Patent ID: 9729316
Date: 2017-08-08
CPC Classifications: G09C,H04L

Claim:
1. A method for a media device to decrypt protected content on media, said content being enabled to identify device keys in a compromised media device, comprising: processing a tree-based media key block to yield an initial value, wherein the tree-based media key block that has been divided into subtrees and a media device is associated with one of said subtrees; executing a key transformation program to transform the initial value into a media key variant, the media comprising said program; in response to the executing, the media device returning to the transformation program the media device's subtree identity; deriving title keys using the media key variant; decrypting said content using the title keys; and wherein said program: executes on said device when said device attempts to decrypt said content, transforms initial values into media key variations, and identifies to a content protection licensing agency which subtree among said subtrees is associated with said device.