根據對圖像加密技術的分析，提出了對加密圖像置亂度進行評價的若干參數，這些參
數包括：信息熵、灰度平均變化值和圖像相似度。最后利用這些參數對圖像加密算法進行了模擬實驗分析及安全性評價。模擬試驗及分析結果表明，給出的幾個評價參數是實用的、有效的，可以用來對基于圖像加密算法的置亂度及安全性能進行綜合評價。
關鍵詞：置亂度；信息熵；安全性分析；灰度值
Abstract: Based on the analyses of image encryption, some parameters such as the percentage of the information entropy, the average of pixel grey-scale values change 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.
Key words: scrambling criterion; information entropy; analysis of security; grey-scale value