Digital Rights Management (DRM: DIGIGSILSIT Management) is a new technology that has developed with wide dissemination of electronic audio video programs on the Internet. The working principle of DRM technology is to establish a digital program authorization center, encode the compressed digital program content, and then encrypt the content with the key, the encrypted digital program head stores the KeyID and program authorization center. Unified Resource Locator (URL) address. When the user is on demand, the related key decryption is sent after the authentication authorization of the digital program authorization center according to the KEYID and URL information of the program header, and the program is playable. The programs that need to be protected are encrypted, even if they are downloaded and spread to others by the user, the authentication authorization of the Digital Program Authorization cannot be played, so that the copyright of the program is strictly protected.
With the rapid development of mobile data value-added services, the mobile business value chain has a huge change, and the content provider is an independent ring in the value chain, its status and role have been widely recognized. The content provider must be guaranteed by the content and application software, games, etc. of information services such as business and MMS, etc., and their copyright and related benefits must be guaranteed. Therefore, in an early mobile value-added business environment, some content providers are often strictly prohibited to forward the downloaded content and applications to others.
However, the recent large number of mobile business research shows that "contagability" is a key factor in which the mobile business is popular. That is, a user's favorite content or application must be spread to its friends, colleagues, classmates, family members, etc., thereby forming the popularity of the business. It is prohibited from forwarding the "contagious" of the business to a significant reduction, and the large-scale promotion of the business has had a big contradiction. The introduction of DRM technology into mobile value-added services can be propagated in mobile networks, but also strictly guarantee the interests of content providers, so this technology has become one of the hotspots of mobile business in the world.
1. Potential demand in DRM technology in China Mobile business
With the huge success of the SMS business, China Mobile data value-added business is booming. During the SMS business, professionals and content providers specializing in SMS content creation have emerged, but once these providers are sent, they will freely propagate in the network. Since the added value of the SMS text content is low, although the random transmission of this content will cause loss of content providers, this has become a reality that the provider must face.
With the development of MMS business represented by China Mobile MMS, China Unicom "Color E", and Java Download, Mobile Games and other business have been launched, the content of mobile users can get is not only simple text information, more Ring, screensome, animation, and even high value-added digital products such as mobile games, MP3, video programs. Therefore, an increasingly urgent problem is in front of the carrier and content provider, that is how to download the user's downloads and download users to control the use and communication of the media to protect operators and content providers. Interests.
DRM technology provides a valid control method for the development of mobile data value-added services, mainly in the following four aspects.
· Allows the content provider to define the rules (copyright) used by the media object, and mobile users must be consumed by these rules.
· You can define different copyrights for a media object and develop different prices. If different copyrights are defined according to different number of use, time and play, display, operation, etc. are defined for user selection, providing a range of new business models, such as renting games, by using the number of times Playback of video programs and so on.
· Through the control of copyright, the true value of the content is reflected in the copyright, not the media object itself. In this case, the content can be forwarded and propagated according to the user's preference within the mobile network, thereby forming a traffic, but the use of the content must reapply the new copyright, which guarantees "contagious" of the business. Guaranteed the interests of the content provider.
· Through the control of copyright, DRM makes the digital copyright of the media object a source of billing. Therefore, different services can generate digital copyrights using the same DRM authorization center, and simultaneously generate billing original bill recording (CDR), simplifying the billing system, blocking the billing vulnerability, ensuring business revenue.
But a complete set of DRM technology requires a very secure channel between content providers and mobile terminals, which will cause an increase in business opening complexity and construction costs. Therefore, the application of mobile value-added business DRM should provide some safety, support some basic functions of the DRM, to support some of the basic functions of the mobile data value-added business field, to support some of the basic functions of DRM, Business development needs. At the same time, there should be a variety of DRM implementations, which provide a variety of options for business development.
Second, DRM implementation
The mobile value-added business should provide a DRM implementation of a different business. At present, a large number of research work is carried out in the implementation of DRM in mobile business. Among them, the DRM standard developed by OMA: Open Mobile Alliance has been widely supported and recognized.
In the implementation of the DRM, according to the copyright object and the download content of the copyright object and the package, it can be divided into forward-lock, combined, combined transmitry, and SPEARATE DELIVERY. Symnas, as shown in Figure 1.
here, combined transmission mode simultaneously sends a media object and a copyright object, and mobile terminals use the downloaded content according to the privilege specified by the copyright object. Since this method does not require encryption of content, it is strictly prohibited from forwarding, but it is relatively simple to achieve. The forwarding prohibition method is actually a simplified version of the combination transmission mode. In this case, there is no separate copyright object to transmit with the DRM packet, and the use of a series of default permissions on the mobile terminal controls the use of media objects. In general, the default user can use the media content anymore, but strictly prohibit forwarding. Since forwarding prohibition and combined transmission methods are essentially consistent, it can be easily compatible on the client. However, in the specific business, what kind of way is also determined by the content provider server side.
Different from the above two ways, sending methods must be encapsulated to provide higher security. The encrypted content must be opened by simultaneously generated key, unless you have a content key (CEK: Content Encryption Key), or anyone is not available. During the implementation, the encrypted content is downloaded in a normal way (which can be used in the same way as the combined transmission method, and the copyright object (including key) is passed through a safer transport channel (such as PUSH short. Message) Send to the mobile terminal. Since the content is encrypted, the end user is allowed to be forwarded in any way, ensuring copyright control and billing for forwarding content through a super-distribution mechanism. When using a separate transmission method, since the server side needs to encrypt the content, the user mobile terminal needs to decrypt the content using the key, thereby increasing the complexity of the system. At the same time, according to the current system design, the copyright object must be sent after confirmation of the encrypted content has been successfully received by the mobile terminal. Since the encrypted content and copyright objects are sent through different ways, the copyright object reaches the time of the mobile terminal. According to foreign simulation environments, this delay may reach more than 10s, which will reduce business providing speed and customer satisfaction. In order to reduce the impact of this problem, DRM must consider certain coordination mechanisms during the implementation process, such as setting parameters in the DRM content data clamp, describing the copyright message separately sent by another approximately after approximately last time.
3. The implementation of content forwarding copyright control
In the process of moving data value-added services, how to maintain "contagious" in the business, but also achieve strict control of forwarding and dissemination, is a key issue that DRM technology needs to be resolved.
currently widely accepted the use of super distribution mechanisms to strictly guarantee copyright, using the flexibility provided separately, support the needs of users in commercial models and the demand of users in business models. The typical structure of the super distribution is shown in Figure 2.
Adopt the super distribution mechanism, the content of the forwarded must be encrypted content available separately, the media object passed must be an encrypted DRM content format (DCF). Under this mechanism, the media object allows the transmission terminal to another by any way, such as MMS or local data connection), and integrates address information of the authorization center application server by means of metadata parameters. A new user who receives DRM propagation content If you want to use content, you must open an HTTP browsing link to contact the Authorization Center and select the copyright authority you need. Based on the selected copyright authority, the authorization center generates a new copyright object, still uses secure PUSH short messages to new users, and generates billing original bill records.
Another problem with super distribution is how new mobile terminal users determine whether the other party likes to forward, and can be used normally. In the normal content download process, the downloaded media type, size, and name, manufacturer, etc. are generally described by downloading the description file (Download Descriptor), and the user decides whether to like this, and the mobile terminal automatically or manually participates in judgment. Whether the machine supports the media type of the content, whether the memory capacity is sufficient. In the super distribution, there is no download process for the description file. Therefore, the feasible way can only be attached to the necessary header parameters in the packet of encrypted content, providing information similar to the download description file, the most critical is The type of the media and the length of the content. In this case, the forwarded mobile terminal can use the encrypted content header parameter to determine if the forwarding content is appropriate. If there is no problem, look at whether to send a new copyright application using the URL address of the DCF to the authorization center. If the mobile terminal cannot determine if the content is appropriate, a warning should be made to the user.
Four, junction
With the rapid development of China's mobile data value-added business, from guaranteeing operators / content providers, providing new business models, business promotion, income protection, etc. will result in the growing application needs of DRM technology. Thus, it is gradually applied. Depending on the actual needs of the business, it is possible to implement copyright control and charging of forwarding content on the basis of simple to complex, selection forward prohibition, combination transmission, respective transmission, respective, and on the basis of content encryption.
