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

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. (C) 2020 Elsevier B.V. All rights reserved.