A method is disclosed for a device to interdependently validate a digital
content package having a piece of digital content in an encrypted form,
and a corresponding digital license for rendering the digital content. A
first key is derived from a source available to the device, and a first
digital signature is obtained from the digital content package. The first
key is applied to the first digital signature to validate the first
digital signature and the digital content package. A second key is
derived based on the first digital signature, and a second digital
signature is obtained from the license. The second key is applied to the
second digital signature to validate the second digital signature and the
license.