Cryptanalysis and Improvement of Chaos-Based Image Encryption Scheme with Circular Inter-Intra-Pixels Bit-Level Permutation

A novel chaos-based image encryption scheme has been proposed recently. In this scheme, redundancies of the Fridrich’s structure were reduced significantly via a new circular inter-intra-pixels bit-level permutation strategy. However, we proved that the original encryption scheme is vulnerable to the known/chosen-plaintext attacks. Both the permutation and diffusion phases have been improved to enhance the security of the original scheme. By shifting each row of the plain image randomly, known-plaintext attacks could be resisted. Furthermore, by appending double crossover diffusion to the end of the original scheme, chosen-plaintext attacks lost their efficacies. Simulation results demonstrated that the improved encryption scheme outperforms the original one.