WO2001074075A1

WO2001074075A1 - Removable smart card interface for set top box

Info

Publication number: WO2001074075A1
Application number: PCT/US2001/009674
Authority: WO
Inventors: Jun Maruo; Atsushi Kagami
Original assignee: Sony Electronics, Inc.
Priority date: 2000-03-29
Filing date: 2001-03-26
Publication date: 2001-10-04
Also published as: AU2001251008A1

Abstract

A system and method thereof for using a portable conditional access block (e.g. removable smart card interface) in an intelligent transceiver (e.g. a set-top box). The intelligent transceiver is adapted to receive different types of removable smart card interfaces (320) particular to the different content providers (e.g. digital broadcast system operators). A smart card (325) provided by the digital broadcast system operator is inserted into the removable smart card interface (320). A scramble key provided by the digital broadcast system operator is used with the smart card to execute a scheme for descrambling scrambled audio and video digital signals received by the intelligent transceiver. The removable smart card interface permits ready interchangeability of the conditional access block depending on the descrambling scheme of the broadcast system operator. Thus, the same intelligent transceiver design can be used with different broadcast system operators.

Description

REMOVABLE SMART CARD INTERFACE FOR SET TOP BOX

BACKGROUND

FIELD

The present disclosure relates to the field of intelligent transceivers such as bi-directional set-top boxes. The disclosure pertains to a modular conditional access block. More specifically, the present disclosure pertains to an intelligent transceiver design that uses a portable conditional access block (a removable smart card interface) in order to accommodate the different smart cards and different descrambling schemes used by various broadcast system operators.

BACKGROUND ART

Digital broadcast systems include direct broadcast digital satellite systems, interactive World Wide Web ("Web") access systems, and digital cable systems. Digital broadcasting provides a number of advantages to subscribers, such as variety and flexibility of programming, useful and comprehensive support services (such as detailed electronic programming guides), and superior audio and video quality.

The Conditional Access (CA) function of a digital broadcast system allows selective access, for a fee, to premium services such as pay-per-view movies and events. The producers of the movies, events, etc., require that access to the premium services be controlled in order to protect their commercial interests as well as to enforce copyrights and protect copyright ownership. The digital broadcast system operators (also referred to as Multiple System Operators, MSOs) also have a commercial interest in limiting access to these premium services to authorized users only. Subscribers receive digital broadcasts (including satellite, cable and Web broadcasts) via set-top boxes or other similar consumer electronic equipment located in the subscriber's home. With a bi-directional set-top box, in addition to receiving broadcasts, a subscriber can transmit messages to the MSO. Using the bi-directional set-top box (generally, a "transceiver" or "intelligent transceiver"), the subscriber selects a premium service, and the subscriber's selection.as well as information needed for billing purposes is transmitted to the MSO.-

Typically, the signal carrying the premium service, or the audio and video content within the signal, is scrambled to prevent unauthorized access and use. The signal is descrambled in the transceiver using a scrambling scheme that is enabled and executed using a "scramble key" and "smart card" provided by the MSO. The smart card also stores the information needed for billing, and on a periodic basis (perhaps once per month) an automatic connection is made between the transceiver and the MSO so that the billing information can be transmitted to the MSO.

Prior Art Figure 1 A is an illustration of an exemplary prior art transceiver 110. Smart card 25 is inserted into a conditional access block (also referred to as a point of deployment, not shown) which is built into transceiver 110. Digital broadcast signal 70 is received by transceiver 110 and forwarded to the conditional access block, where it is descrambled using the scramble key in combination with smart card 25. Once descrambled and therefore in the clear, the digital signal may be encrypted to prevent it from being pirated. Subsequently, the digital signal is decrypted, the audio and video content are decoded and processed, and the result (output 80) is sent to, for example, a television (not shown) or similar display device.

Prior Art Figure 1 B is a block diagram of intelligent transceiver 110 of Prior Art Figure 1 A. Transceiver 110 receives a digital broadcast signal 70 from a digital broadcaster or content provider (e.g., an MSO). Bus 5 is an internal bus for communicating electronic information between the functional blocks of transceiver 110. Front-end block 10 contains at least one tuner for receiving digital broadcast signal_70. Central processing unit 60 contains a processor and memory for executing and storing instructions. Smart card 25 is used with the scramble key to descramble digital broadcast signal 70. Smart card 25 is inserted into conditional access block 30 (or point of deployment, POD), which contains the descrambling scheme used to descramble digital broadcast signal 70. Typically, conditional access block 30 also contains an encryption engine that is used to encrypt the descrambled signal. A/V (audio/video) decode block 40 decrypts an encrypted signal and decodes the audio and video content provided in the signal (e.g., using AC3 Digital Dolby and/or Moving Pictures Experts Group decoding). Graphics block 50 processes the audio and video information and provides the output to, for example, a display device (not shown).

A problem with the prior art occurs because different MSOs can use different scrambling/descrambling schemes. Thus, although the primary functions of the transceiver (e.g., descrambling, decoding, etc.) may be essentially the same for each MSO, a transceiver designed for one MSO may have to be different than a transceiver designed for another MSO because of a difference in the scrambling/descrambling schemes used by each. Similarly, a problem with the prior art can also occur because different MSOs can use different types of smart cards. Thus, as above, a transceiver designed for one MSO may have to be different than a transceiver designed for another MSO in order to accommodate different smart cards.

Therefore, a problem in the prior art is that current transceiver designs offer little flexibility with regard to allowing a transceiver designed for one market or MSO to be readily adapted for use in another market or with another MSO. Thus, manufacturers of these transceivers at great cost generally must design and manufacture several different types of customized transceivers. As a result, manufacturers face increased development and fabrication costs, and these costs are typically passed to the consumer. Clearly, for the benefit of the manufacturer as well as the consumer, it is desirable to minimize these costs.

SUMMARY

Accordingly, what is needed is an apparatus and/or method that can allow greater flexibility with regard to the design of transceivers (e.g., a set-top boxes) for different markets and for different digital broadcast system operators, thereby reducing costs to manufacturers and consumers.

The present invention includes an apparatus and method thereof that satisfy the above needs. These and other advantages of the present invention not specifically mentioned above will become clear within discussions of the present invention presented herein.

The present invention pertains to system and method thereof for using a portable conditional access block (e.g., a removable smart card interface) in an intelligent transceiver (e.g., an intelligent set-top box). The intelligent transceiver includes an in-band tuner for receiving in-band digital signals containing scrambled audio and video content. In accordance with the present invention, the intelligent transceiver is adapted to receive different ^"types of removable smart card interfaces particular to the different content providers (e.g., digital broadcast system operators or Multiple System Operators). A subscriber to a particular digital broadcast system couples the removable smart card interface appropriate for that system to the intelligent transceiver. A smart card provided by the digital broadcast system operator is inserted into the removable smart card interface. A scramble key provided by the digital broadcast system operator is used with the smart card to execute a scheme for descrambling the scrambled audio and video content. In one embodiment, after descrambling, the resultant digital signals are encrypted.

In one embodiment, the intelligent transceiver incorporates an out-of- band tuner that receives out-of-band digital signals that include the scramble key used by the descrambling scheme. In another embodiment, the intelligent transceiver incorporates a tuner that receives, via the Internet, digital signals that include the scramble key.

In one embodiment, a descrambler unit and an encryption unit are included in a functional block in the intelligent transceiver. In another embodiment, a descrambler unit and an encryption unit are included in the removable smart card interface.

The removable smart card interface permits ready interchangeability of the conditional access functions depending on the type of descrambling scheme and smart card used by the broadcast system operator, thus, the same intelligent transceiver design can be used with different broadcast system operators, thereby reducing manufacturing costs and consequently reducing the cost to consumers. BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention:

PRIOR ART FIGURE 1A is a perspective illustration of an exemplary embodiment of a prior art intelligent transceiver.

PRIOR ART FIGURE 1 B is a block diagram of an exemplary embodiment of a prior art intelligent transceiver.

FIGURE 2A is a block diagram of one embodiment of an intelligent transceiver upon which embodiments of the present invention may be practiced.

FIGURE 2B is a block diagram of another embodiment of an intelligent transceiver upon which embodiments of the present invention may be practiced.

FIGURE 3 is a block diagram of one embodiment of an intelligent bidirectional transceiver in accordance with the present invention.

FIGURE 4 is a perspective illustration of one embodiment of an intelligent transceiver in accordance with the present invention.

FIGURE 5 is a block diagram of an exemplary digital broadcast system in accordance with one embodiment of the present invention. FIGURE 6 is an illustration of the frequencies associated with different types of broadcast digital signals in accordance with one embodiment of the present invention.

FIGURE 7 is a flowchart of the steps in a process for descrambling a digital signal in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION

In the following detailed description of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be recognized by one skilled in the art that the present invention may be practiced without these specific details or with equivalents thereof. In other instances, well known methods, procedures, components, and circuits have not been described in detail as not to unnecessarily obscure aspects of the present invention.

Some portions of the detailed descriptions which follow are presented in terms of procedures, logic blocks, processing, and other symbolic representations of operations on data bits within an intelligent electronic media device. These descriptions and representations are the means used by those skilled in the data processing arts to most effectively convey the substance of their work to others skilled in the art. A procedure, logic block, process, etc., is herein, and generally, conceived to be a self-consistent sequence of steps or instructions leading to a desired result. The steps are those requiring physical manipulations of physical quantities. Usually, though not necessarily, these physical manipulations take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated in a consumer electronic media device. For reasons of convenience, and with reference to common usage, these signals are referred to as bits, values, elements, symbols, characters, terms, numbers, or the like with reference to the present invention. It should be borne in mind, however, that all of these terms are to be interpreted as referencing physical manipulations and quantities and are merely convenient labels and are to be interpreted further in view of terms commonly used in the art. Unless specifically stated otherwise as apparent from the following discussions, it is understood that throughout discussions of the present invention, discussions utilizing terms such as "receiving" or "enabling" or "encrypting" or "descrambling" or the like, refer to the action and processes (e.g., process 700 of Figure 7) of an electronic device such as a microcontroller or similar electronic computing device (e.g., dedicated or embedded computer system) that manipulates and transforms data. The data are represented as physical (electronic) quantities within the electronic device's registers and memories and is transformed into other data similarly represented as physical quantities within the electronic device memories or registers or other such information storage, transmission, or display screens.

The present invention is described in the context of an intelligent transceiver (e.g., a set-top box) that can be used as part of a digital broadcast system. However, it is appreciated that the present invention may be utilized in other types of devices including consumer electronic devices where it may be necessary to descramble a digital signal.

Figure 2A is a block diagram of one embodiment of an intelligent transceiver 300 (e.g., a set-top box) in accordance with the present invention. Intelligent transceiver 300 receives digital broadcast signal 370 from a digital broadcaster (not shown). Digital broadcast signal 370 is a media signal comprising audio and video content. Digital broadcast signal 370 can be delivered to intelligent transceiver 300 using any of the various mechanisms currently in use or envisioned, such as a terrestrial line (e.g., a cable system), the World Wide Web (e.g., a connection to the Internet), or a wireless transmission (e.g., a satellite broadcast). In accordance with the present invention, a number of different digital broadcast signal formats in use or envisioned can be used, such as the Advanced Television Systems Committee (A SC) digital television format.

In the present embodiment, intelligent transceiver 300 includes front-end block 310 coupled to bus 305, conditional access block 330 coupled to front- end block 310 and bus 305, audio/video (A/V) decode block 340 coupled to conditional access block 330 and bus 305, graphics block 350 coupled to A/V decode block 340 and bus 305, and central processing unit 360 coupled to bus 305. Bus 305 is an internal address/data bus for communicating digital information between the functional blocks of intelligent transceiver 300. In one embodiment, bus 305 is a high bandwidth bus, for example a Peripheral Component Interconnect (PCI) bus, capable of communicating A/V data between the modularized blocks 310, 330, 340, 350 and 360. In the present embodiment, transceiver 300 utilizes a modular architecture, comprising different functional blocks, each dedicated to a specific function required to be performed by transceiver 300 (e.g., receiving and sending data signals, decrypting and decoding, and audio and visual processing). ln accordance with the present embodiment of the present invention, point of deployment (POD) 320 is separate from but connectable to intelligent transceiver 300, and smart card 325 is plugged into POD 320. Smart card 325 stores information needed by a cable system operator or digital broadcast system operator (e.g., a Multiple System Operator, MSO) in order to bill a subscriber for services used by the subscriber (for example, the viewing of a pay-per-view movie or event). Smart card 325 also receives a scramble key provfded by the MSO to descramble digital broadcast signal 370 (if the signal is scrambled).

In the present embodiment, POD 320 contains a descrambler unit (not shown) that descrambles digital broadcast signal 370 using the scramble key from smart card 325. POD 320 can also contain an encryption unit for encrypting digital broadcast signal 370 after it is descrambled. In one embodiment, the encryption unit uses a well-known DES ECB (Data Encryption Standard Electronic Code Book) encryption routine and a key length of 56 bits. However, it is appreciated that other well-known and commercially available encryption routines and different key lengths may be used in accordance with the present invention.

In an alternate embodiment, the descrambler unit and the encryption unit are located in intelligent transceiver 300, specifically in conditional access block 330. It is appreciated that, in the embodiment in which the descramble and encryption functions are performed by POD 320 instead of conditional access block 330, conditional access block 330 can still to be present in intelligent transceiver 300 without performing those functions. Alternatively, conditional access block 330 may not be included in intelligent transceiver 300; see Figure 2B.

In accordance with the present embodiment of the present invention, POD 320 can be inserted into and coupled with intelligent transceiver 300, as well as detached and removed from intelligent transceiver 300. Thus, POD 320 provides a removable and portable smart card interface with conditional access functions for intelligent transceiver 300. Intelligent transceiver 300 is adapted to receive different types of removable smart^' card interfaces particular to the different MSOs and markets, and therefore can be used with a multiplicity of different types of PODs and/or smart cards. Thus, in accordance with the present invention, intelligent transceiver permits ready interchangeability of POD 320 depending on the descrambling scheme and smart card used by the particular MSO. Accordingly, the same intelligent transceiver design can be used with different MSOs and markets, reducing manufacturing costs and thus reducing the cost to the consumer.

Continuing with reference to Figure 2A, in the present embodiment, front- end block 310 contains one or more tuners for receiving digital broadcast signal 370. For example, in one embodiment, front-end block 310 can contain an in- band tuner (not shown) for receiving in-band digital signals via wireless transmission (e.g., a satellite broadcast) and another tuner (not shown) for receiving a cable or Internet transmission via a cable modem. Front-end block 310 can also include a device (e.g., a modem) that allows a telephone or digital subscriber line (DSL) connection to be made to the World Wide Web so that a broadcast signal can be received via the Internet. In another embodiment, front- end block 310 includes an out-of-band tuner (not shown) for receiving out-of- band digital signals. In one embodiment, front-end block 310 contains substantially all of the devices needed for bi-directional communication; therefore, the devices needed by transceiver 300 for bi-directional communication are substantially located in a single functional block.

The in-band digital signals typically include scrambled audio and video content; see Figure 6. In one embodiment, the scramble key used to descramble the audio and video content is provided over the Internet via the cable modem and associated tuner. In another embodiment, the scramble key is provided in the out-of-band digital signals along with other service information; see Figure 6.

With reference to Figure 2A, in the present embodiment, central processing unit 360 contains a processor (not shown) for processing information and instructions. Central processing unit 360 also may contain random access memory, read only memory, one or more caches, a flash memory and the like (not shown) for storing information and instructions.

In the present embodiment, A/V decode block 340 is an integrated circuit device comprising a functional block and a decryption engine 345 integrated therein. Decryption engine 345 is integral with AA/ decode block 340 (that is, as a single integrated circuit, or "chip") and, in the present embodiment, is coupled to front-end block 310 via conditional access block 330. In the present embodiment, the link between conditional access block 330 and A/V decode block 340 (specifically, decryption engine 345) is separate from bus 305; that is, there is a direct connection between conditional access block 330 and decryption engine 345 that bypasses bus 305.

Decryption engine 345 decrypts an encrypted signal (e.g., digital broadcast signal 370) received by A V decode block 340. The output of decryption engine 345 is a decrypted digital signal that is "in the clear." The signal in the clear is decoded by A/V decode block 340.

In the present embodiment, A/V decode block 340 receives encrypted digital broadcast signal 370 from conditional access block 330, decrypts the signal using decryption engine 345, and decodes the video content and the audio content of digital broadcast signal 370. In the present embodiment, an MPEG (Moving Pictures Experts Group) video decoder and an AC3 (Digital Dolby) audio decoder are used; however, it is appreciated that other video or audio decoders can be used in accordance with the present invention. In addition, in one embodiment, A/V decode block 340 is capable of handling video and audio analog signals.

The inputs to graphics block 350 are the decoded video and audio digital signals from A/V decode block 340. In one embodiment, graphics block 350 also receives external audio and video analog inputs. Graphics block 350 processes the audio and video information and provides the output to, for example, a television set or a computer system (not shown) where it can be viewed and listened to.

Figure 2B is a block diagram of another embodiment of intelligent transceiver 300 in accordance with the present invention. In this embodiment, the functions of conditional access block 330 (e.g., descrambling and encrypting) of Figure 2A are incorporated into POD 320, and so intelligent transceiver 300 does not include conditional access block 330.

Continuing with reference to Figure 2B, POD 320 (e.g., a removable smart card interface) is separate from but connectable to intelligent transceiver 300. That is, POD 320 can be inserted into and coupled with intelligent transceiver 300, and POD 320 can also be detached and removed from intelligent transceiver 300. Intelligent transceiver 300 is adapted to receive different types of removable smart card interfaces, depending on the particular type of POD or smart card used by the different MSOs.

Smart card 325 is plugged into POD 320. Smart card 325 receives a scramble key for descrambling digital broadcast signal 370. POD 320 has a descrambler unit (not shown) that uses the scramble key to descramble digital broadcast signal 370. POD 320 also encrypts digital broadcast signal 370 using an encryption unit (not shown). Thus, in this embodiment, POD 320 provides a removable and portable smart card interface with conditional access functions for intelligent transceiver 300. Intelligent transceiver 300 is adapted to receive different types of PODs particular to the different MSOs and markets, and therefore can be used with a multiplicity of different types of PODs and/or smart cards. Accordingly, the same intelligent transceiver design can be used with different MSOs and markets, reducing manufacturing costs and thus reducing the cost to the consumer.

Figure 3 is a block diagram of an intelligent transceiver 400 (e.g., a bidirectional set-top box) showing additional details of the embodiments illustrated by Figures 2A and 2B. Table 1 is a list of the various elements and acronyms contained in Figure 3.

Table 1 Elements and Acronyms of Intelligent Transceiver Embodied in Figure 3

With reference to Figure 3, in the present embodiment, front-end block 310 includes an integrated circuit device 405 for handling upstream and downstream digital signals (see Figure 6). Front-end block 310 receives an in- band digital broadcast signal from a digital broadcaster via in-band tuner 401. In the present embodiment, front-end block 310 includes a cable modem coupled to MCNS FAT tuner 403. The cable modem and MCNS FAT tuner 403 can also be used for sending digital signals and information to the World Wide Web, for sending and receiving electronic mail ("e-mail"), and for exchanging information with the digital broadcast system. In one embodiment, an OOB digital broadcast signal is received via OOB tuner 402. Front-end block 310 ca also include an input/output device (e.g., modem 404) that allows a telephone or digital subscriber line (DSL) connection to be made to the World Wide Web so that bi-directional communications, including e-mail, can occur over the Internet. It is appreciated that, in other embodiments, different combinations of these elements may be present.

In one embodiment, integrated circuit device 405 is Open-Cable compliant. In this embodiment, integrated circuit device 405 can demodulate a QAM in-band signal (e.g., a 64/256 QAM in-band signal, 406) and support FEC (forward error correction) specifications (e.g., FEC J.83, Annex A B). The transport stream output can support both serial and parallel ports. Integrated circuit device 405 and OOB tuner 402 can demodulate QPSK (407) and may be compatible with DAVIC/Digicipher 2 FEC specifications. Integrated circuit device 405 can also modulate the upstream data signal to QPSK/16QAM (415) and may be capable of equalizing the FEC encoding with Starvue/MCNS/ DAVIC (408). The upstream digital data signals can also be output in analog. MAC controller 409 can comply with DAVIC/MCNS and has a router for outputting a signal to an external computer system through an Ethernet interface 413. Integrated circuit device 405 also includes DSP 414 for use with IP (Internet Protocol) telephony. It is appreciated that, in another embodiment, the devices integrated into integrated circuit device 405 can be integrated into multiple integrated circuits within front-end block 310.

In one embodiment, smart card 325 is inserted into POD 320, and intelligent transceiver 300 (specifically, conditional access block 330) contains a descrambler and encryption units (e.g., DES 490) to descramble and encrypt the digital broadcast signal. In one embodiment, smart card 325 is plugged into POD 320, and POD 320 contains descrambler and encryption units to descramble and encrypt the digital broadcast signal.

The encrypted digital signal is delivered to A/V decode block 340. In the present embodiment, a decryption engine 345 is integrated into demultiplexer ("demux") 410. Decryption engine 345 decrypts an encrypted signal (e.g., digital broadcast signal 370) received by A/V decode block 340 via conditional access block 330.

Continuing with reference to Figure 3, in the present embodiment, A/V decode block 340 includes an MPEG decoder (e.g., MP@ ML DEC block 411 ) and an audio decoder (e.g., AC-3 block 412) to decode the video and audio content of digital broadcast signal 370. Graphics block 350 processes the audio and video information received from A V decode block 340. Central processing unit 360 contains a processor (e.g., CPU core 430) and memory (e.g., instruction cache 420) for processing information and instructions used by intelligent transceiver 400.

Figure 4 is an illustration of the embodiments of intelligent transceiver 300 of Figures 2A and 2B. In accordance with the present invention, smart card 325 is inserted into POD 320, which is inserted into slot 390. Digital broadcast signal 370 is received by intelligent transceiver 300 and forwarded to POD 320, which has a descrambler unit and an encryption unit to descramble and encrypt the digital signal using a scramble key provided by smart card 325. Alternatively, the descramble and encryption units can reside in intelligent transceiver 300 (e.g., conditional access block 330 of Figure 2A). After encryption, the digital signal is decrypted in a secure location within intelligent transceiver 300, the audio and visual content are decoded and processed by intelligent transceiver 300, and the result (output 380) is sent to, for example, a television (not shown) or similar device. Figure 5 is a block diagram providing an overview of a digital broadcast system 365 in accordance with one embodiment of the present invention. Audio and video content providers 385 (e.g., a broadcast system operator or MSO) provide digital broadcast signal 370 to transceiver 300. In the present embodiment, digital broadcast signal 370 can be provided using a terrestrial broadcast (e.g., a wireless broadcast), a satellite broadcast, a terrestrial line (e.g., cable), or an Internet connection. Transceiver 300 includes a front-end block 310 containing devices needed for bi-directional communication. Transceiver 300 also includes other functional blocks (e.g., back end functional blocks 375) including modularized blocks 310, 330, 340, 350 and 360 (Figures 2A and 2B). The output of transceiver 300 includes audio and video information provided to display device 395 (e.g., a television set or a computer system) so that this information can be viewed or listened to.

Figure 6 is an illustration of the various frequencies associated with different types of broadcast digital signals in accordance with one embodiment of the present invention. In this embodiment, the frequencies in the range of approximately 5-42 MHz are known as "upstream" signals, and the frequencies in the range of approximately 54-860 MHz are known as "downstream" signals. Within the upstream range, the range of frequencies from approximately 5-26 MHz are known as "out-of-band (OOB) upstream," and the range of signals from approximately 26-42 MHz are known as "cable modem upstream." Within the downstream range, the range of frequencies from approximately 70-130 MHz are known as "out-of-band downstream." From the perspective of intelligent transceiver 300 (Figures 2A and 2B), an upstream signal is transmitted and a downstream signal is received. The OOB upstream range is used by transceiver 300 to send payment information, for example, to the broadcast system operator or MSO. The cable modem upstream range is used for communicating with the World Wide Web (the Internet), for sending e-mail, and the like. The in-band downstream range is for receiving audio and video content. The OOB downstream range is used for receiving electronic programming guide information and the scramble key used by conditional access block 330 to descramble a scrambled broadcast digital signal. Alternatively, the scramble key can be provided over the Internet via the cable modem.

Figure 7 is a flowchart of the steps in a process 700 for descrambling a scrambled digital signal in accordance with one embodiment of the present invention. With reference also to Figure 3, in the present embodiment, process 700 is implemented as program instructions that are stored in memory (e.g., instruction cache 420) and executed by a processor (e.g., CPU core 430) of intelligent transceiver 400. It is appreciated that process 700 may be utilized in other types of devices, including consumer electronic devices, where it may be necessary to descramble a digital signal.

In step 710 of Figure 7, the removable smart card interface (e.g., POD 320 of Figures 2A and 2B) appropriate to the MSO being used is selected. In accordance with the present invention, different types of removable smart card interfaces may be used, depending on the type of smart card and descrambling scheme used by the particular MSO.

In step 720 of Figure 7, POD 320 is coupled to intelligent transceiver 300 (Figures 2A and 2B). In the present embodiment, POD 320 is inserted into a slot 390 (Figure 4) in intelligent transceiver 300. In accordance with the present invention, POD 320 can be removed from intelligent transceiver 300, and a different removable smart card interface used instead.

In step 730 of Figure 7, the scramble key is received by intelligent transceiver 300 from the MSO. In one embodiment, the scramble key is received via the out-of-band tuner (OOB tuner 402 of Figure 3). In another embodiment, the scramble key is received over the Internet via a cable modem and MSNS FAT tuner 403 (Figure 3).

In step 740 of Figure 7, the descrambling scheme is enabled using the scramble key and a smart card (e.g., smart card 325 of Figures 2A and 2B) appropriate to the MSO being used. In accordance with the present invention, different types of smart cards may be used depending on the particular MSO.

In step 750 of Figure 7, with reference also to Figures 2A and 2B, a digital broadcast signal (e.g., digital broadcast signal 370) is received by intelligent transceiver 300. In the present embodiment, digital broadcast signal 370 is received by front-end block 310. Typically, digital broadcast signal 370 is scrambled but not encrypted when it is received by intelligent transceiver 300. ln step 760, in the present embodiment, digital broadcast signal 370 is sent from front-end block 310 to POD 320. In the present embodiment, POD 320 contains a descrambler unit for descrambling digital broadcast signal 370 using the scramble key and smart card 325. POD 320 can also contain an encryption unit for encrypting the descrambled digital signal. Alternatively, digital broadcast signal 370 can be descrambled and encrypted using a descrambler unit and an encryption unit residing in intelligent transceiver 300 (e.g., conditional access block 330).

In summary, in accordance with the present invention, the intelligent transceiver is adapted to receive different types of removable smart card interfaces particular to the different content providers (e.g., digital broadcast system operators or Multiple System Operators). A subscriber to a particular digital broadcast system couples the removable smart card interface (e.g., POD 320) appropriate for that system to the intelligent transceiver. A smart card provided by the digital broadcast system operator is inserted into the removable smart card interface. A scramble key provided by the digital broadcast system operator is used with the smart card to execute a scheme for descrambling the scrambled audio and video content.

In accordance with the present embodiment of the present invention, POD 320 can be inserted into and coupled with intelligent transceiver 300, as well as detached and removed from intelligent transceiver 300. Thus, POD 320 provides a removable and portable smart card interface with conditional access functions for intelligent transceiver 300.

Intelligent transceiver 300 can be used with a multiplicity of different types of PODs and/or smart cards. Thus, in accordance with the present invention, intelligent transceiver permits ready interchangeability of POD 320 depending on the descrambling scheme and smart card used by the particular MSO. Accordingly, the same intelligent transceiver design can be used with different MSOs and markets, reducing manufacturing costs and thus reducing the cost to the consumer.

The present invention thus provides an apparatus and method that can allow greater flexibility with regard to the design of transceivers (e.g., a set-top boxes) for different markets and for different digital broadcast system operators, thereby reducing costs to manufacturers and consumers.

The preferred embodiment of the present invention, modular conditional access block, is thus described. While the present invention has been described in particular embodiments, it should be appreciated that the present invention should not be construed as limited by such embodiments, but rather construed according to the below claims.

Claims

CLAIMSWhat is claimed is:

1. An apparatus comprising: a smart card interface connectable to an intelligent transceiver; said smart card interface adapted to receive a smart card, said smart card for enabling a process for descrambling scrambled digital signals; wherein said smart card interface can be selectively coupled to and detached from said intelligent transceiver and said smart card interface is particular to a digital broadcast system operator.

2. The apparatus of Claim 1 , wherein said apparatus is a digital broadcast system said apparatus further comprising: an intelligent transceiver, said intelligent transceiver adapted to receive different types of smart card interfaces, wherein said smart card interface being removable and connectable to said intelligent transceiver.

3. A method comprising the steps of: a) receiving a scramble key at an intelligent transceiver; b) enabling a descrambling scheme using said scramble key and a smart card, wherein said smart card is coupled to a removable smart card interface particular to a digital broadcast system; c) receiving in-band digital signals using an in-band tuner of said intelligent transceiver, said in-band digital signals comprising scrambled audio content and scrambled video content, wherein said intelligent transceiver is adapted to receive different types of removable smart card interfaces; and d) descrambling said scrambled audio content and said scrambled video content.

4. The method as recited in Claim 3 wherein said step a) comprises the step of: al) receiving out-of-band digital signals using an out-of-band tuner of said intelligent transceiver, said out-of-band digital signals comprising said scramble key.

5. The method as recited in Claim 3 wherein said step a) comprises the step of: a2) receiving digital signals via the Internet using a tuner coupled with a cable modem, said digital signals received via the Internet comprising said scramble key.

6. The method as recited in Claim 3 wherein said step d) is performed using a descrambler unit incorporated into said intelligent transceiver.

7. The method as recited in Claim 3 wherein said step d) is performed using a descrambler unit incorporated into said removable smart card interface.

8. The method as recited in Claim 3 further comprising the step of: e) encrypting said in-band digital signal.

9. The method as recited in Claim 8 wherein said step e) is performed using an encryption unit incorporated into said intelligent transceiver.

10. The method as recited in Claim 8 wherein said step e) is performed using an encryption unit incorporated into said removable smart card interface.

1 1. The apparatus of Claims 1 -2 or the method of Claims 3-10, wherein said smart card interface comprises a descrambler unit for descrambling said scrambled digital signals.

12. The apparatus or method of Claim 1 1 wherein said smart card interface comprises an encryption unit for encrypting a digital signal.

13. The apparatus of Claims 1 -2 or the method of Claims 3-10, wherein said intelligent transceiver comprises: a bus; an in-band tuner coupled to said bus and adapted to receive in-band digital signals comprising audio content and video content; and a circuit coupled to said tuner for generating an output audio/video signal for rendering on a display device.

14. The apparatus or method of Claim 13 wherein said intelligent transceiver further comprises: an out-of-band tuner coupled to said bus and adapted to receive out-of-band digital signals, said out-of-band digital signals comprising a scramble key used by said smart card to, descramble said scrambled digital signals.

15. The apparatus or method of Claim 13 wherein said intelligent transceiver further comprises: a tuner adapted to send and receive digital signals using a cable modem, said digital signals comprising a scramble key used by said smart card to descramble said scrambled digital signals.

16. The apparatus or method of Claim 13 wherein said intelligent transceiver further comprises: a descrambler unit for descrambling said scrambled digital signal.

17. The apparatus or method of Claim 13 wherein said intelligent transceiver further comprises: an encryption unit for encrypting a digital signal.

18. The apparatus or method of Claim 13 wherein said intelligent transceiver further comprises: a tuner adapted to send and receive digital signals using a cable modem.

19. The apparatus or method of Claim 18 wherein said tuner receives digital signals via the Internet, said digital signals comprising a scramble key used to descramble said scrambled digital signal.

20. The apparatus or method of Claim 13 wherein said intelligent transceiver further comprises: an integrated circuit device coupled to said bus and adapted to receive an encrypted digital signal, said integrated circuit device comprising a functional block and a decryption engine integrated therein, wherein said functional block is for decoding said audio content and said video content; and wherein said decryption engine is configured to decrypt said encrypted digital signal received by said integrated circuit device and supply a decrypted digital signal to said functional block.