A packager packages digital content for a user and a licensor issues a
digital license to the user for the content such that the user renders
the content only in accordance with the license. The licensor and
packager share a Secret to allow the packager and the licensor to
calculate a content key (KD) for the content. To package the content for
the user, the packager calculates a content key (KD) based on the shared
Secret and a content ID and encrypts the content according to (KD). To
issue a license to the user for the content, the licensor also calculates
(KD) based on the shared Secret and the content ID, encrypts (KD)
according to a public key of the user to form the license, and sends the
license to the user.