Dynamical Selective Image Encryption Using Chaos

Image data has been increasingly generated by cameras as well as acquisition modalities. Image data is diverse and has different sensitive levels. Encryption algorithms for massive image data are required not only high confidential but also high speed. Sometimes, the trade-off between the speed and confidentiality of an encryption occurs for image data, and it can be obtained with selective image encryption. However, most of existing selective image encryption algorithms are with fixed values of parameters, as a consequence, the confidentiality is threatened from cryptanalysis methods. In this paper, the scheme of selective image encryption using chaos is proposed, in which its parameters are changed dynamically. Specifically, the diffusion is carried out with dynamically selected pixels, and on its varying number of significant bits. The permutation performs on blocks of selected pixels with varying size. Intuitively, the security of the proposed scheme is improved by dynamical selective of data for the encryption. The exemplar simulation shows the effectiveness of the proposed scheme with security analysis by means of testing entropy, and correlation between neighbor pixels. The amount of data to be encrypted is also measured in compared with existing selective image encryption.