images, complete recovery of the cover image, and increases the embedding capacity. The experimental results show the visual quality of image shares for camouflage purpose of steganography. The visual qualities of shadow images for the proposed scheme are validated through Peak-Signal-to-Noise Ratio (PSNR) and Structural Similarity Index Method (SSIM) analysis. Further, the security of the proposed scheme is analyzed using dissimilarity measures; Number of Pixel Change Rate (NPCR) and Unified Average Changing Intensity (UACI).