DRM technology and playing Process

Windows Media Rights Manager overview idleawei@hotmail.com Windows Media Rights Manager (DRM, Microsoft Windows Media Digital Rights Management) is part of Microsoft's Windows Media Technologies. DRM is a technology used to encrypt and protect digital media files for publishing and sales. It is applied to the Internet. DRM helps owners of digital media files create a business model with high security, wide application scope, excellent compatibility, and strong scalability in the digital media field. 1. DRM workflow the owners of digital media files use the DRM platform to encrypt and publish their digital media files. When a user obtains and plays a DRM-encrypted file through a web server or Streaming Media Server (Streaming Media Server, such as a Windows Media Server) or other means, A player that supports DRM first sends a playback permission request to a specified Certificate Server (License Server). After a set process, the player obtains the playback certificate of the file, finally, play the media file. This section describes how a digital media file is encrypted and released by DRM: [img] http://www.microsoft.com/windows/windowsmedia/images/drm/flowchart.gif#/img] the workflow of DRM is analyzed based on the chart. 1. encrypted digital media files can be files containing songs, images, or other digital media content. The file owner (content owner) uses Windows Media right manager to encrypt the file. Encrypted Files are like locked by a specific lock. To play a file, you must use a dedicated key to open the lock. The key is stored in an encrypted certificate. The certificate is released independently of a media file. When you encrypt a media file, some additional information will be added to the file, such as the address (URL) published by the certificate ). Encrypted files will be stored in the Microsoft audio file format (WMA format) or Microsoft Video Format (WMV Format. 2. encrypted media files can be published through websites, streaming technology, streaming media servers, and CD or email. Windows Media Rights Manager allows consumers to pass copyrighted media files to their friends.

3. The content owner of the Certificate Server needs to select a place to store the certificate and plan the publishing of the certificate to complete the certificate publishing service function of DRM. The Microsoft Certificate Server can perform this task. The Certificate Server is used to review the consumer's playback application. The independent storage and publishing of media files and playback certificates facilitate the management and operation of the entire DRM system. 4. Obtain media files 5. Apply for a playback certificate 6. The consumer can obtain or play media files through the web site and streaming media server. When a consumer uses a player that supports DRM to play encrypted files for the first time, the player automatically requests a playback certificate from the specified Certificate Server. The specific key contained in this certificate will be used to open the lock on the file. You can customize the certificate playback process to let consumers know the certificate publishing process. For example, you can ask the consumer to fill out some necessary application forms, or you may not let the consumer know, secretly publishing the certificate. 7. To play encrypted digital files, you must use a media player that supports DRM. The consumer can play a file within a certain period of time, or play it for a certain number of times (for example, only four files can be played ). The content owner can set these restrictions when encrypting files, and can also set whether to allow mobile devices to play encrypted files. The consumer transfers files between friends, but when a friend needs to play files, he also needs to apply for a playback certificate from the Certificate Server, because the playback certificate is designed to be inaccessible. This will ensure the interests of the content owner. The above is a brief introduction to the DRM workflow. The following describes some features about the certificate and key settlement. II. A brief description of the certificate and key features (license and keys). The content owner uses a "Lock" to encrypt files. Before the consumer can play encrypted files, the key used to open the lock will be stored in the playback certificate and sent to the consumer. The following figure shows how Windows Media Rights Manager generates keys. [Img] to generate a key, you first need the license key seed and key ID: ■ The Key seed value is only the content owner and the certificate issuer (Certificate Server) yes.

■ The key ID is used to mark each media file. Its values are stored in encrypted media files. When the Certificate Server receives a certificate request, the server will obtain the key ID in the encrypted file and the license key seed stored on the server to re-generate the key, this key is stored in the certificate and then sent to the requester. Then the requester can use the certificate to open and play the encrypted file. A Brief Introduction to the certificate each certificate contains a key used to open the decryption file. The certificate also contains other information used to manage the playback of media files. Content owners can use the default restricted playback attributes to set more restricted playback attributes. Windows Media Rights Manager certificates can provide a wide range of business specifications, including the following: ■ set the number of times a file is allowed to be played ■ set the device that can be used to play or spread files. For example, you can set the file to be transmitted to a mobile device that supports sdmi (Secure Digital Music Initiative). ■ set the time when the file can be played and the expiration time when the file cannot be played. ■ Set whether the file can be burned to the CD. ■ The certificate can be backed up or stored by the user. ■ Sets the security level used to play the file system. Certificates can be transferred in different ways and at different times, depending on the business model. The content owner may want to pre-publish the certificate, or ask the consumer to request publishing after playing the file. The delivery of certificates can be known to consumers or published in unknown ways. The above documents translation, adapted Microsoft Site related documents: http://www.microsoft.com/windows/windowsmedia/defau