Patent ID: 7561696

Claim:
A computer-implemented method comprising: building a root license that contains an encrypted initial content key that is asymmetrically encrypted using a public key of an intended receiver, the root license pertaining to content in an audio and/or video content file that is to be streamed to the intended receiver and the public key of a larger bit size than the root license initial content key; responsive to receipt of a license request from the intended receiver, sending the root license to the intended receiver; preparing one or more leaf licenses that are chained to the root license, the one or more leaf licenses pertaining to updated policies associated with the streamed content in the content file, wherein the one or more leaf licenses individually contain a different content key that is symmetrically encrypted using the initial content key; and responsive to receipt of a content request from the intended receiver or during streaming of protected content from the content file, sending the one or more leaf licenses to the intended receiver wherein the act of sending the one or more leaf licenses comprises interleaving portions of protected content with data that includes the one or more leaf licenses to thereby allow the intended receiver to consume the protected content in the content file by firstly asymmetrically decrypting the initial content key and successively symmetrically decrypting each content key of the one or more leaf licenses wherein a transmitter performs the sending of the one or more leaf licenses and sends each one of the one or more leaf licenses prior to sending a corresponding portion of protected content from the content file and wherein the intended receiver lacks knowledge of a number of leaf licenses to be sent by the transmitter.