Managing encryption keys for content

Disclosed are systems and methods for encryption key management. Content items, or portions thereof, can be assigned to a plurality of partitions. Each of the plurality of partitions can correspond to a timeframe of encryption key rotation. Cache control can be applied to manifests and/or content based on the timeframe of encryption key rotation.

BACKGROUND

Content transmitted to user devices may be encrypted using encryption keys. Periodically, the encryption key used to encrypt content can be changed. For example, if a given encryption key is compromised, a new encryption key may be needed to encrypt content. As another example, policies may dictate periodic changes in which encryption keys are used to encrypt content. User devices possessing decryption keys corresponding to deprecated encryption keys may experience errors. These and other shortcomings are addressed by the approaches set forth herein.

SUMMARY

It is to be understood that both the following general description and the following detailed description are exemplary and explanatory only and are not restrictive. Provided are methods and systems for managing encryption keys for content (e.g., content items). Content items can be assigned to a partition of a plurality of partitions, with each partition corresponding to a corresponding time of encryption key rotation. A partition can be a logical grouping of content items, or a logical grouping of portions of a content item. Content items can be grouped by, for example, according to a class of content, a genre or category of content, or according to other attributes. Encryption key rotation can be a process of discontinuing use of one encryption key in favor of another. A request for a manifest associated with a content item can be sent by a user device and can be received by an edge device, for example. In response to determining that a valid instance of the manifest is not stored, a request for a valid instance of the manifest can be transmitted, for example by the edge device to a manifest server. A valid instance of a manifest is a manifest having an encryption key that is not due for rotation. A valid instance of the manifest can be received by the edge device. The valid instance of the manifest can comprise an entry describing one or more attributes of a digital rights management (DRM) scheme, hereinafter referred to as a DRM entry. The DRM entry can be associated with a first encryption key and a cache control header (e.g., the Cache-Control header used in HyperText Transfer Protocol (HTTP)) based on the corresponding time of encryption key rotation. The cache control header can describe one or more attributes used by the user device in caching the manifest, e.g., how long to cache the manifest, when to delete the manifest from the cache. The valid instance of the manifest can be transmitted to the user device.

The user device can utilize the valid instance of the manifest to retrieve/receive one or more content segments of the content items. The one or more content segments can be encrypted according to the first encryption key. When it is determined that the corresponding time of encryption key rotation has occurred, another manifest comprising a DRM entry associated with a second encryption key can be requested by and/or generated/transmitted to the user device. At least one second content segment of the content item encrypted according to the second encryption key can be transmitted to the user device. The user device can utilize the another manifest to continue to retrieve/receive one or more content segments of the content items encrypted using the second encryption key.

DETAILED DESCRIPTION

In various instances, this detailed description may refer to content items (which may also be referred to as “content,” “content data,” “content information,” “content asset,” “multimedia asset data file,” or simply “data” or “information”). In some instances, content items can comprise any information or data that may be licensed to one or more individuals (or other entities, such as business or group). In various embodiments, content may include electronic representations of video, audio, text and/or graphics, which may include but is not limited to electronic representations of videos, movies, or other multimedia, which may include but is not limited to data files adhering to MPEG2, MPEG, MPEG4 UHD, HDR, 4k, Adobe® Flash® Video (FLV) format or some other video file format whether such format is presently known or developed in the future. In various embodiments, the content items described herein may include electronic representations of music, spoken words, or other audio, which may include but is not limited to data files adhering to the MPEG-1 Audio Layer 3 (MP3) format, Adobe®, CableLabs 1.0, 1.1, 3.0, AVC, HEVC, H.264, Nielsen watermarks, V-chip data and Secondary Audio Programs (SAP). Sound Document (.ASND) format or some other format configured to store electronic audio whether such format is presently known or developed in the future. In some cases, content may include data files adhering to the following formats: Portable Document Format (PDF), Electronic Publication (EPUB) format created by the International Digital Publishing Forum (IDPF), JPEG (JPG) format, Portable Network Graphics (PNG) format, dynamic ad insertion data (.csv), Adobe® Photoshop® (PSD) format or some other format for electronically storing text, graphics and/or other information whether such format is presently known or developed in the future. In some embodiments, content items may include any combination of the above-described examples.

In various instances, this detailed disclosure may refer to consuming content or to the consumption of content, which may also be referred to as “accessing” content, “providing” content, “viewing” content, “listening” to content, “rendering” content, or “playing” content, among other things. In some cases, the particular term utilized may be dependent on the context in which it is used. For example, consuming video may also be referred to as viewing or playing the video. In another example, consuming audio may also be referred to as listening to or playing the audio.

Note that in various instances this detailed disclosure may refer to a given entity performing some action. It should be understood that this language may in some cases mean that a system (e.g., a computer) owned and/or controlled by the given entity is actually performing the action.

The present disclosure relates to managing encryption keys for content (e.g., content items). Content items can be assigned to a respective one of plurality of partitions, or other logical groupings as can be appreciated. For example, content items can be assigned to the plurality of partitions according to a class of content, a genre or category of content, or according to other attributes. Each partition of content can be assigned a corresponding time of encryption key rotation. A time of encryption key rotation indicates a time at which one or more first encryption keys used to encrypt transmissions of content items in a respective partition is no longer used. Instead, at least one second encryption key is used to encrypt transmissions of content items in the respective partition. By assigning different times of encryption key rotation to each partition, the computational burden of associating new encryption keys with content items is distributed over time.

Given that the times of encryption key rotation are known, a manifest can be generated with a header indicating the next time of encryption key rotation. For example, a cache control header can be included in a manifest, with the cache control header indicating the next time of encryption key rotation. In response to a request for a manifest associated with a content item, it can be determined whether a valid instance of the manifest is stored, e.g., stored in a cache. For example, determining whether the valid instance of the manifest is stored can include determining that the next time of encryption key rotation as indicated in the header of a stored manifest has not passed. A valid instance of a manifest is a manifest having an encryption key that is not due for rotation. If a valid instance of the manifest is stored, the valid instance of the manifest can be transmitted to a user device. Otherwise, if a valid instance of the manifest is not stored, a request can be transmitted, e.g., to a packager, for a valid instance of the manifest. The packager can generate a valid instance of the manifest comprising a digital rights management (DRM) entry corresponding to the encryption key currently associated with the content item. The valid instance of the manifest can also comprise a header, e.g., a cache control header, indicating the next time of encryption key rotation. The valid instance of the manifest can then be transmitted to the user device. The valid instance of the manifest can also be stored, e.g., in a cache, such that subsequent requests for the manifest(s) received before the next time of encryption key rotation can be fulfilled using a stored valid instance of the manifest.

FIG.1illustrates various aspects of an exemplary system in which the present methods and systems can operate. Those skilled in the art will appreciate that present methods may be used in systems that employ both digital and analog equipment. One skilled in the art will appreciate that provided herein is a functional description and that the respective functions can be performed by software, hardware, or a combination of software and hardware.

A system100can comprise a central location101(e.g., a headend), which can receive content (e.g., data, input programming, and the like) from multiple sources. The central location101can combine the content from the various sources and can distribute the content to user (e.g., subscriber) locations (e.g., location119) via a network116.

The central location101can receive content from a variety of sources102a,102b,102c. The content can be transmitted from the source to the central location101via a variety of transmission paths, including wireless (e.g. satellite paths103a,103b) and a terrestrial path104. The central location101can also receive content from a direct feed source106via a direct line105. Other input sources can comprise capture devices such as a video camera109or a server110. The signals provided by the content sources can include a single content item or a multiplex that includes several content items.

The central location101can comprise one or a plurality of receivers111a,111b,111c,111dthat are each associated with an input source. For example, MPEG encoders such as an encoder112, are included for encoding local content or a video camera109feed. A switch113can provide access to the server110, which can be a Pay-Per-View server, a data server, an internet router, a network system, a phone system, and the like. Some signals may require additional processing, such as signal multiplexing, prior to being modulated. Such multiplexing can be performed by a multiplexer (mux)114.

The central location101can comprise one or a plurality of modulators115for interfacing to a network116. The modulators115can convert the received content into a modulated output signal suitable for transmission over a network116. The output signals from the modulators115can be combined, using equipment such as a combiner117, for input into the network116. The network116can comprise a content delivery network, a content access network, and/or the like. For example, the network116can be configured to provide content from a variety of sources using a variety of network paths, protocols, devices, and/or the like. The content delivery network and/or content access network can be managed (e.g., deployed, serviced) by a content provider, a service provider, and/or the like.

A control system118can permit a system operator to control and monitor the functions and performance of the system100. The control system118can interface, monitor, and/or control a variety of functions, including, but not limited to, the channel lineup for the television system, billing for each user, conditional access for content distributed to users, and the like. The control system118can provide input to the modulators for setting operating parameters, such as system specific MPEG table packet organization or conditional access information. The control system118can be located at the central location101or at a remote location.

The network116can distribute signals from the central location101to user locations, such as a user location119. The network116can comprise an optical fiber network, a coaxial cable network, a hybrid fiber-coaxial network, a wireless network, a satellite system, a direct broadcast system, an Ethernet network, a high-definition multimedia interface network, universal serial bus network, or any combination thereof.

A multitude of users can be connected to the network116at one or more of the user locations. At the user location119, a media device120can demodulate and/or decode, if needed, the signals for display on a display device121, such as on a television set (TV) or a computer monitor. For example, the media device120can comprise a demodulator, decoder, frequency tuner, and/or the like. The media device120can be directly connected to the network (e.g., for communications via in-band and/or out-of-band signals of a content delivery network) and/or connected to the network116via a communication terminal122(e.g., for communications via a packet switched network). The media device120can comprise a set-top box, a digital streaming device, a gaming device, a media storage device, a digital recording device, a combination thereof, and/or the like. The media device120can comprise one or more applications, such as content viewers, social media applications, news applications, gaming applications, content stores, electronic program guides, and/or the like. Those skilled in the art will appreciate that the signal can be demodulated and/or decoded in a variety of equipment, including the communication terminal122, a computer, a TV, a monitor, or satellite dish.

The communication terminal122can be located at the user location119. The communication terminal122can be configured to communicate with the network116. The communications terminal122can comprise a modem cable modem), a router, a gateway, a switch, a network terminal (e.g., optical network unit), and/or the like. The communications terminal122can be configured for communication with the network116via a variety of protocols, such as internet protocol, transmission control protocol, file transfer protocol, session initiation protocol, voice over internet protocol, and/or the like. For example, for a cable network, the communication terminal122can be configured to provide network access via a variety of communication protocols and standards, such as Data Over Cable Service Interface Specification.

The user location119can comprise a first access point123, such as a wireless access point. The first access point123can be configured to provide one or more wireless networks in at least a portion of the user location119. The first access point123can be configured to provide access to the network116to devices configured with a compatible wireless radio, such as a mobile device124, the media device120, the display device121, or other computing devices (e.g., laptops, sensor devices, security devices). For example, the first access point123can provide a user managed network (e.g., local area network), a service provider managed network (e.g., public network for users of the service provider), and/or the like. It should be noted that in some configurations, some or all of the first access point123, the communication terminal122, the media device120, and the display device121can be implemented as a single device.

The user location119may not be fixed. By way of example, a user can receive content from the network116on the mobile device124. The mobile device124can comprise a laptop computer, a tablet device, a computer station, a personal data assistant (PDA), a smart device (e.g., smart phone, smart apparel, smart watch, smart glasses), GPS, a vehicle entertainment system, a portable media player, a combination thereof, and/or the like. The mobile device124can communicate with a variety of access points (e.g., at different times and locations or simultaneously if within range of multiple access points). For example, the mobile device124can communicate with a second access point125. The second access point125can be a cell tower, a wireless hotspot, another mobile device, and/or other remote access point. The second access point125can be within range of the user location119or remote from the user location119. For example, the second access point125can be located along a travel route, within a business or residence, or other useful locations (e.g., travel stop, city center, park).

The system100can comprise an application device126. The application device126can be a computing device, such as a server. The application device126can provide services related to applications. For example, the application device126can comprise an application store. The application store can be configured to allow users to purchase, download, install, upgrade, and/or otherwise manage applications. For example, the application device126can be configured to allow users to download applications to a device, such as the mobile device124, communications terminal122, the media device120, the display device121, and/or the like. The application device126can run one or more application services to provide data, handle requests, and/or otherwise facilitate operation of applications for the user.

The system100can comprise one or more content source(s)127. The content source(s)127can be configured to provide content (e.g., video, audio, games, applications, data) to the user. The content source(s)127can be configured to provide streaming media, such as on-demand content (e.g., video on-demand), content recordings, and/or the like. For example, the content source(s)127can be managed by third party content providers, service providers, online content providers, over-the-top content providers, and/or the like. The content can be provided via a subscription, by individual item purchase or rental, and/or the like. The content source(s)127can be configured to provide the content via a packet switched network path, such as via an internet protocol (IP) based connection. The content can be accessed by users via applications, such as mobile applications, television applications, set-top box applications, gaming device applications, and/or the like. An example application can be a custom application (e.g., by content provider, for a specific device), a general content browser (e.g., web browser), an electronic program guide, and/or the like.

The system100can comprise an edge device128. The edge device128can be configured to provide content, services, and/or the like to the user location119. For example, the edge device128can be one of a plurality of edge devices distributed across the network116. The edge device128can be located in a region proximate to the user location119. A request for content from the user can be directed to the edge device128(e.g., due to the location of the edge device and/or network conditions). The edge device128can be configured to package content for delivery to the user (e.g., in a specific format requested by a user device), provide the user a manifest (e.g., or other index file describing segments of the content), provide streaming content (e.g., unicast, multicast), provide a file transfer, and/or the like. For example, the edge device128can include a packager129configured to generate manifests for transmission to a user device. The edge device128can also include a key manager130to determine which encryption keys should be used to encrypt content transmitted by the edge device128to a user device. The packager129can encrypt content segments of a content item using the encryption keys indicated by the key manager130. The encrypted content segments can then be transmitted by the edge device128to a user device. Although the packager129and key manager130are shown as components of the edge device128, it is understood that the packager and key manager130can be disposed remotely from the edge device128. The edge device128can cache or otherwise store content (e.g., frequently requested content) to enable faster delivery of content to users. For example, the edge device128can cache or otherwise store manifests generated by the packager129and/or encrypted instances of content segments.

For example, a request for a manifest associated with a content item can be received by the edge device128from a user device (e.g., the media device120). The content item can be assigned to one of a plurality of partitions of content items, with each partition having a corresponding time of encryption key rotation. Although the following discussion describes partitions as including one or more content items, it is understood that portions of content items can also be assigned to and/or associated with a partition. For example, one or more segments of a content item can be assigned to a first partition. One or more other segments of the content item can be assigned to a second partition.

The time of encryption key rotation indicates a time at which one or more first encryption keys used to encrypt transmissions of content items in a respective partition are no longer used. After the time of encryption key rotation, at least one second encryption key is used to encrypt transmissions of content items (e.g., segments) assigned to a respective partition. The corresponding times of encryption key rotation for each of the partitions can be separated by a predefined interval, e.g., twelve hours, one day, or two days. For example, given 28 partitions of content items, a first partition can be assigned a time of encryption key rotation on the first day of every month, a second partition can be assigned a time of encryption key rotation on the second day of every month, etc. The content items can be partitioned according to a class of content, genre, length of content, frequency of access, or according to other criteria.

In response to receiving the request for the manifest associated with the content item, the edge device128can determine if a valid instance of the manifest is stored, e.g., in a cache. For example, the edge device128can determine if a manifest matching the requested manifest is stored in the cache. As another example, the edge device128can determine if a time indicated in cache control data of a stored manifest, e.g., a cache control header, corresponding to a time of encryption key rotation has passed. If a valid instance of the manifest is stored, the valid instance of the manifest can be loaded, e.g., from the cache, and transmitted to the user device.

Otherwise, if a valid instance of the manifest is not stored, the edge device128can transmit a request to the packager129for a valid instance of the manifest. In response to the request for a valid instance of the manifest, the packager129can generate a valid instance of the manifest. For example, generating a valid instance of the manifest can include transmitting, e.g., by the packager129to the key manager130, a request for an encryption key corresponding to the content item associated with the manifest.

In response to the request for the encryption key, the key manager130can provide a previously generated encryption key corresponding to the content item. The key manager130can also generate an encryption key for the content item. For example, the key manager130can generate the encryption key for the content item based on a respective one of the partitions to which the content item is assigned, a type or version digital rights management (DRM) type to be applied to the content item, the corresponding time of encryption key rotation, or another factor. The key manager130can then transmit the encryption key to the packager129. The key manager130can also transmit DRM metadata associated with the encryption key to the packager129facilitating generating the valid instance of the manifest. The DRM metadata can include an identifier for the encryption key, a decryption key corresponding to the encryption key, an identifier for the decryption key corresponding to the encryption key, an identifier of a DRM type or version associated with the content item, or the corresponding time of encryption key rotation for the partition in which the content item is included.

The packager129can then generate a valid instance of the manifest. The valid instance of the manifest can include the encryption key and/or the DRM metadata received from the key manager130. The valid instance of the manifest can include cache control data matching or otherwise corresponding to the corresponding time of encryption key rotation for the content item. The cache control data can be included in a header of the manifest. For example, the cache control data can comprise a cache control header of the manifest. By including the cache control data, a user device in possession of the manifest can determine when the corresponding time of encryption key rotation has occurred. Thus, the user device can transmit a request for a new manifest, an update to a stored manifest, or for an updated encryption/decryption key, in response to the corresponding time of encryption key rotation occurring. This provides advantages over existing solutions where a user device may not be configured to determine that an encryption key has expired or has been deprecated until a failed attempt to decrypt a content segment encrypted by a new encryption key.

The valid instance of the manifest can then be transmitted, e.g., by the packager129, to the edge device128. The edge device128can store the received valid instance of the manifest in a cache to facilitate responding to subsequent requests for the manifest. For example, the edge device128can store the valid instance of the manifest in the cache of the edge device128until a time indicated by the cache control data (e.g. the cache control header) of the valid instance of the manifest.

The edge device128can transmit at least one content segment of a content item to a user device. For example, a user device (e.g., the media device120) can generate requests for content segments based on Uniform Resource Locators (URLs) indicated in a first manifest. The edge device128can then transmit at least one requested content segment to the user device. The at least one requested content segment can be encrypted according to a first encryption key. For example, the packager129can encrypt the requested at least one content segment using the first encryption key, while the first manifest facilitates decryption of the requested at least one content segment by the user device. The first manifest can facilitate decryption of the at least one content segment by including, where symmetric key encryption is used, the first encryption key or an identifier of the first encryption key. The first manifest can also facilitate decryption of the at least one content segment by including, where asymmetric key encryption is used, a decryption key or an identifier of a decryption key corresponding to the first encryption key.

During a transmission of content segments of a content item to a user device, the time of encryption key rotation for the content item can occur. The edge device128can determine that the time of encryption key rotation has occurred in response to a request for a manifest associated with the content item or in response to a request for a content segment of the content item. In response to determining that the time of encryption key rotation has occurred, the edge device128can transmit a manifest to the user device corresponding to a second encryption key. For example, the edge device128can transmit a request to the packager129to generate a manifest. The generated manifest can comprise DRM metadata associated with a second encryption key. The generated manifest can also comprise a header corresponding to a next time of encryption key rotation for the content item. The header can comprise cache control data, e.g., a cache control header. The generated manifest can then be transmitted to the user device. The edge device128can then transmit, e.g., to the user device, content segments encrypted, e.g., by the packager129, using the second encryption key. The user device can be configured to maintain, e.g., in a butler, a duration of content segments exceeding an estimated amount of time to request and/or receive the generated manifest, e.g., five seconds of content segments, ten seconds of content segments, etc. The estimated amount of time to request and/or receive the generated manifest can be determined based on network conditions, e.g. one or more round trip times, an estimated bandwidth of the user device. Thus, the user device can continue to render previously received content segments while requesting and/or receiving an updated manifest, prevent a user of the user device from experiencing perceptible rendering errors.

The edge device128can determine that a transmission of content segments of a content item is within a first predefined duration relative to the time of encryption key rotation for the content item. The first predefined duration can be based on a duration of the content item, e.g., the duration, twice the duration, three times the duration of the content item. Thus, the edge device128can determine that the time of encryption key rotation for the content item may occur during transmission of content segments of the content item. The edge device128can store, e.g., in a cache, one or more content segments encrypted using a first encryption key. The one or more content segments encrypted using a first encryption key can be stored for a second predefined duration after the corresponding time of encryption key rotation. The second predefined duration can be based on a duration of the content item, e.g., the duration, twice the duration, three times the duration of the content item. The first encryption key corresponds to a period before the time of encryption key rotation. Thus, a user device requesting content segments using a manifest corresponding to the first encryption key would be able to receive decryptable content segments from the edge device128after the time of encryption key rotation, thereby preventing perceptible errors in rendering content segments by a user device not having the second encryption key.

The network116can comprise a network component131. The network component131can comprise any device, module, and/or the like communicatively coupled to the network116. For example, the network component131can comprise a router, a switch, a splitter, a packager, a gateway, a encoder, a storage device, a multiplexer, a network access location (e.g., tap), physical link, and/or the like.

FIG.2is an example communications flow diagram200. Beginning at step202, a user device203transmits, to the edge device128, a request for a manifest associated with a content item. The content item can be included in one of a plurality of partitions of content items, with each partition having a corresponding time of encryption key rotation and each of partition being associated with one or more content items or one or more portions of content items. The time of encryption key rotation indicates a time at which one or more first encryption keys used to encrypt transmissions of content items in a respective partition are no longer used. Instead, at least one second encryption key is used to encrypt transmissions of content items in the respective partition. The corresponding times of encryption key rotation for each of the partitions can be separated by a predefined interval, e.g., twelve hours, one day, or two days. For example, given 28 partitions of content items, a first partition can be assigned a time of encryption key rotation on the first day of every month, a second partition can be assigned a time of encryption key rotation on the second day of every month, etc. The content items can be partitioned according to a class of content, genre, length of content, frequency of access, or according to other criteria.

In response to receiving the request for the manifest associated with the content item, the edge device128, at step204, can determine that a valid instance of the manifest is not stored, e.g., in a cache. For example, the edge device128can determine if a manifest matching the requested manifest is not stored in the cache. As another example, the edge device128can determine if a time indicated in a header of a stored manifest, e.g., a cache control header, corresponding to a time of encryption key rotation has passed. The edge device128, at step206, can transmit a request to the packager129for a valid instance of the manifest. In response to the request for a valid instance of the manifest, the packager129can transmit, to the key manager130, a request for an encryption key corresponding to the content item associated with the manifest.

In response to the request for the encryption key, at step210, the key manager130can generate an encryption key for the content item. For example, the key manager130can generate the encryption key for the content item based on a respective one of the partitions into which the content item is included, a type or version digital rights management (DRM) type to be applied to the content item, the corresponding time of encryption key rotation, or another factor. The key manager130can then, at step212, transmit the encryption key to the packager129. The key manager130can also transmit, during step212, DRM metadata associated with the encryption key to the packager129facilitating generating a valid instance of the manifest. The DRM metadata can include an identifier for the encryption key, a decryption key corresponding to the encryption key, an identifier for the decryption key corresponding to the encryption key, an identifier of a DRM type or version associated with the content item, or the corresponding time of encryption key rotation for the partition in which the content item is included.

The packager129can then generate a valid instance of the manifest at step214. The valid instance of the manifest can include the encryption key and/or the DRM metadata received from the key manager130. The valid instance of the manifest can include a headermatching or otherwise corresponding to the corresponding time of encryption key rotation for the content item. The header can comprise cache control data, e.g., a cache control header. The valid instance of the manifest can then be transmitted, e.g., by the packager129, to the edge device128at step216. The edge device128can then transmit the valid instance of the manifest to the user device203at step218.

FIG.3is a flowchart300of an example method. Beginning with step302, a request for a manifest associated with a content item can be received, e.g. by the edge device128from a user device. The content item can be included in one of a plurality of partitions of content items, with each partition having a corresponding time of encryption key rotation. The time of encryption key rotation indicates a time at which one or more first encryption keys used to encrypt transmissions of content items in a respective partition are no longer used. Instead, at least one second encryption key is used to encrypt transmissions of content items in the respective partition. The corresponding times of encryption key rotation for each of the partitions can be separated by a predefined interval, e.g., twelve hours, one day, or two days. For example, given 28 partitions of content items, a first partition can be assigned a time of encryption key rotation on the first day of every month, a second partition can be assigned a time of encryption key rotation on the second day of every month, etc. The content items can be partitioned according to a class of content, genre, length of content, frequency of access, or according to other criteria.

In response to receiving the request for the manifest associated with the content item, at step304, it can be determined, e.g., by the edge device128, if a valid instance of the manifest is stored, e.g., in a cache. For example, determining if a valid instance of the manifest is stored can comprise determining if a manifest matching the requested manifest is stored in the cache. As another example, determining if a valid instance of the manifest is stored can comprise determining if a time indicated in a stored manifest, e.g., indicated in a cache control header, corresponding to a time of encryption key rotation has passed. If the valid instance of the manifest is stored, the method can advance to step306where a valid instance of the manifest can be loaded, e.g., from the cache by the edge device128, and transmitted to the user device.

Otherwise, if a valid instance of the manifest is not stored, the method can advance to step308where the edge device128can transmit a request, e.g., to the packager129, for a valid instance of the manifest. At step310, the valid instance of the manifest can be received, (e.g, by the edge device129from the packager129. The valid instance of the manifest can include an encryption key and/or DRM metadata. The DRM metadata can include an identifier for the encryption key, a decryption key corresponding to the encryption key, an identifier for the decryption key corresponding to the encryption key, an identifier of a DRM type or version associated with the content item, the corresponding time of encryption key rotation for the partition in which the content item is included, combinations thereof, and the like. The valid instance of the manifest can include a header or other data matching or otherwise corresponding to the corresponding time of encryption key rotation for the content item. The header can include cache control data, e.g., a cache control header. The valid instance of the manifest can then be transmitted, e.g., by the edge device128to the user device, at step312.

FIG.4is a flowchart400of an example method. Beginning with step402, each of a plurality of content items is assigned to a respective partition of a plurality of partitions, e.g., by a key manager130. A partition can comprise a logical grouping or classification into which one or more content items are assigned. Each of the plurality of content items can be assigned to a respective partition of the plurality of partitions based on a class of content, genre of content, frequency of access, recency of access or creation, length of content, or another factor. Next, in step404, for each partition, a corresponding time of encryption key rotation can be determined. The time of encryption key rotation indicates a time at which one or more first encryption keys used to encrypt transmissions of content items in a respective partition, e.g., by a packager129, are no longer used. Instead, at least one second encryption key is used, e.g. by the packager129, to encrypt transmissions of content items in the respective partition. The corresponding times of encryption key rotation for each of the partitions can be separated by a predefined interval, e.g., twelve hours, one day, or two days. For example, given 28 partitions of content items, a first partition can be assigned a time of encryption key rotation on the first day of every month, a second partition can be assigned a time of encryption key rotation on the second day of every month, etc.

Next, at step406, at least one manifest can be generated, e.g., by the packager129. Generating the valid instance of the manifest can include transmitting, e.g., by the packager129to the key manager130, a request for an encryption key corresponding to the content item associated with the manifest. The encryption key can be generated, e.g., by the key manager130, based on a respective one of the partitions into which a content item associated with the at least one manifest is included, a type or version digital rights management (DRM) type to be applied to the content item, the corresponding time of encryption key rotation, or another factor.

The at least one manifest can be generated, e.g., by the packager129, to include the encryption key and/or DRM metadata. The DRM metadata can include an identifier for the encryption key, a decryption key corresponding to the encryption key, an identifier for the decryption key corresponding to the encryption key, an identifier of a DRM type or version associated with the content item associated with the at least one manifest, or the corresponding time of encryption key rotation for the partition in which the content item associated with the manifest is included. At least one manifest can be generated, e.g., by the packager129, to include data (e.g. a header, such as a cache control header) matching or otherwise corresponding to the corresponding time of encryption key rotation for the content item.

FIG.5is a flowchart500of an example method. Beginning with step502, at least one content segment of a content item can be transmitted, e.g., by an edge device128to a user device. The at least one content segment can be transmitted in response to a request for the at least one content segment received from the user device. The at least one content segment can be encrypted according to a first encryption key, e.g., by the packager129. The first encryption key can correspond to a partition of a plurality of partitions into which the content item is assigned. For example, the content item can be included in a plurality of content items, where each of the plurality of content items is assigned to one of the plurality of partitions. Each of the plurality of content items can be assigned to one of the plurality of partitions based on a content type, a duration of the respective content item, or according to other criteria. The first encryption key can be associated with a corresponding time of encryption key rotation as determined by the partition. For example, each of the plurality of partitions can correspond to one of a plurality of times of encryption key rotation. Each of the plurality of times of encryption key rotation can be separated by a predefined interval, e.g., twelve hours, one day, two days.

At step503the user device can be caused, e.g., by the edge device128, to buffer a duration of the at least one first content segment. For example, the duration of the content item to be buffered by the content item can exceed an amount of time for the user device to receive a decryption key corresponding to a second encryption key, e.g., from a key manager130. This allows the user device to render and/or display buffered content segments encrypted by the first encryption key as the user device acquires the second encryption key as is set forth below. The duration can be based on an estimated time for the user device to receive the decryption key. The estimated time can be based on current network conditions, previous times for the user device or other user devices to receive decryption keys, or otherwise determined. The duration can also be a duration predefined according to desired results.

At step504it can be determined, e.g. by the edge device128, that the time of encryption key rotation for the content item has occurred. For example, the edge device128can determine that a time indicated in cache control data (e.g., a cache control header) of one or more cached content segments of the content item has passed. As another example, the edge device128can determine that a time indicated in a manifest associated with the content item has passed. In response to determining that the time of encryption key rotation has occurred, at step506, a manifest corresponding to a second encryption key can be transmitted, e.g., by the edge device128to a user device. For example, the edge device128can transmit a request to the packager129to generate a manifest. The generated manifest can comprise DRM metadata associated with a second encryption key. The generated manifest can also comprise a header, e.g., a cache control header, corresponding to a next time of encryption key rotation for the content item. The generated manifest can then be transmitted, e.g., by the edge device128to the user device. The generated manifest can facilitate an acquisition of the second encryption key by the user device. At step508, at least one second content segment can be transmitted. e.g., by the edge device128, that are encrypted, e.g., by the packager129, using the second encryption key.

The methods and systems can be implemented on a computer101as illustrated inFIG.6and described below. By way of example, the edge device129ofFIG.1can be a computer as illustrated inFIG.6. Similarly, the methods and systems disclosed can utilize one or more computers to perform one or more functions in one or more locations.FIG.6is a block diagram illustrating an exemplary operating environment for performing the disclosed methods. This exemplary operating environment is only an example of an operating environment and is not intended to suggest any limitation as to the scope of use or functionality of operating environment architecture. Neither should the operating environment be interpreted as having any dependency or requirement relating to any one or combination of components illustrated in the exemplary operating environment.

Further, one skilled in the art will appreciate that the systems and methods disclosed herein can be implemented via a general-purpose computing device in the form of a computer601. The components of the computer601can comprise, but are not limited to, one or more processors603, a system memory612, and a system bus613that couples various system components including the one or more processors603to the system memory612. The system can utilize parallel computing.

The system bus613represents one or more of several possible types of bus structures, including a memory bus or memory controller, a peripheral bus, an accelerated graphics port, or local bus using any of a variety of bus architectures. By way of example, such architectures can comprise an Industry Standard Architecture (ISA) bus, a Micro Channel Architecture (MCA) bus, an Enhanced ISA (EISA) bus, a Video Electronics Standards Association (VESA) local bus, an Accelerated Graphics Port (AGP) bus, and a Peripheral Component Interconnects (PCI), a PCI-Express bus, a Personal Computer Memory Card Industry Association (PCMCIA), Universal Serial Bus (USB) and the like. The bus613, and all buses specified in this description can also be implemented over a wired or wireless network connection and each of the subsystems, including the one or more processors603, a mass storage device604, an operating system605, content software606, content data607, a network adapter608, the system memory612, an Input/Output Interface610, a display adapter609, a display device611, and a human machine interface602, can be contained within one or more remote computing devices614a,b,cat physically separate locations, connected through buses of this form, in effect implementing a fully distributed system.

The computer601typically comprises a variety of computer readable media. Exemplary readable media can be any available media that is accessible by the computer601and comprises, for example and not meant to be limiting, both volatile and non-volatile media, removable and non-removable media. The system memory612comprises computer readable media in the form of volatile memory, such as random access memory (RAM), and/or non-volatile memory, such as read only memory (ROM). The system memory612typically contains data such as the content data607and/or program modules such as the operating system605and the content software606that are immediately accessible to and/or are presently operated on by the one or more processors603.

Optionally, any number of program modules can be stored on the mass storage device604, including by way of example, the operating system605and the content software606. Each of the operating system605and the content software606(or some combination thereof can comprise elements of the programming and the content software606. The content data607can also be stored on the mass storage device604. The content data607can be stored in any of one or more databases known in the art. Examples of such databases comprise, DB2®, Microsoft® Access, Microsoft® SQL Server, Oracle®, mySQL, PostgreSQL, and the like. The databases can be centralized or distributed across multiple systems.

The user can enter commands and information into the computer601via an input device (not shown). Examples of such input devices comprise, but are not limited to, a keyboard, pointing device (e.g., a “mouse”), a microphone, a joystick, a scanner, tactile input devices such as gloves, and other body coverings, and the like. These and other input devices can be connected to the one or more processors603via the human machine interface602that is coupled to the system bus613, but can be connected by other interface and bus structures, such as a parallel port, game port, an IEEE 1394 Port (also known as a Firewire port), a serial port, or a universal serial bus (USB).

The display device611can also be connected to the system bus613via an interface, such as the display adapter609. It is contemplated that the computer601can have more than one display adapter609and the computer601can have more than one display device611. For example, the display device611can be a monitor, an LCD (Liquid Crystal Display), or a projector. In addition to the display device611, other output peripheral devices can comprise components such as speakers (not shown) and a printer (not shown) which can be connected to the computer601via the Input/Output Interface610. Any step and/or result of the methods can be output in any form to an output device. Such output can be any form of visual representation, including, but not limited to, textual, graphical, animation, audio, tactile, and the like. The display device611and computer601can be part of one device, or separate devices.

The computer601can operate in a networked environment using logical connections to one or more remote computing devices614a,b,c. By way of example, a remote computing device can be a personal computer, portable computer, smartphone, a server, a router, a network computer, a peer device or other common network node, and so on. Logical connections between the computer601and a remote computing device614a,b,ccan be made via a network615, such as a local area network (LAN) and/or a general wide area network (WAN). Such network connections can be through the network adapter608. The network adapter608can be implemented in both wired and wireless environments. Such networking environments are conventional and commonplace in dwellings, offices, enterprise-wide computer networks, intranets, and the Internet.