Patent ID: 7864953

Claim:
A method for encrypting one or more content files, the method comprising: generating, by a cryptographic device having one or more computer processors and being part of a home network, a first binding key based on binding information, the binding information comprising a media key block, a binding identifier that is a common network identifier for the home network, and an authorization table indicating all receivers in the home network; encrypting by the cryptographic device a secret key using the first binding key, the secret key being associated with a group of content files associated with the home network; generating by the cryptographic device a title key for each of the content files in the group, each title key being associated with one of the content files; encrypting by the cryptographic device only the title keys for each of the content files using the secret key; encrypting by the cryptographic device each content file using the title key associated with the each content file; updating by the cryptographic device a state of each content file based on the encrypted secret key; receiving by the cryptographic device an indication that the binding information has changed from a source; generating by the cryptographic device a new binding key to replace the first binding key based on the changed binding information; recovering the secret key by using the first binding key to decrypt the encrypted secret key; re-encrypting by the cryptographic device the secret key using the new binding key without re-encrypting each title key and each content file; and updating by the cryptographic device the state of the one or more content files in response to the re-encrypted secret key without updating a state for each title key.