The generic DRM architecture accepted to all includes three core components: the content packaging server, the license server and the client [2], [3].. Content repository Product datab
Trang 1The main driving force of DRM comes from industry [1] The most representative sample is the protection of eBook, electronic music, and digital movie Several fa-mous international companies have release their own solutions and productions, such
as Microsoft’s WMRM, Real Networks’ Helix DRM, Adobe’s Content Server, and IBM’s EMMS
2 Current DRM Systems
2.1 Classification of DRM Systems
Existing DRM systems could be classified into different categories according to dif-ferent standards (such as safety technique chosen, protected object, etc.) The pro-tected objects include: software, eBook, images, stream media and contents on mobile devices
The main function of software-protected DRM system is the precaution of software piracy The protection of software appeared in the 1980s, which could be regarded as the earliest application of DRM In the early times, the methods to prevent software piracy include the usage of key floppy disk, copy-proofed CD, encryption card, etc Many new software-protection forms appear along with the development of DRM technology and network technology
The eBook-protected DRM systems have two kinds of applications: the online bookstore (such as Amazon, eReader), and the digital library (such as netLibrary, Apabi) The online bookstore sells eBook directly to the readers while the digital library only provides borrowing service, and both of them have to protect the rights against infringement by third parties
The images-protected DRM systems are somewhat complex Some websites attach their own logo onto the images to prevent others from using it illegally But the visi-ble logo sacrificed the image’s quality Another preferavisi-ble method is to embed the copyright information into the images by digital watermarking If someone used the images without authorization, the owner could detect the copyright information hided
in the images with special software, and prove it Now the companies who focus on digital watermarking include: Digimarc in USA and High Water Signum in England They provide similar service In China the “Patriot Banshen” digital watermarking system could satisfy the requirement [8] Digital watermarking could also be used in stream media market
The stream media-protected DRM system protects electronic music, electronic movies and videos Now some marketers have used DRM technology Some famous stream media systems have their own rights management solutions, such as WMRM, EMMS and Helix DRM, etc
The DRM system used on movable device can protect images, ringtone, mp3, mp4, etc Because the movable platform is different from PC platform, the embedded sys-tems present new technological demands on DRM At present, some mobile phone (such as Nokia) has applied DRM technology supporting OMA DRM [15] Along with the development of intelligent mobile phone, the DRM still cannot achieve real copyrights protection
Trang 22.2 Decisive Concepts in DRM
The research on DRM always includes the architecture, content security, rights expres-sion, as well as authentication The systems are different in those points This section is mainly about their characteristics, and gives a contrast on current DRM systems
Architecture. The generic DRM architecture accepted to all includes three core components: the content packaging server, the license server and the client [2], [3]
Content
repository
Product
database
DRM packager
Content Packaging
Server
Rights
database
Encryption
key database
License Server
Identify attribute database
DRM license generator
Client
content
metadata encryption
keys
rights encryption
DRM controller Content package
License package
Identifying attributes
Financial transaction
Rendering application
Fig 1 The generic DRM architecture
The DRM packager in content packaging server encrypts the content and transfers them to the user through P2P, email, or downloading service, etc the rights package will be transferred to license server
The DRM controller in client determines the way the user using the content, through policies bound to the package and implicit in the packaging format, that the requested use requires authorization If the license cannot be found on the user’s ma-chine or has expired The DRM controller should make rights request by packaging and sending attributes of the user and the content to a license server
The license server verifies the submitted client identification or attributes creden-tials, creates license, packaged and transferred to client securely
For more information about DRM architecture, you may access [2], [3], [4]
Trang 3Content Security.Generally, the protection of digital content is based on encryption
technology, namely encrypting the digital content at first before distribution So the
unauthorized user cannot get valuable information even they have intercepted the
content during transmission successfully Digital watermarking is a new direction in
information security field It can protect the copyright and integrity of information
Digital watermarking is applied in those fields: remote monitor and control, owner
authentication, ownership verification, operation tracking, content identification, copy
restriction and device control
Rights Expression. Rights Expression plays an important role in DRM, it works by
rights expression language (REL) Existing works in this area include the INDECS
project One of the basic distributions of this project is clearly separating and
identifying the three core entities: Users, Content, and Rights [3] Users can be any
type: from a rights holder to an end consumer Content also can be any type of content
at any level of aggregation The rights entity is an expression of the permissions,
constraints, and obligations between the Users and the Content Most of the existing
RELs are XML-based The two most developed RELs are XrML [14] and ODRL
[12], [13]
Authentication Authentication is a fundamental part of any DRM system, because it
is the foundation of rights management The DRM system verifies the reality and
validity of the user’s identity, then determines whether make authorization or not with
the results The most applied authentication technologies are password-confirming
and hardware binding
Table 1 A Contrast among the systems Concepts
protected
Objects
Architecture Content Security Rights
Description
Authentication Software C/S
Structure
Encryption, Digital Watermarking
Software ID eBook Typical
Structure
Encryption, Digital Watermarking
EBX User/Password Stream Media Typical
Structure
Encryption, Digital Watermarking
XrML/
MPEG REL
User/Password Hardware ID Mobile Typical
Structure
Hardware ID
A Contrast among Systems Actually, the DRM systems have both same and special
characteristics in the four aspects mentioned above As shown in Table 1
The digital rights management of images is somewhat complex, and the relevant
technologies are not mature enough Most of the researches are limited to the
declara-tion of the rights ownership and the tracking of rights by digital watermarking It is
always used after the act of tort has happen We will not make a conclusion in this
paper
Trang 43 Digital Rights Management in Education
Digital rights management is complex and difficult regardless of the application do-main Nonetheless, education places some very specific demands on it This section introduces the specific requirement presented by education for DRM, discusses the security technology available, and analyzes their merits and demerits
3.1 Specific Requirements Presented by Education
IEEE LTSC DREL Study Group makes a deeply study on the domain features of education, learning, and training [4] The prominent ones of them are listed below:
• In the education area, the education resources may have multiple authors for the joint authorship is very common The educational resources may be reconstructed from multiple learning objects The rights expression language of the DRM system must be able to identify rights information associated with component learning ob-jects and with contributing authors as distinct from rights associated with aggregate works
• In web-based education, the users participate in learning, reuse the educational resources, and all of these will raise the privacy problem, for the privacy may be protected by privacy acts and local policies The DRM system has to consider these acts and policies carefully
• Learning, education and training are all highly local activities, yet the education resources will be created and distributed across jurisdictional and domain bounda-ries in a distributed education So the rights should be expressed from a combina-tion of local and global context
• Actually, Profits is always not the main objective of creating the intellectual prop-erty in education, and the attribution seems more important Most of the authors are wish to share their ideas if they are in fact properly acknowledged with some con-straints, even the constraints may be different according to the practical situation
• In the copyright laws, there are always some items about “fair use” refers to educa-tion and research, as a result, maybe we cannot just divide the users simply into the authorized and the unauthorized
3.2 Security Technology Issues
Security technology issues must be considered in digital rights management applica-tion Actually these issues include authentication and content security which were mentioned above in section 2
Authentication is the foundation of rights management, and it is also a very impor-tant part of DRM system The DRM system verifies the reality and validity of the user’s identity then make decision with the results Most of the e-learning systems are made up by databases and platforms, in which different platforms provide different services The COLIS project [5] in Australia use SSO to realize the integrity of ser-vices SSO means a user signs on once in a system, he or she could access all the systems that trust the first system SSO is integrity on the “Authentication” level
Trang 5Content Security can be realized by digital watermarking or data encryption tech-nology Also there is web scripting technology can be used in DRM for educational resources for most of the resources can be formatted by HTML
Digital Watermarking Digital watermark is a pattern of bits inserted into digital
im-ages, audio or video files that identifies the file’s copyright information (author, rights, etc.), but these information are always invisible, or in the case of audio clips, inaudible Moreover, the actual bits representing the watermark must be scattered throughout the file in such a way that they cannot be identified and manipulated And finally, the digital watermark must be robust enough so that it can withstand normal changes to the file The purpose of digital watermarks is to provide copyright protec-tion for intellectual property that’s in digital format
Digital watermark is just for tracking the copyright information other than assuring the security of content It can be used in the protection of sharable educational resources
Data Encryption Data encryption is the basic security technology in the network
Encryption is the most effective way to achieve data security It is a proactive defense policy, provides huge security with very small cost There are two main types of en-cryption: asymmetric encryption (also called public-key encryption) and symmetric encryption
Encrypting digital works is foundational in copyrights protection The content pro-tection in DRM is mainly based on encryption To read the encrypted file, you must have access to a secret key or password that enables you to decrypt it Most of the existing stream media DRM systems are based on data encryption technology Al-though very safe, these systems go against retrieval, go against the sharing and com-munication of educational resources
Web Scripting Technology The web scripting technology controls access to the web
page’s content by inserting functional scripting code into the source code Such as disabling right click, disabling select, disabling edit, disabling printing, and so on It also could restrict the time of access and operation This method can protect educa-tional resources on certain level, but this low security is only satisfied the demands of some valueless resources
Data encryption and digital watermarking both have their own merits and demerits,
as shown in Table 2
Table 2 Comparison of data encryption and digital watermarking
Data Encryption Digital Watermarking
Control the access to the content Detect and track the hiding content
Content-irrelevant Content-relevant
The terminal has to demonstrate
the decryption process
The terminal has not to demonstrate the decryption process
Attacking techniques is mainly
signal processing,
which will make the content
hides invaliable
Attacking techniques is mainly decryption
Has intensity of D/M and M/D Has no intensity of D/M and M/D
System security has nothing to
do with the terminal device
System security is determined by security of terminal device