A novel image encryption scheme based on conservative hyperchaotic system and closed-loop diffusion between blocks

• Published in: Signal processing Vol. 171; p. 107484
• Main Authors: Zhou, Minjun, Wang, Chunhua
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.06.2020
• Subjects: Closed-loop diffusion; Conservative hyper-chaotic system; Image encryption; Inter-block; Image encryption; Closed-loop diffusion; Inter-block; Conservative hyper-chaotic system
• ISSN: 0165-1684; 1872-7557
• DOI: 10.1016/j.sigpro.2020.107484

•We firstly use a 5-dimensional conservative hyper-chaotic system to generate key streams for image encryption.•Compare to dissipative chaotic system, the conservative hyper-chaotic system we used has no attractor, thus can avoid the reconstructing attacks.•We propose a closed-loop diffusion mechanism between blocks dependent on both plaintext and ciphertext (CDMBDPC) for the first time. Different to the existing open-loop diffusion scheme, our closed-loop diffusion scheme can greatly improve the reliability of encryption system. In addition, our closed-loop diffusion mechanism implements the complete diffusion process of encrypting the first plaintext pixel block to encrypting the last pixel block and then updating the first ciphertext block.•To resist reconfiguration attack and statistical attack, the chaotic system used to generate pseudorandom sequences can't be refactored and key streams of an encryption model need to be random. Using the 5d conservative hyperchaotic system, we design a new chaos-based encryption algorithm with random key streams, and a closed-loop diffusion mechanism is designed in the encryption model to enhance the encryption reliability.•The image encryption scheme is sensitive to both the plain image and the cipher image.•The experimental results show that the proposed encryption algorithm has excellent security and reliability compared with exiting algorithms. Dissipative chaotic systems have been widely used in digital image encryption schemes in the past 20 years. However, compared to conservative chaotic systems, the dissipative chaotic systems have attractors thus attacker can reconstruct the chaotic systems by reconstructing the attractors. Therefore, the conservative chaotic systems are more suitable in chaos-based encryption system because they have no attractors thus can avoid the reconstructing attacks. Based on this, an image encryption scheme based on conservative hyper-chaotic system and closed-loop diffusion between blocks is proposed in this paper. On the one hand, the conservative hyperchaotic system has strong pseudo-randomness and anti-reconstruction attack property. On the other hand, different from the existing closed-loop diffusion schemes which change pixel values one by one until the last pixel value is changed, the proposed closed-loop diffusion method cannot only generate the first ciphertext and other ciphertext blocks but also update the first ciphertext block using the other generated ciphertext block information. In addition, the key streams are related to plaintext and ciphertext. Consequently, the key, plaintext and ciphertext form an organic whole to ensure the sensitivity of the encryption system. Moreover, simulation results and analysis show that the encryption scheme has strong security and excellent performance.