利用随机数序列加密视频变长码字的新方法  

A novel method to encrypt video variable length coding codeword by random number sequences

作　　者：杨志云[1] 陈琳[2] 李伟[1] 徐正全[1] 

机构地区：[1]武汉大学测绘遥感信息工程国家重点实验室,湖北武汉430079 [2]长江大学计算机科学学院,湖北荆州434023

出　　处：《华中科技大学学报（自然科学版）》2007年第3期8-11,共4页Journal of Huazhong University of Science and Technology(Natural Science Edition)

基　　金：国家重点基础研究发展计划资助项目(2006CB303104);湖北省科技攻关计划资助项目(2004AA101C18);武汉市重点科技攻关计划资助项目(20031003021)

摘　　要：提出了一种随机改变熵编码码表来实现视频变长码字加密的方法.将熵编码码表中的码字按长度等特征分组,对视频内容信息事件序列做熵编码时,对应每一事件产生一个随机数确定其编码成同组内的哪一码字,随机数序列由二进制随机序列生成以保证随机性.该方法解决了密文出现非法变长码字的难题,保证密文格式兼容,不降低压缩率,达到序列密码的抗攻击强度且计算速度快10倍以上.实验证明密文画面不能理解,该算法适用于MPEG,H.26x及JPEG等主流编码信号.Video variable length eodewords were encrypted by randomly changed variable length coding table while each codeword was coded. The codewords were grouped into the table according to their length. While coding the video event stream, a random number corresponding to every event was generated to decide which codeword in its group the event should be coded to. The randomness of the number sequence was ensured by generated from binary system random sequence. The difficult problem of generating forbidden codewords was solved while enciphering video in the algorithm. It can completely keep video coding format compliance and compression ratio. It has the same anti-attack strength as direct stream cipher method while its speed is over ten times faster than the latter to meet real-time requirement. The experiments show that the cipher pictures are fully disguised. The method can be applied to MPEG, H. 26x, and JPEG signal, and can be made as a separate modular.

关 键 词：视频加密 变长码字 改变变长码表 随机序列 

分 类 号：TP309[自动化与计算机技术—计算机系统结构] TP393[自动化与计算机技术—计算机科学与技术]