HDCP is already broken : http://apache.dataloss.nl/~fred/www.nunce.org/hdcp/hdcp111901.htm.
The authors conclude that "we can:
Eavesdrop on any data
Clone any device with only their public key
Avoid any blacklist on devices
Create new device keyvectors.
In aggregate, we can usurp the authority completely."
In DRM, you hand over the data, the key and the algorithm to the consumer. You can try to obfuscate, but sooner or later it will be broken. :P