Abstract: A request to render encrypted content is received and a chain of licenses corresponding to the content is located. The chain includes a leaf license linked to the content at one end of the chain, a root license at the other end of the chain, and any intermediate licenses therebetween. The leaf license and any intermediate licenses in the chain are each bound to the adjoining license in the chain toward the root license, and the root license is bound to an owner of a private key (PR-U). For each license in the chain, the license is verified and it is confirmed that the license allows the content to be rendered. A decryption key is obtained from the leaf license based on application of (PR-U) to the root license, the obtained key is applied to decrypt the encrypted content, and the decrypted content is rendered.

Abstract: A digital license includes an identification of a removal service that can authorize removing such license. A client selects the license to be removed and the service, constructs a challenge including therein a challenge license identification block (LIB) identifying the license to be removed, and sends the challenge to the service. The service receives the challenge, stores at least a portion of the challenge in a database, constructs a response corresponding to the challenge and including therein a response LIB identifying the license to be removed and an identification of the service, and sends the response to the client. The client receives the response, employs the response LIB from the response to identify the license to be removed, and removes the identified license upon confirming that the identification of the service in the identified license matches the identification of the service in the response.

Abstract: A source generates a medium key (KM) and a media secret table including a plurality of entries, each entry including (KM) encrypted by a public key (PU-PD) of a plurality of devices, obtains the medium ID of a medium therefrom, generates a content key (KD) for a piece of content, encrypts the content with (KD) to result in (KD(content)), encrypts (KD) with (KM) to result in (KM(KD)), generates a package for the content including (KD(content)), (KM(KD)), the medium ID, and a signature based on at least the medium ID and verifiable with (KM), and copies the generated package and the media secret table to the medium. Thus, a device with the medium and a private key (PR-PD) corresponding to an entry of the media secret table can access and render the content.