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.