Research On Scrambling-permutation Image Encryption Algorithm Based On Chaotic

With the fast development of computer technology and the Internet,smartphones and informatization become common very soon.During the transmission of information,as an important information carrier,digital images are more and more accepted by people,which leads to the issue of information security.Since digital images have large amount of data,high redundancy and strong correlation,most traditional encryption algorithms cannot meet the requirement of encrypting digital images because those algorithms are designed for encrypting text based data.Chaotic system,on the other hand,has been widely used in information security filed,because of its excellent initial value,parameter sensitivity,ergodicity and trajectory of unpredictability.In order to solve the issue of traditional cryptographic algorithms in encryption of digital image,scholars have proposed image encryption algorithms that are based on chaos and pixel scrambling-diffusion.However,with the development of cryptographic analysis and supercomputer techniques,low-dimensional chaotic systems have been proved to be insecure.In this paper,a typical encryption algorithm based on chaos and scrambling spread is analyzed and some shortcomings are discussed.Also,in order to eliminate these defects,the algorithm is improved by ways include: choosing a more complex high-dimensional chaotic system to generate pseudo-random sequence,and introducing ciphertext interspersed spread mechanism.Experimental analysis shows the optimization of improved algorithm,and some problems as well.In the process of scrambling,the characteristics of the images are not fully taken in consideration.Then an image encryption algorithm(BCC-IEA)based on hyper chaotic and bitwise cryptography is proposed,the core idea of which is treating each bit on a pixel equally.Without reducing the executing efficiency,a bit of a pixel is interchanged with other bits of other pixels as much as possible for sufficient scrambling.In addition,during the process of pixel value diffusion,the relationship between the key and plaintext is complicated,and the sensitivity of theciphertext to plaintext and key is enhanced.In the end,security test is done to analyze the sensitivity of key,correlation and information entropy for the proposed algorithm(BCC-IEA).And the experimental result shows that the algorithm has the ability to resist multiple attacks and verifies the security of the algorithm.