# US 8,909,922 B2 · Systems and methods for playing back alternative streams of protected content protected using common cryptographic information

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- Number: US 8,909,922 B2
- Document ID: US8909922B2
- Status: Granted
- Kind: B2
- Application number: 13/340,623
- Filed: 2011-12-29
- Published: 2013-03-07
- Granted: 2014-12-09
- Earliest claimed: 2011-09-01
- Assignees: Sonic IP, Inc.
- Applicants: Michael George Kiefer; Eric William Grab; Jason Braness
- Inventors: Michael George Kiefer; Eric William Grab; Jason Braness
- Web page: https://patentgrep.com/patent/US8909922B2

## CPC

- H04N 21/2347: involving video stream encryption
- H04L 9/0819: {Key transport or distribution, i.e. key establishment techniques where one party creates or otherwise obtains a secret value, and securely transfers it to the other(s) (network architectures or network communication protocols for key distribution in a packet data network H04L63/062)}
- H04L 9/0822: {using key encryption key}
- H04L 9/0861: {Generation of secret information including derivation or calculation of cryptographic keys or passwords}
- H04L 9/14: using a plurality of keys or algorithms
- H04L 9/32: including means for verifying the identity or authority of a user of the system {or for message authentication, e.g. authorization, entity authentication, data integrity or data verification, non-repudiation, key authentication or verification of credentials}
- H04L 63/0428: {wherein the data content is protected, e.g. by encrypting or encapsulating the payload}
- H04N 21/2541: {Rights Management (protecting software against unauthorised usage in a vending or licensing environment G06F21/10; security in data switching network management H04L41/28; security management or policies for network security H04L63/20; access security in wireless networks H04W12/08)}
- H04N 21/4408: involving video stream encryption, e.g. re-encrypting a decrypted video stream for redistribution in a home network
- H04N 21/4627: Rights management {associated to the content (security in data switching network management H04L41/28; security management or policies for network security H04L63/20; access security in wireless networks H04W12/08)}
- H04N 21/6334: for authorisation, e.g. by transmitting a key {(wireless communications network key management H04W12/04; wireless communications network access security H04W12/08)}
- H04N 21/64715: {Protecting content from unauthorized alteration within the network (verifying the information received for network security in communication control or processing H04L63/12; integrity in wireless network security H04W12/10)}
- H04L 2209/603: Digital right managament [DRM]
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

Systems and methods for performing adaptive bitrate streaming using alternative streams of protected content in accordance with embodiments of the invention are described. One embodiment of the invention includes a processor, and memory containing a client application. In addition, the client application configures the processor to: request a top level index file identifying a plurality of alternative streams of protected content, where each of the alternative streams of protected content are encrypted using common cryptographic information; obtain the common cryptographic information; request portions of content from at least the plurality of alternative streams of protected content; access the protected content using the common cryptographic information; and playback the content.

## Claims

### Claim 1

A playback device, comprising:
a processor;
memory containing a client application;
wherein the client application configures the processor to:
obtain a top level index file identifying a plurality of separate container files each containing one of a plurality of alternative streams of protected video, wherein each of the alternative streams of protected video includes video frames that are encrypted using a common set of frame keys comprising a plurality of different frame keys, wherein each of the container files containing the alternative streams of protected video comprises (i) an encrypted copy of the common set of frame keys and (ii) a set of DRM information that identifies encrypted portions of the video frames and frame keys to utilize in accessing the encrypted portions of the video frames, and wherein the set of DRM information in each of the plurality of alternative streams of protected video references the same common set of frame keys;
obtain an encrypted copy of the common set of frame keys from a given container file and decrypt the encrypted copy of the common set of frame keys using a content key;
obtain a set of DRM information from the given container file;
obtain portions of protected video from the given container file containing one of the plurality of alternative streams of protected video;
decrypt encrypted video frames from the obtained portions of video using the decrypted copy of the common set of frame keys according to the obtained set of DRM information; and
playback the obtained portions of video.

### Claim 2 (depends on 1)

The playback device of claim 1, wherein:
the alternative streams of protected video are encoded at different maximum bitrates using different sets of encoding parameters; and
the client application further configures the processor to
decode the encoded frames of video prior to playback of the obtained portions of video.

### Claim 3 (depends on 1)

The playback device of claim 1, wherein:
the container files containing each of the alternative streams of protected video comprise at least one header that includes information that describes the encoding of the stream of protected video; and
the top level index file identifies the location of the at least one header within each container file.

### Claim 4 (depends on 1)

The playback device of claim 1, wherein the common set of frame keys is part of a frame key table that is common to each of the plurality of alternative streams.

### Claim 5 (depends on 1)

The playback device of claim 1, wherein:
the client application further configures the processor to securely receive the content key.

### Claim 6 (depends on 1)

The playback device of claim 1, wherein:
each container file containing one of the alternative streams of protected video further comprises an index; and
the client application further configures the processor to:
request at least a portion of an index from the given container file;
identify the portion of the given container file containing a specific portion of video using the index; and
request the identified portion of the given container file.

### Claim 7 (depends on 1)

The playback device of claim 1, wherein the container files are Matroska container files.

### Claim 8 (depends on 7)

The playback device of claim 7, wherein the encrypted copy of the common set of frame keys is stored in a common DRM Header element contained within a Tracks element within each of the Matroska container files containing the alternative streams of protected video.

### Claim 9 (depends on 8)

The playback device of claim 8, wherein the client application further configures the processor to:
obtain the content key that can be used to decrypt the encrypted copy of the set of frame keys stored within the common DRM Header element; and
decrypt the encrypted copy of the set of frame keys stored within the common DRM Header element using the obtained content key.

### Claim 10 (depends on 8)

The playback device of claim 8, wherein the client application configures the processor to obtain the common DRM Header element by requesting a Tracks element from one of the Matroska container files identified in the top level index file.

### Claim 11 (depends on 10)

The playback device of claim 10, wherein:
each Mastroska container file containing an alternative stream of protected video further comprises an index contained within a Cues element; and
the client application further configures the processor to request a portion of video from one of the Matroska container files by configuring the processor to:
request at least a portion of a Cues element from a Matroska container file containing one of the alternative streams of protected video;
identify a portion of the Matroska container file containing a specific portion of video using at least one CueTrackPosition element within the Cues element; and
request the portion of the Matroska container file identified by the at least one CueTrackPosition element.

### Claim 12 (depends on 11)

The playback device of claim 11, wherein the index comprises a plurality of CueTrackPosition elements that identify the location of a plurality of Cluster elements within the Matroska container file.

### Claim 13 (depends on 11)

The playback device of claim 11, wherein:
each of the Matroska container files containing an alternative stream of protected video includes a set of BlockGroup elements that each contain a DRMInfo element and an encrypted frame of video, where the DRMInfo element is a part of the set of DRM information for each of the Matroska container files; and
the client application further configures the processor to decrypt encrypted video frames of the obtained portions of video using the decrypted copy of the common set of frame keys by configuring the processor to:
obtain a BlockGroup containing an encrypted frame of video;
parse the BlockGroup element to obtain a DRMInfo element indicating at least a portion of the encrypted frame of video that is encrypted using a frame key from the common set of frame keys;
decrypt the at least one encrypted portion of the encrypted frame of video using the identified frame key; and
decode the frame of video.

### Claim 14 (depends on 12)

The playback device of claim 12, wherein:
each Cluster element contains a plurality of BlockGroup elements including encoded portions of video;
a CueTrack Position element indexes each Cluster element; and
each CueTrackPosition element includes the size of the Cluster element that it indexes.

### Claim 15

A method of performing adaptive bitrate streaming using a plurality of alternative streams of protected video, the method comprising:
obtaining a top level index file identifying a plurality of separate container files each containing one of a plurality of alternative streams of protected video using a playback device, wherein each of the alternative streams of protected video include video frames that are encrypted using a common set of frame keys comprising a plurality of different frame keys, and wherein each of the container files containing the alternative streams of protected video comprises (i) an encrypted copy of the common set of frame keys and (ii) a set of DRM information that identifies encrypted portions of the video frames and frame keys to utilize in accessing the encrypted portions of the video frames, and wherein the set of DRM information in each of the plurality of alternative streams of protected video references the same common set of frame keys;
obtaining an encrypted copy of the common set of frame keys from a given container file and decrypting the encrypted copy of the common set of frame keys using a content key using the playback device;
obtaining a set of DRM information from the given container file using the playback device;
obtaining portions of video from the given container file containing one of the plurality of alternative streams of protected video using the playback device;
decrypting encrypted video frames from the obtained portions of video using the playback device and the decrypted copy of the common set of frame keys according to the obtained set of DRM information; and
playing back the obtained portions of video using the playback device.

### Claim 16 (depends on 15)

The method of claim 15, wherein:
the alternative streams of protected video are encoded at different maximum bitrates using different sets of encoding parameters; and
the method further comprises
decoding the encoded frames of video using the playback device prior to playback of the obtained portions of video.

### Claim 17 (depends on 15)

The method of claim 15, wherein:
the container files containing each of the alternative streams of protected video comprise at least one header that includes information and information that describes the encoding of the stream of protected video; and
the top level index file identifies the location of the at least one header within each container file.

### Claim 18 (depends on 17)

The method of claim 17, further comprising obtaining an encrypted copy of the common set of frame keys by requesting at least one header of a container file identified in the top level index file using the playback device.

### Claim 19 (depends on 18)

The method of claim 18, wherein:
each container file containing one of the alternative streams of protected video further comprises an index; and
the method further comprising:
requesting at least a portion of an index from the given container file using the playback device;
identify the portion of the given container file containing a specific portion of video using the playback device and the index; and
requesting the identified portion of the given container file using the playback device.

### Claim 20 (depends on 17)

The method of claim 17, wherein the container files are Matroska container files.

### Claim 21 (depends on 20)

The method of claim 20, wherein the encrypted copy of the common set of frame keys is stored in a common DRM Header element contained within a Tracks element within each of the Matroska container files containing the alternative streams of protected video.

### Claim 22 (depends on 21)

The method of claim 21, further comprising obtaining the common DRM Header element by requesting a Tracks element from one of the Matroska container files identified in the top level index file.

### Claim 23 (depends on 22)

The method of claim 22, wherein:
each Mastroska container file containing an alternative stream of protected video further comprises an index contained within a Cues element;
the method further comprises:
requesting at least a portion of a Cues element from a Matroska container file containing one of the alternative streams of protected video using the playback device;
identifying a portion of the Matroska container file containing a specific portion of video using the playback device and at least one CueTrackPosition element within the Cues element; and
requesting the portion of the Matroska container file identified by the at least one CueTrackPosition element.

### Claim 24 (depends on 23)

The method of claim 23, wherein the index comprises a plurality of CueTrackPosition elements that identify the location of a plurality of Cluster elements within the Matroska container file.

### Claim 25 (depends on 24)

The method of claim 24, wherein:
each Cluster element contains a plurality of BlockGroup elements including encoded portions of video;
a CueTrack Position element indexes each Cluster element; and
each CueTrackPosition element includes the size of the Cluster element that it indexes.

### Claim 26 (depends on 23)

The method of claim 23, wherein:
each of the Matroska container files containing an alternative stream of protected video includes a set of BlockGroup elements that each contain a DRMInfo element and an encrypted frame of video, where the DRMInfo element is a part of the set of DRM information for each of the Matroska container files; and
the method further comprising:
obtaining a BlockGroup containing an encrypted frame of video using the playback device;
parsing the BlockGroup element to obtain a DRMInfo element indicating at least a portion of the encrypted frame of video that is encrypted using the playback device and a frame key from the common set of frame keys;
decrypting the at least one encrypted portion of the encrypted frame of video using the playback device and the identified frame key; and
decoding the frame of video using the playback device.

### Claim 27 (depends on 15)

The method of claim 15, wherein the common set of frame keys is part of a frame key table that is common to each of the plurality of alternative streams.

### Claim 28 (depends on 15)

The method of claim 15, wherein:
the method further comprises securely obtaining the content key using the playback device.

### Claim 29 (depends on 15)

The method of claim 15, wherein the content key is bound to the playback device.

### Claim 30

A non-transitory machine readable medium containing processor instructions, where execution of the instructions by a processor causes the processor to perform a process comprising:
obtaining a top level index file identifying a plurality of separate container files each containing one of a plurality of alternative streams of protected video, wherein each of the alternative streams of protected video include video frames that are encrypted using a common set of frame keys comprising a plurality of different frame keys, and wherein each of the container files containing the alternative streams of protected video comprises (i) an encrypted copy of the common set of frame keys and (ii) a set of DRM information that identifies encrypted portions of the video frames and frame keys to utilize in accessing the encrypted portions of the video frames, and wherein the set of DRM information in each of the plurality of alternative streams of protected video references the same common set of frame keys;
obtaining an encrypted copy of the common set of frame keys from a given container file and decrypting the encrypted copy of the common set of frame keys using a content key;
obtaining a set of DRM information from the given container file;
obtaining portions of video from the given container file containing one of the plurality of alternative streams of protected video;
decrypting encrypted video frames from the obtained portions of video using the decrypted copy of the common set of frame keys according to the obtained set of DRM information; and
playing back the obtained portions of video.

### Claim 31 (depends on 30)

The non-transitory machine readable medium of claim 30, wherein:
the alternative streams of protected video are encoded at different maximum bitrates using different sets of encoding parameters; and
execution of the instructions by a processor also causes the processor to perform a process comprising
decoding the encoded frames of video prior to playback of the obtain portions of video.