| 摘要 |
Content such as computer software, data representing audiovisual works, and electronic documents can converted from a machine-bound state to user-bound state without modification to the content data itself. Instead, keys used to access the content are converted from the machine-bound state to the user-bound state. In particular, the keys are kept in a passport data structure which can represent either a machine-binding or a user-binding. A machine-bound passport can be upgraded to a user-bound passport without modifying the bound content. The private key of the machine-bound passport, in cleartext form, is included in the user-bound passport and encrypted using a user-supplied password to bind the private key to the user. In addition, private user information is collected and verified and included in the user-bound passport. Upgrading a machine-bound passport can be initiated automatically upon detection that an attempt is made to play back machine-bound content on a machine other than the one to which the content is bound.
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