| 摘要 |
Some embodiments of the invention provide a content-distribution system for distributing content under a variety of different basis. For instance, in some embodiments, the content-distribution system distributes device-restricted content and device-unrestricted content. Device-restricted content is content that can only be played on devices that the system associates with the particular user. Device-unrestricted content is content that can be played on any device without any restrictions. However, for at least one operation or service other than playback, device-unrestricted content has to be authenticated before this operation or service can be performed on the content. In some embodiments, the system facilitates this authentication by specifying a verification parameter for a piece of device-unrestricted content. The content-distribution system of some embodiments has a set of servers that supply (1) media storage structures that store content, (2) cryptographic keys that are needed to decrypt device-restricted content, and (3) verification parameters that are needed to verify device-unrestricted content. In some embodiments, the device that receives the media storage structure inserts the received cryptographic key or verification parameter in the received media storage structure. In some embodiments, the set of servers also supply cryptographic content keys for the device-unrestricted content. These keys are used to decrypt the content upon arrival, upon first playback, or at some other time. However, some embodiments do not store these cryptographic keys in the media storage structures for the device-unrestricted content. |
