Patent ID: 7073063

Claim:
A method for a user at a second computing device to render encrypted digital content on a first computing device distinct from the second device, the first device having a public key (PU 1 ) and a corresponding private key (PR 1 ), the second device having a public key (PU 2 ) and a corresponding private key (PR 2 ), the digital content being encrypted according to a content key (KD), the method comprising: the user at the second device obtaining from a licensor distinct from the second device a digital license corresponding to the content and the second device the digital license including the content key (KD) therein encrypted according to the public key (PU 2 ) of the second device (PU 2 (KD)), and also including rules for determining whether the license permits issuance of a sub-license from the second device to the first device; the user at the second device determining that the rules of the license do in fact permit issuance of a sub-license from the second device to the first device; the user at the second device decrypting (PU 2 (KD)) from the digital license with the corresponding private key (PR 2 ) to produce the content key (KD); the user at the second device obtaining from the first device the public key thereof (PU 1 ); the user at the second device encrypting the content key (KD) according to the public key (PU 1 ) of the first device (PU 1 (KD)); and the user at the second device composing the sub-license corresponding to and based on the obtained license for the first device, the sub-license including (PU 1 (KD)), and transferring the composed sub-license to the first device, wherein the first device can decrypt (PU 1 (KD)) with the private key thereof (PR 1 ) to produce the content key (KD), and can render the encrypted content on the first device with the produced content key (KD).