Image Encryption Scrambling Performance Analysis

With the rapidly development of network and multimedia technology, more and more image data transfer on Internet. As the text data, the image data face the problem of security. In order to protect the privacy and to make the image data transfer more safely, the experts come up with a lot of schemes of image encryption. To use the schemes and to improve the technology of image encryption, it is very necessary to compare and analyse the algorithm of image encryption.In this thesis, the classical encryption method is reviewed and the methods of data encryption technology in recent years are summed up. Then some parameters such as the percentage of unchanged point, the information entropy, the average of pixel grey-scale values change, the r-m self-correlation of image and comparability of image are given to evaluate the image scrambling. At last using the parameters, the algorithm of image encryption is tested and the safety of the algorithm is evaluated.The simulation results of the experiment indicate that the parameters to evaluate scrambling criterion and the safety of image scrambling are useful and effective. What' s more , the experiment indicates that the safety is not good because of only using pixel- position scrambling technique to encrypt the image. Basing on the chaos system the result of image encryption is so good not only about the image correlation and scrambling criterion, but also about the entropy and the change the average of pixel grey-scale values. Because the image encryption is sensitive for the key, this method can be effectively used in the image encryption.