An Image Encryption Arithmetic Base on Chaotic Sequences
Xiao Zhang · 2003
Chaotic sequences have several good properties , such as the ease of their generation, their sensitive dependence on its initial parameters, and specially white noise alike, at the same time it can be reproduced precisely based on the initial condition, and their discrete mapping sequences have a same property.Because of these good properties, chaotic system can be used to image encryption and image preprocessing. In this paper, image encryption arithmetic is proposed based on chaotic system. First, based on the key (initial parameter is the key, here), the chaotic sequences can be generated based on key, then it is mapped to the discrete 2 K value sequences, according to the discrete sequence, gray value of pixel is modified randomly, it is obvious that if attacker dose not know the key, the encrypted image will be looked like white noise and can not be rebuilt. There are many image encryption methods, and different arithmetic gets different results, but up to now there is no suit way to evaluate the result of image encryption. Based on image local variance and human vision system, an efficient definition of encryption degree is proposed. Preliminary results are satisfactory, and security of image completely depend on the key, slight error key results a different result. Hence, it can be used to encrypt image data.