Image encryption algorithm with compound chaotic maps

This paper proposes a novel image encryption scheme based on two even-symmetric chaotic maps and a skew tent chaotic map. In the permutation process, a P-box produced by sorting an even-symmetric chaotic sequence is applied to shuffle the positions of all image pixels. In the diffusion process, both even-symmetric chaotic map and skew tent map are used to generate the key stream. The pixels in the permuted image determine which of two even-symmetric chaotic maps is iterated for next byte in the keystream each time, so the keystream is closely related to the plain image. The performance and security of the proposed method are evaluated thoroughly histogram, correlation of adjacent pixels, information entropy and sensitivity analysis. Results are encouraging and suggest that the scheme is reliable to be adopted for the secure image communication application.