Research And Implementation Of Content Protection System For Digital Interface

With the rapid development of multimedia and Internet,consumption of digitized content has become the main form of people using high-definition content.When the digitization of media content brings convenience to people,it also makes content easy to be illegally copied in the process of transmission to display devices through digital interfaces after reaching the terminal,which damages the interests of content providers and creators.The emergence of content protection system for digital interface effectively solves this problem.In recent years,consumer electronics for digital content have been widely used.Creation of digital content has been more convenient and distributed,and its value is also diversified,which raises new demands of diversity and flexibility for content protection system of digital interface.At present,the most widely used content protection schemes of digital interface are foreign specifications HDCP and DTCP.They have some deficiencies in system structure and flexibility.So designing a content protection system for digital interface that has independent intellectual property rights of our country with more functionality and flexibility is still of great significance.Firstly,relevant research results of content protection system for digital interface at home and abroad are introduced.Existing specifications of content protection system for digital interface are studied and analyzed,and their features and deficiencies are pointed out.How HDCP,the most widely used transmission protection specification for digital interface,works is mainly introduced.Secondly,on the basis of referencing existing content protection technology for digital interface,a content transmission protection system for digital interface ECPS(End-to-end Content Protection System)is proposed.ECPS consists of authentication and key negotiation,location checking,authorization control of content streams and secure transmission.It can protect the transmission of digital content between interfaces and archive stream-based authorization control.The authentication protocol of ECPS uses ECDH and elliptic curve digital signature,supports multiple algorithm choices,and achieves fast authentication by saving security information without the additional overhead of pairing procedure in HDCP.Analysis and validation using AVISPA tool show that the authentication protocol can achieve mutual authentication,key secrecy and forward security.In the Location Check of ECPS,similar schemes in existing content protection system for digital interface is improved,and the location check with pre-compution function is archived in two passes by combining twice using of the timer,sequence number and pre-compution method,which is more efficient.In authorization control,due to the lack of flexibility in authorizing control schemes based on devices in existing systems,a content stream-based control method is used and a device join and quit protocol that can be used in the circumstance of the presence of the stream converters is designed.Analysis of this method shows that the authorization control can achieve dynamic stream-based quantitative control and information collection,thus achieving the goal of differentiated controlling different content streams.Finally,the main functions of the ECPS system proposed in this thesis are simulated using C++.The simulation results show that the key generation,certification and authentication modules can run correctly.On this basis,the working process of ECPS system is further simulated.The result shows that the compliant receiver can pass the authentication procedure and smoothly play video data,while the non-compliant receiver can not play video data.