Systems and Methods for Playing Back Alternative Streams of Protected Content Protected Using Common Cryptographic Information

A playback device, comprising:

• a processor;
• memory containing a client application;
• wherein the client application configures the processor to:
• register with a content distribution system in order to obtain cryptographic data bound to the playback device from the content distribution system;
• request adaptive bitrate streaming of protected video from the content distribution system using the bound cryptographic data;
• obtain a top level index file from the content distribution server, wherein the top level index file identifies a plurality of alternative streams of protected video that have been protected by a common set of frame keys generated by a source encoder, and wherein the top level index file comprises (i) an encrypted copy of a first key from the common set of frame keys and (ii) a set of DRM information that identifies protected portions of the alternative streams of protected video and frame keys to utilize in accessing the protected portions of the alternative streams;
• obtain a first portion of protected video from a given stream of protected video from the content distribution system, wherein the first portion of protected video is protected by the first key from the common set of frame keys;
• decrypt the encrypted copy of the first key using the bound cryptographic data;
• decrypt the first portion of protected video using the decrypted first key according to the obtained set of DRM information;
• playback the decrypted first portion of video from the given stream;
• obtain a second portion of protected video from the given stream of protected video from the content distribution system, wherein the second portion of protected video is protected by a second key from the common set of frame keys;
• obtain an encrypted copy of the second key from the common set of frame keys from the source encoder, wherein the encrypted copy of the second key has been generated by the source encoder;
• decrypt the encrypted copy of the second key using the bound cryptographic data;
• decrypt the second portion of protected video using the decrypted second key according to the obtained set of DRM information;
• and
• playback the decrypted second portion of video from the given stream.