Abstract: An encryption algorithm which combined the process of MPEG video compressing with video encryption based on Lorenz chaotic system was put forward to deal with the security problem of video information. Three dimensional chaotic sequences of Lorenz system were used to encrypt DC, AC and motion vector coefficients during the compressing of I frame, B frame and P frame. The luminance information of I frame was encrypted among blocks by the chaotic sequence. The algorithm is secure and real-time because the encryption is done during the process of video compressing.

Key words: chaos, MPEG, encryption, Lorenz system

摘要： 为解决视频信息的安全问题，提出了一种利用Lorenz混沌系统，将加密过程融入到压缩过程的MPEG视频加密算法。利用Lorenz系统所产生的三维混沌序列，分别在I帧、P帧和B帧的压缩过程中，对DC、AC系数以及运动矢量进行混沌加密，并对I帧中的亮度信息以块为单位进行混沌置乱。由于加密在压缩过程中完成，该加密算法具有较好的实时性和较高的安全性。

关键词: 混沌, MPEG, 加密, Lorenz系统