H.264/AVC作为新一代国际视频编码标准已经广泛应用于政治、军事、商业、教育、医疗等各行各业。但视频数据遭到恶意破坏、非法窃取以及数字媒体盗版等现象已经普遍存在，故对视频数据的安全性保护研究越来越受到人们的重视。视频数据具有数据量大、编码结构复杂、对实时性处理要求高的特点，并且视频数据在压缩编码后需要存储或传输，因此加解密算法必须结合编解码过程及实际应用环境来设计。
然而，众多现有视频加解密算法普遍存在三个方面的问题。一是加解密算法中所用混沌系统是基于实数域上进行的浮点运算，加解密双方会因计算机字长不同而产生加解密密钥流不同步的问题。二是加密算法会破坏语义格式信息，并且只能提供一个安全性级别。三是加密算法大都是基于视频编码层的研究，而对基于网络适配层的讨论较少。
针对上述问题，本文从信息安全的角度出发，以混沌密码学和视频压缩标准为理论基础，研究了视频数据的加解密算法。本文主要工作如下：
首先，采用广义猫映射和离散分段线性混沌映射构造了一种整数域混沌流密码序列发生器来克服数字化混沌的有效字长问题。通过理论分析，该混沌系统具有足够高的安全性。实验结果表明，该混沌系统具有良好的初值敏感性，由其产生的伪随机序列能够通过Golomb对序列随机性提出的三点假设检验，并且也能通过局部随机性统计检验。
其次，在视频编码层给出了一种质量可控并保持语义格式不变的视频混沌加解密方案。从加密效果上看，不同级别的加密对视频图像置乱程度是不一样的，因此能够满足不同场合对安全性级别的需求。从实验测试结果可知，该加解密方案对编解码速度的影响不超过3%，对压缩比的影响不超过4%，故能够满足实时性及对压缩比影响小的要求。针对该加解密方案，基于MFC平台，结合测试模型并利用动态链接库和多线程技术设计了H.264加解密软件系统。
最后，对H.264网络适配层进行了研究，详细分析了视频编码码流的封装格式，给出了基于应用层加密和基于网络层加密的系统框架，并基于网络层给出了一种基于码流分析的视频加解密方案，并对其性能进行了分析。

As a new generation of international video coding standard, H.264/AVC has been
widely used in political, military, commercial, education, medical care and some other
businesses.But the video was suffered from vandalism, illegal theft and digital media piracy, such as the phenomenon has been prevalent, so video data on the safety protection is receiving increasing attention. Video data has a lot of features which are large amount of data, complex coding structure and requirements of high real-time, and compressed video data is encoded in the required storage or transmission. Therefore, encryption and decryption algorithm must be designed to combine with the process of codec and the practical application of environment.
   However, many existing video encryption algorithm have three problems.Firstly, the using chaotic systems are based on floating-point operations on the real number field, both encryption and decryption will bring the problem of the key non-synchronous because of the computer word length different.Secondly, encryption algorithm will destruct video format, and can only provide a level of security. Thirdly,
encryption algorithms are based on the video coding layer, adaptation layer for network-based encryption algorithm little discussion on it.
Aiming at these issues, this article from the point of view of safety information, on the basis of chaotic cryptography and video compression standard, study the video of the encryption and decryption algorithm. Main task of this article are:
First of all, the use of generalized cat map and the piecewise linear chaotic map construct integer domain structure of a stream cipher sequence generator, this generator overcomes the chaos of the digital word length problem effectively. Through theoretical analysis, the chaotic system has high enough security. The experimental results show that the chaotic system has a good sensitivity of the initial value, and the pseudo-random sequence has a good pseudo-random property which can make three assumptions through Golomb and the local randomness statistical test.
Secondly, this paper presents a quality control and maintain the same semantic format chaotic encryption and decryption of video program at the video coding layer.From the encryption results, different levels of encryption is not the same as the degree of the video image scrambling,so it can be meet the various occasions on the security level of demand. From the test results experiment, we can see that the encryption and decryption program on the impact of encryption and decryption speed and the compression ratio have litter impact, it does not exceed 3% and 4%.So it is able to meet the requirements of real-time and less impactinn on compression ratio.In allusion to this encryption sheme, based on MFC-platform, combined with test model and used of dynamic-link library and multi-threaded, the thesis designed the encryption software system of H.264 technology.
Finally, the article research the H.264 network adaptation layer ,labor the encoded bit stream format of the package, give an encryption system framework which is based on the application layer and network layer ,and the video stream encryption and decryption programs based on a code-based Analysis to the network layer,and analysis the performance of the encryption scheme.