Image Sharing Method Using Somewhat Homomorphic Encryption and Random Grid

In recent years, image sharing method has become a popular technique due to the characteristics of security and simplicity. However, pixel expansion and bad image contrast are two common disadvantages that must be improved. This paper proposes an image sharing method to improve the problems mentioned above. First, the homomorphic encryption is utilized to enhance the security of digital images. Then the algorithm of random grid is utilized to construct the non-expanded shares. Furthermore, performing XOR and modular operations can completely recover the original secret images. Experimental results show the effectiveness of the proposed method.