Patent ID: 7693280

Claim:
A method for sharing a sequence of content keys between a receiver of pieces of digital content and a computing device upon which the digital content is to be rendered, the receiver encrypting each piece of content according to a corresponding content key in the sequence and forwarding the encrypted content to the computing device and the computing device decrypting the encrypted content according to the corresponding content key, the method comprising: the receiver initially transmitting to the computing device an initialization digital license including an initial content key (CK 0 ) and an initial integrity key (IK 0 ) as decided upon by the receiver and as encrypted according to a public key (PU-C) to result in an initial signed decrypted public key (PU-C(CK 0 , IK 0 )) that is decryptable by the computing device, the initialization digital license further including a signature element based on the initial integrity key (IK 0 ); the computing device receiving the initialization digital license, retrieving said decrypted public key (PU-C(CK 0 , IK 0 )) therefrom, applying a private key (PR-C) thereto corresponding to said public key (PU-C) to result in (CK 0 ) and (IK 0 ), and employing said initial integrity key (IK 0 ) to verify the signature element of such initialization license; and each of the receiver and the computing device deriving a new content key (CKx) in the sequence from the initial content key (CK 0 ) in the sequence on an as-needed basis and in a coordinated fashion, whereby the initialization license is required only once for the sequence of content keys, and the receiver need not explicitly communicate said new content key (CKx) to the computing device for each piece of content.