Dynamic visual cryptography scheme on the surface of a vibrating structure

Dynamic visual cryptography scheme based on time-averaged fringes generated by Ronchi-type geometric moiré gratings on finite element grids is proposed in this paper. A single cover image is used to encode the secret image and is formed on the surface of a deformable structure. Time-averaged moiré fringes leak the secret when the structure is oscillated according to a predefined Eigen-shape. The envelope functions determining the motion induced blur of the Ronchi-type moiré grating depend on the characteristic features of the motion. And though harmonic oscillations do not result into a completely uniform time-averaged image of the Ronchi-moiré grating, initial phase scrambling and phase normalization algorithms are used to encode the secret in the cover image. Theoretical relationships between the amplitude of the Eigen-shape, the order of the not completely developed time-averaged fringe and the pitch of the deformable one-dimensional Ronchi-type moiré grating are derived

A Modified Multi-secret Visual Cryptography with Ring Shares

Abstract. A visual cryptography scheme encoding multiple secret images into two ring shares is proposed in this paper. In the secret sharing process, two shares are produced by the marked areas and the basis matrices of (2, 2)-VCS. Using ring shift right function, the secret images are recovered by stacking two shares. The security and contrast properties of the scheme have been proved. Compared with the previous ones, the scheme makes the number of secret images unlimited. Furthermore, the pixel expansion and the relative difference are improved greatly

Two-out-of-two color matching based visual cryptography schemes

International audienceVisual cryptography which consists in sharing a secret message between transparencies has been extended to color prints. In this paper, we propose a new visual cryptography scheme based on color matching. The stacked printed media reveal a uniformly colored message decoded by the human visual system. In contrast with the previous color visual cryptography schemes, the proposed one enables to share images without pixel expansion and to detect a forgery as the color of the message is kept secret. In order to correctly print the colors on the media and to increase the security of the scheme, we use spectral models developed for color reproduction describing printed colors from an optical point of view

A Reversible Steganography Scheme of Secret Image Sharing Based on Cellular Automata and Least Significant Bits Construction

Secret image sharing schemes have been extensively studied by far. However, there are just a few schemes that can restore both the secret image and the cover image losslessly. These schemes have one or more defects in the following aspects: (1) high computation cost; (2) overflow issue existing when modulus operation is used to restore the cover image and the secret image; (3) part of the cover image being severely modified and the stego images having worse visual quality. In this paper, we combine the methods of least significant bits construction (LSBC) and dynamic embedding with one-dimensional cellular automata to propose a new lossless scheme which solves the above issues and can resist differential attack and support parallel computing. Experimental results also show that this scheme has the merit of big embedding capacity