Abstract: This paper presents a self-adaptive image encryption algorithm based on hyper-chaotic system. Firstly, the hyper-chaotic sequences which are pretreated are transformed according to the plaintext pixel information that result in both key sensitivity and plaintext sensitivity; then, the last encrypted pixel is used to produce intermediate key through nonlinear operation to encrypt the next pixel adaptively, until all pixels are encrypted completely; finally, the simulation analyses are performed using statistical property, anti-differential attacks, key sensitivity and key space and algorithm efficiency. Experimental results show that the algorithm is secure and efficient.

Key words: hyper-chaotic system, image encryption, self-adaptive image encryption