数字电视多层加密机制研究及前端系统的实现

发布时间：2018-03-29 19:36

本文选题：数字电视　切入点：条件接收　出处：《福州大学》2014年硕士论文

【摘要】：随着科学技术的发展,模拟电视已经不再适合时代的潮流,数字电视开始走进了寻常百姓家。未来数字电视将取代模拟电视,实现更多样化的用户体验。而数字电视条件接收系统(Conditional Access System, CAS)是一种用户授权技术,是数字电视的关键技术之一。其对数字音视频信号加密,保证未授权用户无法观看特定节目,从而保障了授权用户的利益。在条件接收技术支持下,数字电视各项增值业务才能有效的开展,受到更多用户的青睐,确保了数字电视市场化。本课题设计条件接收系统多层密钥分配方案,研发一种实用可靠的数字电视前端CA系统,保证百万级用户的授权管理。本文先介绍数字电视和条件接收技术国内外发展现状,阐述了数字电视CAS框架及其工作原理和相关标准等,并对标准中相关内容做进一步分析；然后介绍了条件接收技术涉及的密码学理论,分析常用的加解密算法,并从中选择适合课题使用的算法；并简要介绍了条件接收的同密和多密方式；结合现今市面上常见的条件接收密钥加密体系,分析各种加密机制,结合各机制的优点提出了一种混合三四层密钥分配机制,并应用于本系统的设计与实现。同时采用用户寻址广播和优先队列策略,减小授权信息数据量和系统带宽负荷,使用户可以更迅速有效的接收到授权信息。本文还研究了DVB数字电视发送端加扰机同密同步器和加扰器,文章给出授权信息数据详细定义,在VC#环境下完成授权控制信息发生器ECMG和授权管理信息发生器EMMG两个软件编写,给出其与加扰机通信的实现流程分析和重要数据,并为将来系统扩展提供必要支持。完成了CA系统前端EMMG和用户管理系统SMS的接口设计,给出了流程设计结构和数据接口定义,设计了EMMG程序的主线程,实现了优先队列策略。最后完成系统测试工作。测试结果表明发送端两个软件工作稳定,顺利完成授权信息的产生、发送和密钥加密工作,并实现对用户分组授权效果。接收端授权机顶盒可以正常解密解扰,播放清晰流畅。
[Abstract]:With the development of science and technology, analog television is no longer suitable for the trend of the times. Digital television has begun to enter the homes of ordinary people. In the future, digital television will replace analog television. Digital TV conditional Access system (Cass) is a user authorization technology and one of the key technologies of digital TV. It encrypts digital audio and video signals. Ensure that unauthorized users can not watch specific programs, thus safeguarding the interests of authorized users. With the support of conditional access technology, digital television value-added services can be effectively carried out and favored by more users. This paper designs a multi-layer key distribution scheme of conditional access system, and develops a practical and reliable digital TV front-end CA system. Firstly, this paper introduces the development of digital TV and conditional access technology at home and abroad, expounds the CAS framework of digital television, its working principle and related standards, and makes further analysis on the relevant contents of the standard. Then it introduces the cryptographic theory involved in conditional access technology, analyzes the common encryption and decryption algorithms, and selects the suitable algorithms for the subject, and briefly introduces the homo- and multi-encryption methods of conditional access. Combined with the common conditional access key encryption system in the market today, this paper analyzes various encryption mechanisms, and proposes a hybrid three or four layer key distribution mechanism combining the advantages of each mechanism. It is also applied to the design and implementation of the system. At the same time, the user address broadcast and priority queue strategy are adopted to reduce the amount of authorization information and the system bandwidth load. This paper also studies the synchronous synchronizer and scrambler of DVB digital TV transmitter and scrambler, and gives the detailed definition of authorization information data. Under the environment of VC#, two software programs, authorization control information generator (ECMG) and authorized management information generator (EMMG), are written. The realization flow analysis and important data of communication between authorization control information generator and scrambler are given. The interface design of EMMG in front end of CA system and SMS of user management system is completed, the flow design structure and data interface definition are given, and the main course of EMMG program is designed. The first queue strategy is implemented. Finally, the system testing is completed. The test results show that the two software on the sender work stably, and successfully complete the generation of authorization information, transmission and key encryption. The receiver authorization set-top box can decrypt and descramble normally and play clearly and smoothly.
【学位授予单位】：福州大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN949.197;TN918.4

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