Secret image sharing based on cellular automata and steganography

Recently Lin and Tsai [Secret image sharing with steganography and authentication, The Journal of Systems and Software 73 (2004) 405–414] and Yang et al. [Improvements of image sharing with steganography and authentication, The Journal of Systems and Software 80 (2007) 1070–1076] proposed secret image sharing schemes combining steganography and authentication based on Shamir's polynomials. The schemes divide a secret image into some shadows which are then embedded in cover images in order to produce stego images for distributing among participants. To achieve better authentication ability Chang et al. [Sharing secrets in stego images with authentication, Pattern Recognition 41 (2008) 3130–3137] proposed in 2008 an improved scheme which enhances the visual quality of the stego images as well and the probability of successful verification for a fake stego block is 1/161/16.In this paper, we employ linear cellular automata, digital signatures, and hash functions to propose a novel (t,n)(t,n)-threshold image sharing scheme with steganographic properties in which a double authentication mechanism is introduced which can detect tampering with probability 255/256255/256. Employing cellular automata instead of Shamir's polynomials not only improves computational complexity from O(nlog2n) to O(n)O(n) but obviates the need to modify pixels of cover images unnecessarily. Compared to previous methods [C. Lin, W. Tsai, Secret image sharing with steganography and authentication, The Journal of Systems and Software 73 (2004) 405–414; C. Yang, T. Chen, K. Yu, C. Wang, Improvements of image sharing with steganography and authentication, The Journal of Systems and Software 80 (2007) 1070–1076; C. Chang, Y. Hsieh, C. Lin, Sharing secrets in stego images with authentication, Pattern Recognition 41 (2008) 3130–3137], we use fewer number of bits in each pixel of cover images for embedding data so that a better visual quality is guaranteed. We further present some experimental results.