In this paper, a novel image encryption scheme has been proposed using pixel-level scrambling, bit-level scrambling and DNA encoding. Firstly, initial conditions of 5-D hyperchaotic system are computed and chaotic sequences are generated. Then pixel-level scrambling and bit-level scrambling are implemented to permute the plain image. Permuted image and generated pseudo random sequence are executed decomposition operation in order to enhance security. DNA encoding, DNA XOR operation and DNA complementary rules are also adopted to improve the security of the cryptosystem. Experiments results and theoretical analysis show that the proposed scheme is secure enough and can resist known plain text attack, statistical attacks and differential attacks. It is suitable for practical application.

Image encryption is an effective method for protecting private images during communication. In this paper, a novel image encryption method is proposed based on a 5D hyperchaotic system. Since a 5D hyperchaotic system can generate more complex dynamic behavior than a low-dimensional system, it is used in this paper to generate pseudorandom number sequences. The generated sequences are processed to obtain new sequences. The randomness of the new sequences is improved by recombination and rearrangement. The experimental results and theoretical analysis show that the method possesses a large key space and can resist differential attacks, statistical analysis, entropy analysis, clipping attacks and noise attacks. Therefore, it is very secure and can be used for secure communication.

With the development of communication techniques and the Internet, how to protect private image transmission on the Internet has been a research highlight. Scholars have proposed different kinds of image encryption algorithms. Some of them are not secure enough. A novel cryptosystem is presented which is based on a 6D hyperchaotic system and random signal insertion. To enhance the dynamic performance of the hyperchaotic system, insert some random signals into the system variables during iteration. The sum value of all plaintext pixels is used to produce the initial values of the system. Thus, the proposed cryptosystem is closely related to the plain image. Split a pixel into two equal parts and form a larger matrix. Scrambling, cycle shift, and diffusion are operated on the new matrix. Finally, we obtain the encrypted image. The simulation results reveal that the proposed method has a very large key space, high key sensitivity and robustness, and is able to resist many different attacks. It is more secure than many other image encryption schemes.

An image encryption technique has been proposed using deoxyribonucleic acid (DNA) operations and chaotic map in this scheme. First, initial conditions of row encryption and column encryption are calculated. Then, a two-dimensional sine iterative chaotic map with infinite collapse (ICMIC) modulation map (2D-SIMM) is adopted to produce chaotic sequences. Extended exclusive OR (XOR) is executed to enhance security. A mask matrix is produced by 2D-SIMM. It performs XOR operation with the DNA-encoded matrix. Finally, the revised DNA-encoded matrix is performed two-by-two DNA complementary rules and executed DNA decoding to obtain the cipher image. Experiment results prove that the proposed scheme is secure enough and can resist various attacks.