An improved scheme for secret image sharing

Secret image sharing is a technique used to secure digital images against disclosure and tampering. In this paper, we analyze the security of the secret image sharing scheme proposed by Thien and Lin and expose its weakness. Their method uses a permutation step which requires a key. The security of their method is dependent more on this key rather than on the unconditional security characteristics of the secret sharing scheme. We propose an improved scheme for the secret image sharing by removing the permutation step. The core idea of our scheme is to divide the secret image into k sections and use the pixel values from these sections as the coefficients of the polynomial used for creating shares in Shamir´s secret sharing scheme. The security analysis and experimental results are presented to demonstrate the utility of our method.