Digital assets are in a secured form that only those with granted access
rights can access. Even with the proper access privilege, when a secured
file is classified, at least a security clearance key is needed to ensure
those who have the right security clearance can ultimately access the
contents in the classified secured file. According to one embodiment, a
secured file or secured document includes two parts: a header, and an
encrypted data portion. The header includes security information that
points to or includes access rules, a protection key and a file key. The
access rules facilitate restrictive access to the encrypted data portion
and essentially determine who the secured document can be accessed. The
file key is used to encrypt/decrypt the encrypted data portion and
protected by the protection key. If the contents in the secured file are
classified, the file key is jointly protected by the protection key as
well as a security clearance key associated with a user attempting to
access the secured file.