An Image Encryption Scheme Based on Hyper Chaotic System and DNA With Fixed Secret Keys

A novel image encryption scheme combining the 5D hyper chaotic system and DNA technology is proposed in this paper. The proposed scheme is related to the plaintext and external secret key, which does not need to manage the huge amounts of dynamic secret keys and does not to design synchronization method as the one-time-pad encryption scheme. The proposed scheme consists of four parts: pixel-level diffusion, pixel-level permutation, DNA-level diffusion and second permutation. In pixel-level diffusion process, chaotic sequences iterated by 5D hyper chaotic system with initial values (which are set as secret keys) are used to rewrite the pixel values of plaintext image and they are also used to generate second permutation rule. Then the pixel-level permutation rules are obtained by chaotic system with modified initial values that are related to the plaintext image and external secret key. In this case, the permutation rules are different when the plaintext images are different. In the DNA-level diffusion process, we select a part of pixel values of the pixel-level permutated image and external secret key to generate key streams used in DNA-level diffusion process. In this case, the decryption part can obtain the selected pixel values during the decryption process, which avoids transmitting huge secret keys and synchronizing them with plaintext images. In the second permutation, we rearrange the position of the selected pixel values, which can enhance the security of the proposed scheme. Finally, experimental results and security analysis verify that the proposed scheme can achieve good encryption effect and resist various attacks.