Unified broadcast encryption system

Patent metadata

Field	Value
Publication number	US-9729316-B2
Application number	US-3877308-A
Country	US
Kind code	B2
Filing date	Feb 27, 2008
Priority date	Feb 27, 2008
Publication date	Aug 8, 2017
Grant date	Aug 8, 2017

Abstract

A system and method is disclosed for performing unified broadcast encryption and traitor tracing for digital content. In one embodiment a media key tree is divided into S subtrees, the media key tree including media keys and initial values, which may be random values. The digital content is divided into a plurality of segments and at least some of the segments are converted into a plurality of variations. The random values are transformed into media key variations and a separate media key variant is assigned to each of the subdivided subtrees. A unified media key block including the media key tree is stored on the media.

First claim

We 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.

2. A computer program product for a media device to decrypt protected content on media, said content being enabled to identify device keys in a compromised media device, the computer program product comprising a non-transitory computer readable storage medium having computer program code embodied therewith, said program code being readable/executable by said device to:
process 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;
execute 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 returns to the transformation program the media device's subtree identity;
derive title keys using the media key variant;
decrypt said content using the title keys; and
wherein said transformation 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.

Assignees

• Jin Hongxia
• Lotspiech Jeffrey Bruce
• IBM

Inventors

• Jin Hongxia
• Lotspiech Jeffrey Bruce

Classifications

• H04L9/0836 Primary

  using tree structure or hierarchical structure · CPC title

• H04L2209/606

  Traitor tracing · CPC title

• G09C5/00

  Ciphering apparatus or methods not provided for in the preceding groups, e.g. involving the concealment or deformation of graphic data such as designs, written or printed messages · CPC title