中文摘要：

为了解决现有的基于H．264的加密算法无法满足安全性和加密效率之间较好折衷的问题，提出两种基于感兴趣区域的H．264加密算法，将感兴趣区域的提取和基于熵编码的H．264加密算法相结合，只对提取出来的感兴趣区域进行加密．设计了一种基于人脸检测的加密算法，并通过修改模式选择算法，去掉了使得非人脸区域参考人脸区域的帧间宏块预测类型，解决了由帧间预测引起的人脸加密区域变形的问题．将运动对象的检测与提取和H．264的编码过程结合，设计了一种基于运动对象检测的H．264加密算法．实验结果表明，这两种加密算法能够在不降低算法安全性的情况下获得安全性和加密效率之间的较好折衷，可以满足实时应用的需求．

英文摘要：

In order to resolve the problem that the existed H. 264-based video encryption algorithms cannot obtain the tradeoff between security and encryption efficiency, two encryption algorithms are proposed based on the regions of interest in H. 264 video. These algorithms combine extraction of region of interest with entropy encoding algorithm and only encrypt the extracted region of interest macroblock. A face-detection encryption algorithm is put forward,in which the mode selection algorithm is modified so that the inter macroblock prediction type of face region＇s referring to non-face region is eliminated. Another algorithm extracts motive object and encrypts macroblocks which belong to motive object during encoding procedure. Experimental results demonstrate that the two proposed algorithms can obtain a good tradeoff between security and efficiency and can meet the need of real-time applications.