# Patent

## Title
Systems and methods for performing transport I/O

## Abstract

Systems and methods for implementing a Transport I/O system are described. Network encrypted content may be received by a device. The device may provide the network encrypted content to a secure processor, such as, for example, a smart card. The secure processor obtains a network control word that may be used to decrypt the network encrypted content. The secure processor may decrypt the network encrypted content to produce clear content. In embodiments, the secure processor may then use a local control word to generate locally encrypted content specific to the device. The device may then receive the locally encrypted content from the secure processor and proceed to decrypt the locally encrypted content using a shared local encryption key. The Transport I/O system ensures the protection of the network control word by maintaining the network control word on the secure processor.

## Background
BACKGROUND
Digital Video Broadcasting (DVB) is an internationally recognized standard for transmitting digital television over cable, satellite, and other transmission mediums. A weakness of the DVB architecture is that the network control word used to decrypt content is easily shared over the Internet allowing non-subscribers access to broadcasted content. It is with respect to this general environment that embodiments of the present invention have been contemplated.
SUMMARY
Embodiments of the present disclosure relate to systems and methods to access content using a Transport I/O system. In embodiments, a secure processor receives network encrypted content. The secure processor may decrypt the network encrypted content using a network control word. In such embodiments, the network control word never leaves the secure processor and, thus, is protected from interception by an unauthorized user.
In further embodiments, after decrypting the network encrypted content, the secure processor may re-encrypt the content using a local control word to produce locally encrypted content. The locally encrypted content may be uniquely encrypted for a specific device such as, for example, a set-top-box, a system on a chip, or any other type of device capable of receiving and modifying content. In embodiments, the secure processor provides the locally encrypted content to the device.
The device may receive the locally encrypted content and obtain the local control word. Using the local control word, the device may decrypt the locally encrypted content to produce clear content. The clear content may be processed by the device. For example, the device may display the content or store the content for later use.
This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.



BRIEF DESCRIPTION OF THE DRAWINGS
The same number represents the same element or same type of element in all drawings.
FIG. 1 illustrates a communications system 100 that may be employed with a Transport I/O system to protect content.
FIG. 2 is a flowchart representing an embodiment of a method 200 of performing network content decryption.
FIG. 3 is an embodiment of a method 300 for processing locally encrypted content.
FIG. 4 is an embodiment of a method 400 for receiving and processing protected content using a Transport I/O system.
FIG. 5 is an embodiment of a method 500 that may be employed to reset functionality of a secure device.
FIG. 6 is an embodiment of a packet pacing method 600.
FIG. 7 is an embodiment illustrating the compatibility between an ISO-7816 smart card and a smart card capable of supporting the systems and methods disclosed herein.
FIG. 8 is an embodiment of a secure processing device 800 that may be employed with the systems or to perform the methods disclosed herein.
FIG. 9 is an embodiment of a set-top-box that may be used to perform the Transport I/O system methods and be part of the systems disclosed herein.
FIG. 10 illustrates an embodiment of a computer environment and computer system 1000 for implementing the systems and methods disclosed herein.



DETAILED DESCRIPTION
The various embodiments described herein generally provide systems and methods for protecting streamed content by employing a Transport I/O system. In embodiments, a Transport I/O system can be employed to decrypt content, such as, but not limited to, a network broadcast stream without exposing a network encryption key to an unauthorized party. For example, in an embodiment where a Transport I/O system is operating in a Digital Video Broadcasting environment, a Transport I/O system may maintain a control word on a smart card and use the control word to decrypt a network broadcast on the smart card, rather than providing a decrypted control word to a descrambler that is not part of the smart card. In other embodiments, a Transport I/O system may protect a control word from exposure by applying additional encryption to a control word, securely communicating a control word to another component, etc. One of skill in the art will appreciate that any other means of reducing the risk of exposure of a control word or control words may be employed by a Transport I/O system.
In embodiments, the systems and methods disclosed herein may be practiced in a Digital Video Broadcasting (DVB) compliant system. DVB is a set of internationally accepted open standards for broadcasting digital television. The DVB standards define both the physical layer and the data link layer of a distributed system. There are DVB standards defining the distribution of content over various different mediums. For example, satellite transmissions are defined in the DVB-S, DVB-S2, and DVB-SH specifications. Cable transmission is defined in the DVB-C and DVB-C2 specifications. Terrestrial television transmission is defined in the DVB-T and DVB-T2 specifications for standard television formats and DVB-H and DVB-H2 for the transmission of mobile television, e.g., television for handheld devices such as mobile phones. Microwave transmission is defined in the DVB-MT, DVB-MC, and DVB-MS standards.
In addition to defining the physical and data link layers, the DVB suite of standards includes standards that are used to provide conditional access protection of the transmitted content. Examples include the DVB-CA, DVB-CSA, and DVB-CI standards. Conditional access is a method of protecting content by requiring a device to meet certain criteria before it accesses content. Conditional access plays an important role in ensuring that broadcasted content is made available only to subscribers of a particular broadcast system (e.g., cable and satellite customers, etc.). The general architecture uses a global key, called a network control word (NCW), for performing conditional access. One or more NCW's are used to encrypt data before it is broadcast to subscribers. The NCW's are transmitted by a head-end (e.g., a satellite or cable provider) to subscriber devices in an entitlement control message (ECM). The ECM is generally encrypted before transmission to the subscriber device. The conditional access system of the subscriber devices (e.g., a smart card or other conditional access module whether in hardware or software) decrypts the ECM using information received in an entitlement management message (EMM) transmitted from the head-end. The subscriber device can then use the NCW's to decrypt the content broadcast by the head-end. Generally, a NCW is used for a certain period of time, or a crypto period. Upon expiration of a crypto period a new crypto period begins. The head-end may then transmit a new NCW to a subscriber device(s) and proceed to use the new NCW to encrypt the broadcast content.
One of the main weaknesses of the DVB conditional access architecture is that a NCW can be decrypted and easily shared over the Internet. Because the content is broadcast to many users, the content must be encrypted with the same key (e.g., same network control word) for every subscriber. Thus, once the network control word is discovered, any unauthorized user (e.g., a non-subscriber) with access to the network may use the network control word to decrypt the broadcast content. Generally, the NCW's consists of eight (8) bytes. The duration of a crypto period usually varies between five (5) to sixty (60) seconds. Thus, a non-subscriber may defeat the DVB conditional access architecture based upon the discovery of the eight (8) byte NCW, a task which may be accomplished within the duration of a typical crypto period. Generally, after the NCW is obtained by the smart card the smart card provides the NCW to an external device or component. The external device or component uses the NCW to decrypt the broadcast content. However, the NCW may be intercepted and shared with others, thereby allowing unauthorized sharing of the content.
While the present disclosure describes the Transport I/O system as a solution to the shortcomings of DVB conditional access, one of skill in the art will appreciate that the methods and systems disclosed herein can be practiced to protect content in other types of data transmission streaming and/or broadcasting that are not compliant with the DVB architecture such as, but not limited to, streaming media over the Internet. The systems and methods disclosed herein with respect to the Transport I/O system will now be discussed in detail with respect to the accompanying figures.
FIG. 1 illustrates a communications system 100 that may be employed with a Transport I/O system to protect content. The communications system includes a head-end device 102 that receives content from content providers 104 and distributes the content across a communication network 106 to various recipient devices 108. The recipient devices can access the content and display it to a user. A single recipient device 108 can be any device capable of receiving and decoding a data transmission stream over communication network 106. Such devices include, but are not limited to, mobile phones, smart phones, personal digital assistants (PDAs), satellite or cable set-top-boxes, desktop computers, laptop computers, tablet computers, televisions, radios, a video processing device, or any other device known to the art. In embodiments, recipient devices 108 of subscribers are generally able to access the encryption key used to decrypt the content, while non-subscribers are not able to access the encryption key without circumventing the security measures employed by the head-end device 102 broadcasting the content over the communication network 106.
In embodiments, the head-end 102 may be a distribution point of a cable television provider, the distribution of point of a satellite television provider (e.g., a satellite), a terrestrial wireless network, a server broadcasting content over the Internet, or any type of device capable of distributing content over a communications network. One of skill in the art will appreciate that the head-end device 102 may be any type of device, or a collection of devices (as the case may be), that are capable of receiving, encrypting, and broadcasting content over a network.
In one embodiment, the content broadcast over communications system 100 may be generated by the head-end device 102. In other embodiments, the head-end device 102 may receive content from one or more content providers 104. In such embodiments, the head-end device 102 is in electrical communication with one or more content providers 104. For example, a content provider may be a cable, terrestrial, or satellite television station that transmits content to the head-end device 102 over a wired (e.g., cable, fiber optic, or Internet connection) or wireless connection (e.g., via radio, microwave, or satellite communications). In other embodiments, the content may reside in a datastore that is in electrical communication with the head-end device 102. While FIG. 1 depicts the content providers 104 as being separate entities from the head-end device 102, in other embodiments, the content providers 104 and head-end device 102 may be a single entity.
The head-end device 102 is tasked with distributing the content over a communication network 106 to various recipient devices 108. In embodiments, the communication network 106 may be the Internet, a cable network, a fiber optic network, a satellite communications network, a terrestrial broadcasting network (e.g., networks communicating over radio or microwave transmission mediums), a cellular data network, a wide area network (WAN), a local area network (LAN), a plain old telephone service (POTS) network, the Internet, or any other type of communication network capable of streaming, broadcasting, and/or otherwise facilitating data transmissions between various devices. One of skill in the art will appreciate that the systems and methods disclosed herein can be practiced regardless of the type of communication network used to transmit data between devices. In many cases, the head-end device 102 may broadcast the content in a data transmission stream over the communications network rather than sending content to a particular device. Because the content is being broadcast over the communication network 106, the transmission can be received by any number of devices capable of interacting with the communication network 106. In order to prevent unauthorized users from accessing the broadcasted data transmission stream, the head-end device 102 encrypts the data transmission stream before it is broadcast over the communication network 106. Because the network broadcasted content is made available to multiple devices, a common encryption key (e.g., a network control word) may be used to encrypt the network broadcasted content (e.g., network encrypted content). In embodiments, the network broadcast content may be a network encrypted stream that includes content, such as network encrypted content, and data. In embodiments, the data contain information about the stream such as, but not limited to, encryption information, timing information, compression information, or any other type of information. Although not illustrated in FIG. 1 the communication network may also be used to perform two-way communication between the head-end device 102 and the recipient device or devices 108.
In embodiments, the data transmission stream is encrypted using a one or more keys, such as, but not limited to, a network control work (NCW). The NCW may be used to encrypt the data transmission stream for a certain amount of time (e.g., a crypto period) thereby resulting in the creation of network encrypted content. In embodiments, network encrypted content may be encrypted using a common key (e.g., an NCW) such that the network encrypted content can be decrypted by authorized users (e.g., subscribers). The NCW is shared between head-end device 102 and the various recipient device or devices 108. In one embodiment, communication system 100 may operate according to the DVB architecture. In such embodiments, the NCW may be a control word (CW) that acts as the key used in encrypting the content. In such environment, the head-end 102 may periodically transmit the NCW to the various subscriber devices using an ECM message. Additionally, the head-end 102 transmits an EMM message to the various subscribers which contains information necessary to decrypt the ECM and retrieve the NCW. In such embodiments, the EMM may be decrypted by a secure device or processor, such as a smart card that is part of or connected to the recipient device to retrieve the NCW. The smart card may then provide the NCW to another component that is part of or in communication with the recipient device to decrypt the content. However, once the NCW is sent from the secure device and/or processor, the CW may be intercepted and shared with others to provide unauthorized access to the content.
In embodiments, the Transport I/O system solves this problem by maintaining the decrypted control word in a secure processing device (e.g., on a smart card, secure processor, secure memory, or any other secure device or secure component of a device). In such embodiments, the decrypted CW is maintained on the secure device, thereby preventing the interception and sharing of the CW. In such embodiments, the secure content (e.g., an encrypted broadcast or encrypted content) may be decrypted on the secure processing device. The secure processing device may then provide the clear content (e.g., decrypted content). While the clear content may be intercepted and shared, it may not be as easy to share the content due to the size of the content and the bandwidth required to share the content. In another embodiment, the secure processing device may uniquely encrypt the content for use by a specific device (e.g., a recipient device 108). For example, in such embodiments a method utilizing a local encryption key, or local control word (LCW), may be used to create locally encrypted content. The local control word may be unique to a local device. The secure processor or secure processing device may then provide the locally encrypted content to the local device. Furthermore, in embodiments, the locally encrypted content may be uniquely encrypted for a specific device such as, for example, a set-top-box, a system on a chip, or any other type of device capable of receiving and modifying content.
FIG. 2 is a flowchart representing an embodiment of a method 200 of performing network content decryption. In embodiments, the method 200 may be performed by a secure device or a secure processor. An example of a secure device is a smart card. Flow begins at operation 202 where the network encrypted content is received by the secure device. In embodiments, network secure content may be content encrypted using a NCW. The NCW may be a common control word or encryption key that is used to encrypt and decrypt content sent to multiple users or subscribers. In one embodiment, the network encrypted content may be a single stream of data. In alternate embodiments, the network encrypted content may contain multiple network encrypted streams, such as network encrypted elementary streams. Network encrypted elementary streams may be streams that contain audio data, video data, closed captioned data, or any other type of data. A network encrypted elementary stream may consist of compressed data from a single source, such as a particular network or channel. In embodiments where the network encrypted content may contain multiple network encrypted elementary streams, one or more network encrypted elementary streams may be individually received at operation 202. However, in alternate embodiments, the network encrypted content comprising multiple network encrypted elementary streams may be received at operation 202. In such embodiments, individual network streams may be filtered out, e.g., by performing PID filtering or other type of filtering, to isolate one or more individual network encrypted elementary streams at operation 202. Upon receiving the network encrypted content, flow continues to operation 204 where the network control word is obtained. In one embodiment, the network control word may be a control word provided by the content supplier, such as, but not limited to, a head-end or a server transmitting the content. In embodiments, the network control word may be previously known by the device performing the method 200. In another embodiment, the network control word may be received by the device. In such embodiments, the network control word may be encrypted, and operation 204 may include decrypting the network control word. For example, in embodiments, the network control word may be obtained by decrypting an ECM that contains the network control word. The ECM may be decrypted using information from another message, such as an EMM. While the ECM and EMM messages are part of the DVB architecture, one of skill in the art will appreciate that other content delivery systems and architectures may be employed with the systems and methods disclosed herein.
Flow continues to operation 206 where the network encrypted content (e.g., a network encrypted elementary stream or multiple network encrypted elementary streams) is decrypted using the network control word. In one embodiment, a single network control word may be used to decrypt the network encrypted content. In alternate embodiments, multiple control words may be used to decrypt the network encrypted content such as, for example, when the network encrypted content comprises multiple network encrypted elementary streams that have each been encrypted using a different network control word. In such embodiments, multiple network control words may be obtained at operation 204 and then used to decrypt multiple network elementary streams at operation 206. However, in still other embodiments, a single network control word may be used to encrypt multiple network elementary streams. In such embodiments, a single network control word may be used to decrypt the multiple network encrypted elementary streams. Decryption of the network encrypted content at operation 206 may result in clear content, that is, content that is not protected by encryption. Because operations 202-206 may be performed by a secure device or secure processor, such as, but not limited to, a smart card, the network control word remains on the secure device. By maintaining the network control word on the device, an unauthorized subscriber cannot intercept the network control word that is transmitted between the smart card and a device, such as a set-top-box, thereby impeding access to content by an unauthorized subscriber. In embodiments not shown in FIG. 2 the clear content may be provided by the secure processor for display or storage after decryption step 206. However, in the illustrated embodiment, an additional layer of protection may be added by performing local link encryption. In embodiments, local link encryption may comprise the re-encryption of the clear content using a local control word (LCW). The local control word may be an encryption key that is unique to a specific device. For example, in a set-top-box environment, the LCW may be an encryption key that is only shared with the particular set-top-box that the smart card performing the method 200 may be in communication with. In embodiments, different types of encryption modes may be performed for local link encryption. In one embodiment, not all of the data representing the content may be encrypted using local link encryption. For example, transport mode encryption may be used. In embodiments transport mode encryption comprises a determination as to which bytes of data to encrypt based upon an MPEG2 transport encryption. In another embodiment, Bulk Mode encryption may be performed. In Bulk Mode encryption, all bytes representing the data may be encrypted during local link encryption. Bulk Mode encryption may be utilized to exchange data between devices in a secure manner. For example, Bulk Mode encryption may be used to mix transport input (e.g., content) with internal data that is used by the one or more components participating in encryption/decryption of content. In further embodiments, Bulk Mode encryption may be utilized to support other types of content streams that may provide additional features, such as Internet Protocol television (IPTV) content streams. Selection of the encryption mode may be based upon data that is present in the content or a data stream that includes the content. For example, one or more bits may be a part of or added to the clear content to identify an encryption mode to perform during local link encryption. Furthermore, in embodiments, the encryption algorithm performed during local link encryption may be compliant with the ATIS-08000006 standard. However, one of skill in the art will appreciate that any type of encryption algorithm may be used for local link encryption, so long as the same encryption algorithm is available on both the smart card and the device.
In embodiments, a key setup used to select a key to be used for local link encryption may take place across security boundaries. For example, a key exchange may be made between a smart card and a set-top-box as part of the key setup. An exchanged key may be generated by a secure device, such as a smart card, and transmitted to a specific device that is communicating with the secure device, such as a set-top-box. Because the local link encryption key is specific to a single device, and not a network transmission, interception of the local link encryption key does not provide an unauthorized user the ability to globally access the broadcasted network content. In embodiments, multiple keys may be used for local link encryption. For example, a smart card may be able to simultaneously process multiple input streams and output multiple locally encrypted streams. In such embodiments, each locally encrypted stream may be encrypted using a unique local link encryption key. However, in other embodiments, the same local link encryption key may be used to encrypt each of the locally encrypted streams.
Flow continues to operation 208 where a local control word is obtained. A local control word may be any type of encryption key. In embodiments, the local control word may be an encryption key that is specific to a target device. In embodiments, the local control word may be obtained from ordinary software registers, a hardware key ladder, a random key generator, or from any other source. In one embodiment, the local control word may be dynamically generated and shared with a recipient device. In such embodiments, the key may be generated based upon characteristics of the device. In embodiment, multiple keys may be selected during obtain operation 208. For example, two keys may be selected from a key ladder. A key ladder may store or otherwise identify a plurality of interrelated keys. In embodiments, any type of encryption key or keys, e.g., fixed encryption keys, dynamic encryption keys, randomly generated encryption keys, etc. may be employed with the embodiments disclosed herein.
After obtaining the local control word, flow continues to operation 210 where the network decrypted content is re-encrypted using the local control word to generate locally encrypted content. As was previously discussed, different types of encryption modes and encryption algorithms may be used to encrypt the content at operation 210. In an embodiment, the encryption may be based upon the key obtained at operation 208. In embodiments where multiple keys are obtained, one of the keys may be selected and used during encryption at operation 210. For example, an appropriate key may be selected based upon an identifier in the content. The identifier may be part of the content or may be added to the content or a header associated with the content as it is processed during the method 200. The identifier may be a single bit that identifies an even or an odd key (in embodiments where two keys are obtained). This identifier provides for the automatic selection of a key for use during the encryption process at operation 210.
In further embodiments, in addition to encrypting the content, the size of the content may be increased. It may be beneficial to increase the size of the content in order to make it more difficult for the content to be shared over a network. For example, increasing the content size will require greater bandwidth to properly share the content with unauthorized users over a network. For example, data may be added to a broadcast stream to make it more difficult to process or share with unauthorized users. In embodiments where the content is streamed (e.g., audio and/or video content) non-content data packets may be added to the content stream and the bandwidth rates may be increased. The increase in bandwidth and the addition of non-content data provides additional security for the content when it leaves the secure device and/or secure processor that performs the method 200 by making the content more difficult to share and process. Further details regarding stream expansion are provided in U.S. Pat. No. 8,385,542 entitled, “Methods and Apparatus for Securing Communications Between a Decryption Device and a Television Receiver,” filed on Apr. 27, 2009, which is hereby incorporated by reference in its entirety.
While the embodiment of the method 200 is illustrated as decrypting the network encrypted content, and subsequently locally encrypting the decrypted network encrypted content as two distinct operations, one of skill in the art will appreciate that, in embodiments, the decryption and encryption may be performed sequentially, performed as a single operation, or performed in parallel. In embodiments, a person of skill in the art will appreciate that stream expansion may also be performed in the single decryption/encryption operation. As such, one of skill in the art will appreciate that the method described with respect to FIG. 2 may be performed using fewer or more operations than are illustrated herein.
In further embodiments, the method 200 may operate on stream data. In such embodiments, a network encrypted stream may be received at operation 202, a clear content stream may be generated by decrypting the network encrypted stream at operation 204, and a locally encrypted stream may be generated at operation 212. One of skill in the art will appreciate that the embodiments disclosed herein with respect to FIG. 2 (as well as with respect to FIGS. 3-4) may operate on stream data as well as data transmitted in any other form.
Further to the embodiment illustrated by FIG. 2, after performing the local encryption, flow continues to operation 212 where the locally encrypted content is provided to another device. For example, in a set-top-box environment, a smart card may provide the locally encrypted content to other components of the set-top-box for storage and/or display at operation 212. In a general computing device, the locally encrypted content may be provided from a secure processor to a general processor and/or unprotected memory for storage and/or display at operation 212. One of skill in the art will appreciate that the method 200 provides a solution to the problems described herein by providing locally encrypted content to unsecure components as opposed to providing a control word or encryption key as is generally performed by devices and systems that do not support embodiments of a Transport I/O system as described herein. Furthermore, one of skill in the art will appreciate that the weakest security leak in such content protection systems may occur when data is transmitted from a secure device and/or processor to a general device. However, embodiments disclosed herein address this weakness by providing locally encrypted content and, optionally, content that has its data and bandwidth expanded, thereby making it harder for an unauthorized user to process, share, and access the content even if it is intercepted as it is transmitted within the secure device and/or processor system/architecture.
In one embodiment, the locally encrypted content may be provided as individual locally encrypted elementary streams. For example, in embodiment where multiple network encrypted elementary streams are received and decrypted, the multiple elementary streams may be individually encrypted and returned as individual locally encrypted elementary streams. In an alternate embodiment, the multiple network encrypted elementary streams may be multiplexed into a single output stream. In such embodiments, the single output stream may be locally encrypted and then provided at operation 212. In embodiments, multiple elementary streams may be multiplexed into a single output stream prior to the local encryption performed at operation 210 or after the local encryption operation 210.
FIG. 3 is an embodiment of a method 300 for processing locally encrypted content. In embodiments, the method 300 may be performed by a device such as a set-top-box, a laptop computer, a tablet computer, a smart phone, a television, or any other type of general computing device. Flow begins at operation 302 where the locally encrypted content is received. In embodiments, the locally encrypted content may be received from a secure device and/or secure processor that performed the method 200 described with respect to FIG. 2. For example, in a non-limiting embodiment, the locally encrypted content may be received from a smart card that is in communication with a set-top-box. In another embodiment, the locally encrypted content may be received from a secure processor that is in communication with a general processor and/or general memory.
Upon receiving the locally encrypted content, flow continues to operation 304 where a local control word is obtained. A local control word may be any type of encryption key. In embodiments, the local control word may be an encryption key that is specific to the device performing the method 300. In embodiments, the local control word may be obtained from the smart card using ordinary software registers, a hardware key ladder, a random key generator, or from any other source unique to the device. In one embodiment, the local control word may be received from the secure device and/or processor performing the method 200. In another embodiment, the local control word may be generated by the device performing the method 300. In such embodiments, the local control word may have been previously shared with a secure processing device and/or secure processor that created the locally encrypted content received at operation 302. The local control word may be randomly generated. In embodiments, a single local control word may be used. In other embodiments, multiple local control words may be used. In such embodiments, the local control word may change periodically such that a local control word is discarded for a new local control word after a set period of time.
Flow continues to operation 306 where the locally encrypted content is decrypted using the local control word. Decryption of the locally encrypted content may produce content in the clear that is accessible by an application. One of skill in the art will appreciate that many type(s) of encryption mode(s) and/or algorithm(s) may be employed to decrypt the locally encrypted content. As such, a type of decryption algorithm may be employed at operation 306 to decrypt the content using the local control word. Furthermore, the device performing the decryption may be capable of handling and processing the locally encrypted content despite the increased bandwidth of the locally encrypted content due to non-content data. In such embodiments, decryption of the locally encrypted content at operation 306 may include identifying and removing non-content data from the content. In another embodiment, removal of the non-content data may not take place until the clear content is processed for display or storage.
Flow continues to operation 308 where the clear content is provided. In one embodiment, providing the clear content may include decoding, displaying and or otherwise playing the clear content. For example, the clear content may be displayed on a television, monitor, and or display that may be part of the device or in communication with the device performing the method 300. In another embodiment, providing the clear content may include storing the clear content in data storage that may be part of the device or connected to the device performing the method 300.
In an alternate embodiment, persistent encryption may be performed by not immediately decrypting the locally encrypted content as described in FIG. 3. In such embodiments, persistent encryption may be utilized on content, such as MPEG Transport Packets received from a broadcasted network transmission. In such embodiments, a secure device may still perform network decryption and local link encryption as described in FIG. 2; however, the device that receives the locally encrypted content may not immediately perform local link decryption. Instead, the device receiving the locally encrypted content may store the locally encrypted content, as it is encrypted, for later use. This allows the content to be encrypted for secure local storage, but the secure device can still control when the content is decrypted by, for example, providing a decryption key at a later time.
FIG. 4 is an embodiment of a method 400 for receiving and processing protected content using a Transport I/O system. In embodiments, the method 400 may be performed by a set-top-box, a smartphone, a laptop, a tablet, a television, or any other type of general computing device such as the recipient devices discussed with respect to FIG. 1. In embodiments, the device performing the method 400 may include or be in communication with and/or include a secure processing device and/or secure processor. The secure processing device and/or secure processor may be a removable component of the device. For example, the secure processor may be incorporated within a removable smart card that may be inserted and removed from a device performing the method 400.
Flow begins at operation 402 where network encrypted content is received. Network encrypted content may be received from a head-end device. In embodiments, the network encrypted content may be received over a wireless or wired network. For example, the network encrypted content may be received from a satellite television provider, a cable television provider, from a terrestrial transmission, from a cellular network provider, or from a server over the Internet. In embodiments, the network encrypted content is content that may be transmitted to multiple different devices. As such, the network encrypted content may be encrypted using a network control word that is common to all devices receiving the content. Upon receiving the network encrypted content, flow continues to operation 404 where the network encrypted content is decrypted using a secure processing device and/or secure processor. In such embodiments, the network encrypted content may be provided to the secure processing device and/or secure processor at operation 404. In one embodiment, the network encrypted content may be provided to the secure processor for decryption as it is received over a network. In another embodiment, the network encrypted content may be buffered prior to decryption by the secure processor.
As previously described, the secure processing device and/or secure processor may be part of the device performing the method 400 or may be a removable component of the device performing the method 400 (e.g., a smart card). In embodiments where the secure processor and/or secure processing device is a removable component, the secure processor and/or secure processing device may have a form factor such that it is compatible with legacy systems. For example, a smart card may have the form factor to operate in an ISO-7816 mode (or any other type of mode) in addition to a mode that supports the systems and methods for performing Transport I/O disclosed herein.
In one embodiment, the network encrypted content may be provided to the secure processor in an unfiltered manner. For example, one or more unfiltered MPEG Transport Streams may be provided. In such embodiments, the MPEG Transport Streams may be provided as received, without the prior removal of packets identified by packet identifiers (PIDs). In another embodiment, the device may filter the network encrypted content before decrypting the network encrypted content using a secure processor. For example, one or more filtered MPEG Transport Streams may be provided to the secure processor for decryption by removing some packets identified by PIDs. In yet another embodiment, multiple streams may be multiplexed and provided to the secure processor for decryption. For example, two or more MPEG Transport Streams may be multiplexed to create a combined stream. The combined stream may be provided to the secure processor for decryption.
In embodiments, the decryption operation 404 may also perform the method 200 discussed with respect to FIG. 2. In such embodiments, the result of the operation 404 may also yield locally encrypted content. Flow continues to operation 406 where the locally encrypted content is decrypted. In embodiments, the method 300 described with respect to FIG. 3 may be employed at operation 406 to decrypt the locally encrypted content. In embodiments, decryption of the locally encrypted content is performed by a component on the device performing the method 400 that is not part of the secure processor. For example, the decryption may be performed by a general processor. In embodiments, decrypting locally encrypted content may yield a stream of unencrypted content.
Flow continues to operation 408 where the clear content is processed. In one embodiment, clear content may be processed by providing the content to a display and/or audio device that is part of or connected to the device performing the method 400. In another embodiment, the clear content may be stored in memory or non-volatile storage at operation 408. One of skill in the art will appreciate that any type of processing of the clear content may be performed at operation 408.
As described with respect to embodiments of the method 400 a device performing the method may include different components to perform the different operations of the method 400. For example, decryption of the network encrypted content may be performed by a secure component that is part of the device. In embodiments, the secure component may be removable, such as a smart card. The local decryption and processing operations may be performed by components other than the secure component. However, because the decryption of the network encrypted content is performed by the secure component, the network control word is not vulnerable to interception and sharing. Thus, the method 400 is a more secure process of decrypting network encrypted content without exposing the one or more keys required to decrypt the network encrypted content.
In embodiments where the secure processor is removable, such as, but not limited to, a smart card, different data rates may be employed when the device performing the method 400 communicates with the removable secure processor. In one embodiment, a fixed data rate may be used for all communications between the device and the removable secure processor. In another embodiment, the data rate may be variable dependent upon the type of content and/or the type of messages exchanged between the device and the removable secure processor. In further embodiments, different types of signaling may be employed to communicate between the device and the removable secure processor. For example, in embodiments where the removable secure processor is a smart card, low-voltage differential signaling (LVDS) may be employed.
In further embodiments, the method 400 may be performed simultaneously on different network content to process multiple network encrypted streams or multiple pieces of network encrypted content. For example, in a set-top-box environment, the device may be able to process multiple data streams at a time. For example, a set-top-box may allow a user to watch one channel while recording one or more other channels. In such embodiments, the set-top-box may simultaneously employ the method 400 on multiple streams to decrypt the network encrypted content. In such embodiments, the removable secure processor, e.g., smart card, is capable of simultaneously decrypting multiple network encrypted content streams and creating multiple different locally encrypted streams. In such embodiments, different network control words may be used to decrypt the different network encrypted content and different local control words may be used to create different locally encrypted content.
FIG. 5 is an embodiment of a method 500 that may be employed to reset functionality of a secure device, such as, for example, a smart card, while maintaining transport stream functionality. Flow begins at operation 502 where the secure device receives an instruction to reset. In embodiments, the instruction may indicate that core functionality are to be reset independently from transport functionality. For example, core functionality may relate to the operating instructions, e.g., the core software, for the operating of the secure device. For example, the core software may be reset to, e.g., perform a software upgrade, to recover from a malfunction, or due to a lack of synchronization, etc. However, because the secure device processes network encrypted streams, unlike prior solutions where network encrypted streams were processed by components that were not part of the secure device, the secure device must be reset without interrupting streamed data. In the embodiments described herein, if the secure device is completely reset, the processing of the streamed data may be interrupted during the reset. In embodiments, the signal received at operation 502 may indicate a partial reset (e.g., resetting only core functionality and/or software) or the secure device may make a determination to perform a partial reset.
Flow continues to operation 504 where the secure device resets the core functionality while maintaining the transport functionality. In embodiments, the components of the secure device that perform the core functionality may be reset while the components that perform the transport functionality continue to operate. As such, maintenance may be performed on the core functionality of the secure device without interrupting the processing of data streams received by the secure device. For example, while the core functionality of the secure device are reset, the secure device may still able to receive transport data, process the transport data (e.g., by performing the method 200 from FIG. 2), and provide the processed packets (e.g., locally encrypted content) to another device. By performing the partial reset, network encrypted content may still be decrypted and locally encrypted during a reset of the device, thereby providing the ability of the secure device to continually provide content while performing maintenance. Flow then continues to operation 506 where the core functionality of the secure device are restarted and the maintenance is completed.
In embodiments, because the secure device is processing network data, e.g., the network encrypted content, variable bandwidth data is provided to the secure device. This differs from prior systems in which a secure device, e.g., a smart card, received a fixed bandwidth amount of data. In order to deal with variable bandwidth data, embodiments of the secure devices disclosed herein may perform a packet pacing algorithm. FIG. 6 is an embodiment of a packet pacing method 600 that may be employed by a secure device operating in a variable bandwidth environment. In embodiments, the method 600 is a closed loop feedback mechanism whereby a secure device may provide a clear to send (CTS) message or signal to notify that the device communicating with the secure device, e.g., a set-top-box or system on a chip, is allowed to send additional packets of data to the secure device. In embodiments, the method 600 may be employed to ensure that the secure device is capable of extracting a variable amount of data from multiple fixed input streams while throttling the amount of effective data by employing one or more CTS messages. In embodiments, sending a CTS message or signal by the secure device to a device it is communicating with triggers the device to send packets of interest (e.g., packets containing useful data such as transmission data, control data, etc.). In an embodiment, when the secure device does not send a CTS message, the secure device may receive stuffing packets from the device it is communicating with.
In embodiments, the secure device may employ a first-in-first-out (FIFO) buffer to perform packet pacing. The secure device may monitor the FIFO buffer to control the packet pacing of the variable bandwidth data received by the secure device. For example, the secure device may monitor the capacity and/or fullness of the FIFO buffer. If the number of packets queued in the FIFO fall below a threshold, the secure device may send a CTS message to a device communicating with the secure device to trigger receipt of additional data. In embodiments, a low level of data may be maintained in the FIFO buffer to ensure minimal latency for queued live packets that have a high priority. During periods of high activity, the secure device may ensure that live packets get higher priority by maintaining a small FIFO buffer.
Flow begins at operation 602 where the FIFO buffer is monitored. Monitoring the FIFO buffer may comprise checking the number of items in the FIFO buffer. In embodiments, any method of monitoring a buffer or the contents of a buffer may be performed at operation 602. Flow continues to decision operation 604, where a determination is made as to whether the number of contents in the FIFO buffer is lower than a predetermined threshold. In one embodiment, the threshold may be based upon processing time for a packet in the buffer. In another embodiment, the threshold may be based upon a calculation. If the number of items in the FIFO buffer is lower than the threshold, FIG. 6 shows that flow branches “YES” to operation 606 where a CTS message or signal is sent to trigger the receipt of additional data packets and flow returns to operation 602. For example, the CTS message may be sent to a video processing device, a set-top-box, or other type of device instructing the device to send additional data to the secure processor. If the number of items is not lower than the threshold, FIG. 6 shows that flow branches “NO” and returns to operation 602. Although embodiments have been described with a FIFO buffer, other types of queues may be employed without departing from the scope of the present disclosure.
In embodiments where the secure processor is a removable component, the secure processor may be designed such that it is capable of working in legacy systems. In embodiments, the secure processor is a removable component that has a legacy form factor. For example, a smart card may be designed to support both ISO-7816 signals and signals for the Transport I/O system described herein. FIG. 7 is an embodiment illustrating the compatibility between an ISO-7816 smart card and a smart card capable of supporting the systems and methods disclosed herein. Smart card 702 is an embodiment of an ISO-7816 compatible smart card. Smart card 704 is a smart card compatible with both ISO-7816 and the Transport I/O systems and methods disclosed herein. In the illustrated embodiment, smart card 704 includes all of the contacts necessary to be compatible with the ISO-7816 standard (e.g., supports a legacy form factor). Additionally, smart card 704 includes six contacts, identified by the ellipse 706 that may be used to perform the systems and methods described herein. In such embodiments, the smart card 704 may be capable of working with both existing systems (e.g., legacy devices deployed to the field) and Transport I/O capable systems.
In embodiments, the device performing the method 400 and/or the removable secure device may make a determination as to whether to operate in a legacy mode (e.g., an ISO-7816 mode) or in a Transport I/O system compatible mode at start up. In one embodiment, the determination may be made based upon a signal sent to the removable secure device at initialization. Further details regarding the making of such determination is provided in U.S. patent application Ser. No. 13/184,831 entitled, “Multiple-Speed Interface,” filed on Jul. 18, 2011, which claims priority to U.S. Provisional Patent Application No. 61/364,854, filed on Jul. 16, 2011, which is hereby incorporated by reference in its entirety.
FIG. 8 is an embodiment of a secure processing device 800 that may be employed with the systems or to perform the methods disclosed herein. In embodiments, the secure processing device may be a smart card. However, one of skill in the art will appreciate that any other type of secure device may be employed with the systems and methods disclosed herein. In embodiments, the secure processing device may be part of a device performing the method 400 described with respect to FIG. 4. In another embodiment, the secure processing device 600 may be a removable component of a device performing the method 400.
In embodiments, secure processing device 800 includes one or more processing units 802. In some embodiments, one or more components of the methods described herein are performed by the one or more processing units 802. For example, the one or more processing units 802 may be used to decrypt network encrypted content, create locally encrypted content, and create non-content data as described in the method 200 of FIG. 2.
Secure processing device 800 may also include memory 804. Memory 604 includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, or any other tangible medium which is used to store information and which is accessed by secure processing device 800 and one or more processing units 802. Memory 804 may store executable instructions to perform the methods disclosed herein. For example, memory 804 may include instructions to decrypt network encrypted content (NEC) 806. Memory may also store the instructions to encrypt clear content to create locally encrypted content (LEC) 808.
Secure processing device 800 may also contain communications connection(s) 810 that allow the device to communicate with other devices. Communication connection(s) 810 is an example of communication media. Communication media may embody a modulated data signal, such as a carrier wave or other transport mechanism and includes any information delivery media, which may embody computer readable instructions, data structures, program modules, or other data in a modulated data signal. The term “modulated data signal” means a signal that has one or more of its characteristics set or changed in such a manner as to encode information or a message in the data signal. By way of example, and not limitation, communication media includes wired media such as a wired network or direct-wired connection, and wireless media such as an acoustic, RF, infrared, and other wireless media. In embodiments, network encrypted content such may be received over communications connection(s) 810. Locally encrypted content may be transmitted over communications connection(s) 810. In still further embodiments, the instructions to perform the Transport I/O methods described herein may be received via communications connection(s) 810. For example, a head-end may update secure processing device 800 with instructions to perform the methods disclosed herein. The instructions may be stored in memory 804. Communications connection(s) 810 thereby allows a head-end to update smart cards deployed in the field with instructions to perform the methods herein. Communications connections also provide the secure processing device 800 with the ability to receive network encrypted content from a device and return locally encrypted content to the device. In embodiments, communication connections may be pads on a smart card, such as, but not limited to, the pads identified as Transport I/O capable pads 706 in FIG. 7.
Although the embodiment of the secure processing device 800 is illustrated as having memory 804 that includes instructions to perform the methods disclosed herein, in alternate embodiments, the instructions to perform the methods disclosed herein may be performed by an application specific integrated circuit (ASIC) that is part of the secure processing device 800.
FIG. 9 is an embodiment of a set-top-box that may be used to perform the Transport I/O system methods and be part of the systems disclosed herein. In another embodiment, different recipient devices such as, but not limited to, a smart phone, a tablet computer, a laptop, or any other type of device may be employed containing some of the components illustrated in FIG. 9. While FIG. 9 is illustrated with various components, many of the components are known to the art and do not need explanation. Only the components that may be used to perform the methods disclosed herein are described. The signal 904 that arrives at the set-top-box 900 may undergo extensive processing. The television converter 900 may include one or more tuner devices 906, 946, 948 that may receive a signal 904. Signal 904 may be a satellite signal, a cable signal, or any other type of signal received over a wired or wireless network. In this embodiment, tuner devices 906, 946, 948 acquire a signal 904 from a head-end or content provider. Tuner devices 906, 946, 948 may initially process the signal 904. Signal 904 may be a data stream that comprises network encrypted content (e.g., one or more multiple network encrypted streams), multiple clear content (e.g., one or more multiple clear content streams) and/or metadata containing information about the data stream or the multiple encrypted and/or clear streams that make up the data stream. Tuner device 906, 946, 948 may also receive subscriber commands in the form of signals from control electronics unit 902. Signals from control electronics unit 902 may include, but is not limited to, a signal to tune to a transponder as part of the process of selecting a certain channel for viewing on a peripheral device. One skilled in the art would recognize that the tuner devices 906, 946, 948 may include fewer, more, or different components. The signal 904 may include content encoded by a network control word. The signal 904 may also include one or more ECMs and EMMs.
After receiving the signal 904, one of the first steps may be to demodulate 908 the signal 904. The signal 904 may arrive as an analog signal that “carries” data (e.g., data is modulated onto the analog signal). Demodulation 908 may be accomplished by reversing the modulation process. Modulation can be done in several ways. Modulation may include amplitude modulation (AM) or frequency modulation (FM). If the carried data is digital, modulation methods include, but are not limited to, biphase-shift keying (BPSK), quadraphase-shift keying (QPSK), or eight-phase shift keying (8PSK). One skilled in the art will recognize that other methods of modulating and demodulating the signal 904 may be possible. Another one of the first steps may also be to error correct 908 signal 904. One example of error correcting 908 is forward error correction (FEC). FEC 908 may include, but is not limited to, inspecting parity bit or bits that may accompany signal 904. One skilled in the art will recognize that many methods for error correcting are possible. For the purposes of discussion, an embodiment using digital data will be discussed below. However, one skilled in the art will recognize that systems with analog data or combined analog and digital data are also possible and contemplated herein.
In embodiments, set-top-box 900 contains control electronics unit 902 that receives signal 904. In embodiments, the control electronics unit 902 may comprise a smart card interface. One skilled in the art will recognize that control electronics 902 may receive other signals, including, but not limited to, signals from a cable, satellite, or broadcast television distributor. In this embodiment, control electronics unit 902 includes discrete electronic components combined into a single circuit with a shared bus 910. In other embodiments, control electronics unit 902 may be configured differently. For example, one or more of the control electronics unit 902 components in set-top-box 900 may be combined or omitted. As a further example, one or more of the control electronics unit 902 components in set-top-box 900 may not share a bus 910, but may nonetheless be operatively connected by some other means. One skilled in the art will recognize that other configurations of set-top-box 900 and control electronics unit 902 are possible and within the scope of this invention. One skilled in the art will further recognize that some components of set-top-box 900 and control electronics unit 902 may be implemented in hardware or software. The control electronics unit 902 may operate under the control of a software program, firmware program, or some other program stored in memory or control logic. One skilled in the art will also recognize that the control electronics unit 902 may include other electronic components or structures to mediate or process signals.
Control electronics unit 902 may contain one or more central-processing-units (CPUs) 912 or processors. In this embodiment, control electronics unit 902 contains a single CPU 912 that is operatively connected to the shared bus. In this embodiment, CPU 912 may be used, among other things, for logical operations for set-top-box 900 functions including, but not limited to, channel selection, recording control, EPG display and control and system maintenance. One skilled in the art will recognize that the CPU 912 may be integrated with memory or other discrete electronics components. In embodiments, CPU 912 may be used to perform the systems and methods disclosed herein. For example, CPU 912 may be used to perform a method of decrypting locally encrypted content as described with respect to FIG. 3. However, in embodiments, local decryption may be performed by other components, such as a dedicated crypto engine (not shown). One of skill in the art will appreciate that although specific components are described with respect to FIG. 9, the system and methods disclosed herein may be performed by other components or other types of devices without departing from the spirit of this disclosure.
Control electronics unit 902 may contain one or more volatile memory components 914. Volatile memory components 914 may include, but are not limited to, one or more SDRAM memory chips. Similarly, control electronics unit 902 may also contain one or more non-volatile memory components 916. Non-volatile memory 916 may include one or more memory chips, including, but not limited to, ROM, EEPROM, and Flash. One skilled in the art will recognize that volatile memory 914 and non-volatile memory 916 may be integrated within other electronics components. One skilled in the art will also recognize that other memory components may be included within set-top-box 900 and control electronics unit 902. One skilled in the art will recognize that memory 914, 916 may be used for many purposes, including, but not limited to, storing EPG data and storing data for use by CPU 912. In embodiments, the Volatile memory components 914 and/or one or more non-volatile memory components 916 may be used to store the instructions to perform methods 300 and 400 disclosed herein. Non-volatile memory 916 may be used to store locally encrypted content or clear content. In other embodiments, hard drive 950 may be used to store locally encrypted content or clear content.
A set-top-box 900 may be connected to one or more peripheral electronic devices through peripheral interface 924. These peripheral devices may include a smart card 936. In embodiments, the smart card 936 acts as a conditional access system. In such embodiments, the smart card 936 performs the methods 200 and 400 disclosed herein. In embodiments, smart card 936 may be a smart card such as smart card 504 that is capable of supporting both a legacy mode of operation and a Transport I/O mode of operation. In still further embodiments, smart card 936 may have the components described with respect to FIG. 8. Peripheral interface 924 may also act as an I/O connection to provide the clear content to a display device, such as, but not limited to, a television and speakers.
With reference to FIG. 10, an embodiment of a computing environment for implementing the various embodiments described herein includes a computer system, such as computer system 1000. Any and all components of the described embodiments (such as the DVR, the content storage sever, a laptop, mobile device, personal computer, a smart phone, a secure processing device, etc.). may execute as or on a client computer system, a server computer system, a combination of client and server computer systems, a handheld device, and other possible computing environments or systems described herein. As such, a basic computer system applicable to all these environments is described hereinafter.
In its most basic configuration, computer system 1000 comprises at least one processing unit or processor 1004 and system memory 1006. The most basic configuration of the computer system 1000 is illustrated in FIG. 10 by dashed line 1002. In some embodiments, one or more components of the described system are loaded into system memory 1006 and executed by the processing unit 1004 from system memory 1006. Depending on the exact configuration and type of computer system 1000, system memory 1006 may be volatile (such as RAM), non-volatile (such as ROM, flash memory, etc.), or some combination of the two.
Additionally, computer system 1000 may also have additional features/functionality. For example, computer system 1000 may include additional storage media 1008, such as removable and/or non-removable storage, including, but not limited to, magnetic or optical disks or tape or solid state storage. In some embodiments, software or executable code and any data used for the described system is permanently stored in storage media 1008. Storage media 1008 includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules, or other data.
System memory 1006 and storage media 1008 are examples of computer storage media. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage, other magnetic storage devices, solid state storage or any other tangible medium which is used to store the desired information and which is accessed by computer system 1000 and processor 1004. Any such computer storage media may be part of computer system 1000. In some embodiments, system memory 1006 and/or storage media 1008 may store data used to perform the methods or form the system(s) disclosed herein. In other embodiments, system memory 1006 may store information such as the local control word 1014 and logic 1016 to perform the methods of decrypting locally encrypted content as described herein.
Computer system 1000 may also contain communications connection(s) 1010 that allow the device to communicate with other devices. Communication connection(s) 1010 is an example of communication media. Communication media may embody a modulated data signal, such as a carrier wave or other transport mechanism and includes any information delivery media, which may embody computer readable instructions, data structures, program modules, or other data in a modulated data signal. The term “modulated data signal” means a signal that has one or more of its characteristics set or changed in such a manner as to encode information or a message in the data signal. By way of example, and not limitation, communication media includes wired media such as a wired network or direct-wired connection, and wireless media such as an acoustic, RF, infrared, and other wireless media. In an embodiment, content and metadata may be transmitted over communications connection(s) 1010.
In some embodiments, computer system 1000 also includes input and output connections 1012, and interfaces and peripheral devices, such as a graphical user interface. Input device(s) are also referred to as user interface selection devices and include, but are not limited to, a keyboard, a mouse, a pen, a voice input device, a touch input device, etc. Output device(s) are also referred to as displays and include, but are not limited to, cathode ray tube displays, plasma screen displays, liquid crystal screen displays, speakers, printers, etc. These devices, either individually or in combination, connected to input and output connections 1012 are used to display the information as described herein. All these devices are well known in the art and need not be discussed at length here. In further embodiments, the input and output connections 1012 may be used to communicate with a removable secure processor, such as, but not limited to, a smart card.
In further embodiments, computer system 1000 may include a secure processor 1018 and secure memory 1020 that may be used to perform some of the methods disclosed herein. In embodiments, the secure processor 1018 and secure memory 1020 of the computer system 1000 may comprise a secure area 1022 that is not generally accessible by the other components of computer system 1000 or by other processes executing on the computer system 1000. In embodiments, secure memory may store instructions to decrypt network encrypted content and create locally encrypted content as described with respect to FIG. 2. Such instructions may be executed by the secure processor 1018. In such embodiments, network control words may remain within the secure area 1022, thereby reducing the chance of interception and sharing by unauthorized parties.
In some embodiments, the components described herein comprise such modules or instructions executable by computer system 1000 that may be stored on computer storage medium and other tangible mediums and transmitted in communication media. Computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules, or other data. Combinations of any of the above should also be included within the scope of readable media. In some embodiments, computer system 1000 is part of a network that stores data in remote storage media for use by the computer system 1000.
The embodiments described herein may be employed using software, hardware, or a combination of software and hardware to implement and perform the systems and methods disclosed herein. Although specific devices have been recited throughout the disclosure as performing specific functions, one of skill in the art will appreciate that these devices are provided for illustrative purposes, and other devices may be employed to perform the functionality disclosed herein without departing from the scope of the disclosure.
This disclosure described some embodiments of the present invention with reference to the accompanying drawings, in which only some of the possible embodiments were shown. Other aspects may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments were provided so that this disclosure was thorough and complete and fully conveyed the scope of the possible embodiments to those skilled in the art.
Although specific embodiments were described herein, the scope of the invention is not limited to those specific embodiments. One skilled in the art will recognize other embodiments or improvements that are within the scope and spirit of the present invention. Therefore, the specific structure, acts, or media are disclosed only as illustrative embodiments. The scope of the invention is defined by the following claims and any equivalents therein.

## Claims

1. A removable security device comprising:
at least one processor; and
memory encoding computer executable instructions that, when executed by the at least one processor, performs a method comprising:
receiving a signal during initialization;
based upon the signal, determining whether the removable security device is operating in a legacy mode;
when the removable security device is not operating in the legacy mode, performing, by the removable security device, operations comprising:
receiving, from a head-end, at least one network control word;
maintaining the at least one network control word on the removable security device such that the at least one network control word is not transmitted from the removable security device;
receiving a first network encrypted elementary stream;
receiving a second network encrypted elementary stream;
decrypting the first and second network encrypted elementary streams using the at least one network control word to generate first and second clear content streams;
obtaining at least one local control word, wherein the at least one local control word is generated by the removable security device;
encrypting the first and second clear content streams by the removable device to produce first and second locally encrypted content streams, wherein the first and second locally encrypted content streams are produced using the at least one local control word;
multiplexing the first and second locally encrypted content streams to produce an output stream; and
providing the output stream to a video processing device.

2. The removable security device of claim 1, wherein the removable security device is a smart card in a set-top-box.

3. The removable security device of claim 1, wherein the removable security device supports a legacy form factor.

4. The removable security device of claim 3, wherein the legacy form factor is compatible with the ISO-7816 standard.

5. The removable security device of claim 1, wherein encrypting the first and second clear content streams utilizes a transport mode encryption.

6. The removable security device of claim 1, wherein encrypting the first and second clear content streams utilizes a bulk mode encryption.

7. The removable security device of claim 1, wherein the removable security device and the video processing device communicate using LVDS signaling.

8. The removable security device of claim 1, wherein a first network control word is used to decrypt the first network encrypted elementary stream and second network control word is used to decrypt the second network encrypted elementary stream, and wherein the first and second network control words are different.

9. The removable security device of claim 1, wherein the at least one local control word is generated by the removable security device.

10. The removable security device of claim 1, wherein the local control word is obtained from a key ladder.

11. The removable security device of claim 1, wherein the operations further comprise:
receiving at least one additional network encrypted elementary stream;
decrypting the at least one additional network encrypted elementary stream using at least one additional network control word to generate at least one additional clear content stream;
encrypting the at least one additional clear content stream to produce at least one additional locally encrypted content stream; and
wherein multiplexing further comprises multiplexing the first, second, and at least one additional locally encrypted content stream into the output stream.

12. The removable security device of claim 1, wherein the operations further comprise:
obtaining a first local control word, wherein the first clear content stream is encrypted using the first local control word; and
obtaining optional additional local control word(s), wherein the optional additional network content stream(s) are encrypted using the optional additional local control word(s), and wherein some or all of the local control words are different.

13. A method comprising:
receiving a signal during initialization;
based upon the signal, determining whether the removable security device is operating in a legacy mode;
when the removable security device is not operating in the legacy mode, performing, by the removable security device, operations comprising:
receiving, from a head-end, at least one network control word;
maintaining the at least one network control word on the removable security device such that the at least one network control word is not transmitted from the removable security device;
receiving a first network encrypted elementary stream;
receiving a second network encrypted elementary stream;
decrypting the first and second network encrypted elementary streams using the at least one network control word to generate first and second clear content streams;
obtaining at least one local control word, wherein the at least one local control word is generated by the removable security device;
encrypting the first and second clear content streams by the removable device to produce first and second locally encrypted content streams, wherein the first and second locally encrypted content streams are produced using the at least one local control word;
multiplexing the first and second locally encrypted content streams to produce an output stream; and
providing the output stream to a video processing device.

14. The method of claim 13, wherein the removable security device is a smart card.

15. The method of claim 13, wherein encrypting the first and second clear content streams utilizes a transport mode encryption.

16. The method of claim 13, wherein encrypting the first and second clear content streams utilizes a bulk mode encryption.

17. The method of claim 13, wherein the removable security device and the video processing device communicate using LVDS signaling.

18. The method of claim 13, further comprising:
receiving at least one additional network encrypted elementary stream;
decrypting the at least one additional network encrypted elementary stream using at least one additional network control word to generate at least one additional clear content stream;
encrypting the at least one additional clear content stream to produce at least one additional locally encrypted content stream; and
wherein multiplexing further comprises multiplexing the first, second, and at least one additional locally encrypted content stream into the output stream.

19. The method of claim 13, wherein the operations further comprising:
obtaining a first local control word, wherein the first clear content stream is encrypted using the first local control word; and
obtaining optional additional local control word(s), wherein the optional additional network content stream(s) are encrypted using the optional additional local control word(s), and wherein some or all of the local control words are different.

20. A system comprising:
a set-top-box; and
a smart card connected to the set-top-box, the smart card performing a method comprising:
receiving, at the smart card, a signal from the set-top-box during initialization;
based upon the signal, determining whether the smart card is operating in a legacy mode;
when the smart card is not operating in the legacy mode, performing, by the smart card, operations comprising:
receiving, from a head-end, at least one network control word;
maintaining the at least one network control word on the smart card such that the at least one network control word is not transmitted from the smart card;
receiving a first network encrypted elementary stream;
receiving a second network encrypted elementary stream;
decrypting the first and second network encrypted elementary streams using the at least one network control word to generate first and second clear content streams;
obtaining at least one local control word, wherein the at least one local control word is generated by the smart card;
encrypting the first and second clear content streams by the removable device to produce first and second locally encrypted content streams, wherein the first and second locally encrypted content streams are produced using the at least one local control word;
multiplexing the first and second locally encrypted content streams to produce an output stream; and
providing the output stream to a video processing device.

21. The system of claim 20, wherein the operations further comprise:
receiving at least one additional network encrypted elementary stream;
decrypting the at least one additional network encrypted elementary stream using at least one additional network control word to generate at least one additional clear content stream;
encrypting the at least one additional clear content stream to produce at least one additional locally encrypted content stream; and
wherein multiplexing further comprises multiplexing the first, second, and at least one additional locally encrypted content stream into the output stream.

22. The system of claim 20, wherein the operations further comprise:
obtaining a first local control word, wherein the first clear content stream is encrypted using the first local control word; and
obtaining optional additional local control word(s), wherein the optional additional network content stream(s) are encrypted using the optional additional local control word(s), and wherein some or all of the local control words are different.

23. The system of claim 20, wherein the smart card and the set-top-box communicate using LVDS signaling.