New Image Encryption Algorithm Based on Cascade Chaos System

摘要

As cascade chaos can enhance initial condition sensitivity of chaos mappings and security of chaotic pseudo-random sequences, a new image encryption algorithm is design based on cascade chaos. The algorithm is composed of three stages. The first stage is image scrambling based on chaotic weighted sampling theory and sorting transformation. The cascade chaotic interval sampling sequence is used into image scrambling, and in the second stage, the remaining values after interval sampling of cascade chaotic sequence are transformed to generate the final key matrix. The third stage is double diffusions utilized with the final key matrix. Key space, the pixels distribution characters, correlation coefficients, entropy, the ability to resist differential attack and the key sensitivity are simulated and analyzed. The simulation results prove that the proposed image encryption scheme possesses robust security features of large key space, fairly uniform distribution, and almost ideal entropy. Especially it has high sensitivity to both key and plaintext.