DRM Basics
[The feature associated with this page, Windows Media Format 11 SDK, is a legacy feature. It has been superseded by Source Reader and Sink Writer. Source Reader and Sink Writer have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use Source Reader and Sink Writer instead of Windows Media Format 11 SDK, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]
The Windows Media DRM technologies are fairly simple from the perspective of the Windows Media Format SDK. Components of the SDK can be used to protect content and to play protected content.
Protecting Content
Protecting content (also called packaging content) involves encrypting the data section of the file and including some information in the file header that enables players to decrypt the content.
To encrypt the content, you need a key, which is a value used to seed the encryption algorithms. A key is made up of two pieces: a key seed (or private key), and a key identifier (or public key). The key seed is the secret value with which you encode content. The key identifier is a public value that is included in the header of a protected file.
When a file is protected, it cannot be decrypted without a license. A license includes information that specifies the terms of use for the protected content. The terms of a license are decided by the content owner and can be customized to meet a variety of needs. Part of the process of packaging a file is to include the URL of a Web page where users can acquire a license to access the content.
Reading Protected Content
To read protected content, a license for the content must reside on the client computer. Some license restrictions are checked internally by the DRM components of the Windows Media Format SDK, while others must be enforced by your application.
You can use the objects of the Windows Media Format SDK to assist the user in acquiring licenses for content and to perform other administrative tasks, such as updating DRM components and backing up licenses.
Note
DRM is not supported by the x64-based version of this SDK.
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