Digital Image Encryption And Encryption Algorithm Performance Evaluation

Digital image as an important carrier of information, its security has drawn increasing attention. Image encryption methods and image encryption performance evaluations are two research contents of image safety,this artical mainly studies the two major research contents.In image encryption methods, aim at traditional encryption algorithms exist for periodic problem, using chaos system put forward a digital image scrambling encryption algorithm based on circular shifting with non-periodic; For the security of encryption algorithm unsafe and key space small, construct two digital image encryption algorithms based on permutation; For the security of low-dimensional chaos systems is bad, put forward two high-dimensional chaos systems and prove the mathematical natures of the new systems.In encryption algorithm performance evaluation, after theoritical analyse one image scrambling degree evaluation method based on cross-entropy, put forward an improve method for evaluation algorithm performance; Base on a measure of information entropy in the probability distribution of two similar levels of Bhattacharyya, put forward an image scrambling evaluation method based on probability distance. Experimental results show that the evaluation methods are effective.