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Federated digital rights management scheme including trusted systems

  • US 8,656,183 B2
  • Filed: 06/05/2012
  • Issued: 02/18/2014
  • Est. Priority Date: 03/14/2006
  • Status: Active Grant
First Claim
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1. A method of decoding encrypted content using a playback device on which an active user encryption key is stored, where the content includes frames of video and at least a portion of a plurality of frames of video are encrypted using at least one frame encryption key, and the at least one frame encryption key is encrypted using a content encryption key, and copies of the content encryption key are separately encrypted using a plurality of different user encryption keys including the active user encryption key, the method comprising:

  • obtaining encrypted content using a playback device, where the content includes frames of video and at least a portion of a plurality of frames of video are encrypted using at least one frame encryption key;

    obtaining using the playback device a copy of the at least one frame encryption key that is encrypted using a content encryption key and copies of the content encryption key that are separately encrypted using a plurality of different user encryption keys including an active user encryption key stored on the playback device;

    determining using the playback device which of the encrypted copies of the content encryption key was encrypted using the active user encryption key stored on the playback device;

    decrypting the identified copy of the content encryption key using the playback device and the active user encryption key;

    decrypting the at least one frame encryption key using the playback device and the decrypted content encryption key;

    playing back frames of the encrypted content using the playback device, where playing back frames of the encrypted content further comprises;

    identifying any portions of a frame that are encrypted;

    identifying the frame encryption key used to encrypt the identified portions of the frame;

    decrypting the encrypted portions of the frame using the identified frame encryption key; and

    decoding the unencrypted frame of video.

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