A system for providing persistent access control of protected content is
disclosed. The method on a client system includes sending a first request
for authentication of the client to a server system. Subsequently, the
client is authenticated by the server. Next, a user on the client
attempts to access a file comprising a trailer and content encrypted with
an encrypting key. Then, a second request for access to the content is
sent to the server by the client, wherein an identifier from the trailer
is included in the second request. The identifier identifies the content
or an access control policy of the content. The server determines that
the second request is in accordance with an access control policy
associated with the content, and grants access to the content. Lastly,
the client accesses the content in accordance with the access control
policy.