Method and apparatus for key distribution with implicit offline authorization

摘要

In a Digital Rights Management (DRM) system, cryptographic keys for decrypting distributed assets (such as audio or video media) are distributed using an offline (e.g., non-Internet) method for distribution of the key generation process, with an implicit authorization to use the distributed key generation process. This is used to update an asset key for use by a client such as a media player when a key formula for generating the key for decrypting an asset has been compromised, such as by hackers.

主权项

1. A method, performed by a computing device, to distribute cryptographic keys, the method comprising:
storing, at a computing device, a key package including a plurality of representations of a cryptographic asset key associated with an asset, wherein each key representation has an associated key generation function to derive the cryptographic asset key; transmitting the key package to at least one client via a computer network, wherein the client is another computing device; at a time subsequent to the transmission, delivering to the client a key generation function associated with one of the key representations, accompanied by instructions to derive the cryptographic asset key from the delivered key generation function and the associated key representation in the key package, in place of the key representation and key generation function previously used by the client to derive the cryptographic asset key.