Image encryption based on discrete chaotic maps
Fan Chun-xia · Optics and Precision Engineering · 2004
Discrete chaos is used to generate cipher systems because it is easy to create, sensitive to initial value and similar to white noise of statistical nature. A quasi-Feistel network algorithm is designed using discrete chaotic maps for image encryption/decryption. All secret keys of the algorithm are generated by different chaotic maps, and this improves difficulty of decryption. Permutation and substitution consist of SP networks with good cipher performance. Permutation is also controlled by cipher to improve algorithm complexity. Safety is enhanced by the output of encryption which strongly depends on nonlinear coupled secret keys. All of white text is encrypted during each iteration of quasi-Feistel network, and this improves the encryption efficiency. Finally, a simulation test is conducted by taking the image Pout in Matlab as an example, and the simulation results show that the algorithm proposed possesses perfect safety and efficiency.