Image encryption algorithm based on hyper-chaotic system and dynamic S-box

Abstract

Chaos based image encryption algorithm is a research hotspot in multimedia security area. In this paper, a hyper-chaos based image encryption algorithm is proposed. Firstly, a new hyper-chaotic system is constructed and its dynamic characteristics are analyzed. The proposed hyper-chaotic system has bigger Lyapunov exponent than many classical hyperchaotic systems. Then this system is used to generate key-streams to permute and substitute the image pixels. In the encryption algorithm, a dynamic S-box is constructed to get good confusion effect. This S-box is based on the inverse operation in the algebraic structure Z 257 . Moreover, this inverse operation is embedded into an affine transformation to complicate the algebraic expression of the S-box and improve its security. The analysis results show that the proposed algorithm performs well.

Cryptanalysis and Improvement on an Image Encryption Algorithm Design Using a Novel Chaos Based S-Box

“…The results show that all entropy values are significantly closer to the ideal value eight, so the randomness is satisfactory. Besides, our improved scheme has better results than References [9,15,23]. Hence, our improved encryption scheme is more capable of resisting entropy-based attacks.…”

“…The information entropy of an encrypted image should be as close as possible to 8. The information entropy results of encrypted images by our improved scheme and schemes in References [9,15,23] are listed in Table 3. The results show that all entropy values are significantly closer to the ideal value eight, so the randomness is satisfactory.…”

“…Wang et al [8] designed S-boxes by chaotic Kent map and Logistic map and used the S-boxes for image encryption. Liu et al [9] constructed a dynamic S-box to enhance the image encryption effect. Khan et al [10] constructed a new S-box by using a random bit sequence generated by chaotic boolean functions and used the S-box for image encryption.…”

“…Recent cryptanalysis researches show that some chaos based image encryption algorithms are not secure enough. For example, the image encryption scheme in Reference [9] was broken by Zhang et al [20]. The image encryption scheme in Reference [21] was broken by Zhu and Sun [22].…”

A new image cryptosystem based on 2D hyper-chaotic system

“…MD hyper-chaotic systems with more complex dynamical characteristics than general chaotic systems were investigated [12,18,22]. Image encryption schemes based on hyper-chaotic systems were suggested to overcome the drawbacks existing in the cryptosystems with general chaotic systems [5,8,10,15,24]. Furthermore, image encryption schemes with hyperchaotic systems become popular.…”