KR20090050331A - Mobile cas client device for dmb - Google Patents

Abstract

The present invention relates to a reception limitation system for digital multimedia broadcasting, and more particularly, to a portable client device of a reception restriction system. According to the present invention, a DMB CAS client device for receiving a DMB stream scrambled by CW and an EMM / ECM encrypted with CW, and providing a descrambled DMB stream to a multimedia device, comprising: connecting to an MCU and the multimedia device. A memory for storing a CAS client library having a USB interface, a descrambler for descrambling the scrambled DMB stream using a CW, and a CAS for extracting the CW from the encrypted ECM / EMM and providing the descrambler to the descrambler. A CAS client device comprising a security chip is provided.

DMB, Broadcasting, Reception Restriction, USB, Mobile, Security Chip

Description

Portable Client Device of DMB Restriction System {MOBILE CAS CLIENT DEVICE FOR DMB}

The present invention relates to a reception limitation system for digital multimedia broadcasting, and more particularly, to a portable client device of a reception restriction system.

As digitalization of broadcasting has recently progressed, digital multimedia broadcasting (DMB) services are in the spotlight. The core technology of DMB service is conditional access system (CAS). CAS is a system that allows only subscribers with viewing rights to watch a specific program, and means a series of processes that allow each digital broadcast receiver to determine whether a receiver can receive a particular program.

The CAS consists of a transmitting side (CAS server) that encrypts and transmits a signal, and a receiving side (CAS client) that receives and decrypts the encrypted signal. In the CAS server, the A / V stream is scrambled with a key (CW, Control Word), and the CW is encrypted and loaded on the Entitlement Management Message (EMM) and Entitlement Control Message (ECM) data and transmitted to the receiver. The CAS client decodes the EMM and the ECM by using the viewer's smart card, extracts the CW, and then descrambles the descrambled A / V stream using the extracted CW. Since a conventional CAS client is used in a built-in DMB viewing terminal, broadcasting can be viewed only through a terminal on which a CAS client is installed. Therefore, even subscribers with viewing rights cannot use the DMB service on other multimedia devices that can support only unencrypted data because the CAS client is not installed. In order to alleviate this inconvenience, a portable CAS client device configured to use DMB service in any type of multimedia device is required.

It is an object of the present invention to provide a CAS client device that enables a viewer to view DMB regardless of the type of multimedia device.

According to an aspect of the present invention, a DMB CAS client device for receiving a DMB stream scrambled by CW and an EMM / ECM encrypted with CW to provide a descrambled DMB stream to a multimedia device, comprising: an MCU and the multimedia device. A memory configured to store a CAS client library having a USB interface for connecting to the USB interface, a descrambler configured to descramble the scrambled DMB stream using a CW, and extract the CW from the encrypted ECM / EMM to the descrambler. A CAS client device including a CAS security chip is provided.

The memory may be an internal memory of the MCU.

The CAS client device may further comprise an additional memory for storing the CAS client library.

The CAS client library may further include a software upgrade module.

According to the configuration of the present invention can achieve all the objects of the present invention described above. Specifically, since a portable CAS client device in the form of a USB drive is provided, the DMB service can be easily used even in a multimedia device in which the CAS client module is not installed.

So far, there have been some difficulties in applying the CAS client to USB drives. First, there is a physical size problem in applying a smart card processor. USB drives are typically characterized by a small overall PCB size, which makes them physically difficult to add hardware components for CAS clients. In order to solve this problem, in the present invention, the embedded CAS was implemented by maximizing the internal memory area of the MCU used in the conventional USB drive, and the size of the smart card processor was about 6 × 6mm.

In addition, when simply using a smart card processor on a USB drive, the EC client and EMM are filtered from the CAS client library ported to the host device and transferred back to the smart card processor to extract the CW and back to the CAS client. Because of this, the following problems occur. The first is that there is no USB interface protocol to correctly handle ECM / EMM and CW. The second is that the CW must be delivered to the descrambler of the CAS client library located on the host device in a timely manner, and the third is a congestion in the data flow. (congestion) is a problem. To solve this problem, the present invention allows ECM / EMM filtering and CW processing on the data flow to be performed on the USB drive.

In addition, porting CAS client libraries related to media players linked to a USB drive should be ported, and porting CAS may be difficult depending on the media player environment linked to CAS-applied content (video / audio / data). have. In the present invention, in order to solve this problem, the CAS library is directly ported to the USB drive, and the descrambled stream is delivered to the media player.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

1, there is shown a portable CAS client device 10 and a multimedia device 100 in which a media player is installed, according to an embodiment of the present invention. The multimedia apparatus 100 includes a universal serial bus (USB) port 110. The CAS client device 10 is a USB drive mounted to the USB port 110 of the multimedia device 100.

Referring to FIG. 2, the CAS client device 10 includes a microcontroller unit (MCU) 20, a CAS security chip 30, an additional memory 50, a high speed USB interface 40, And an RF tuner 60 and a DAB channel decoder 70. The MCU 20 delivers the stream to the multimedia device 100 through the interface 40. The MCU 20 has its own internal memory 20. Internal memory 20 is ROM and RAM, and CAS client library is stored. If the capacity of the memory 20 is insufficient, the additional memory 50 composed of ROM and RAM is installed to store the CAS client library 52. The CAS client libraries 24 and 52 have necessary software such as a descrambler to be described later, and these software will be described later. The CAS security chip 30 receives the encrypted EMM / ECM from the MCU 20, decrypts it, and extracts CW from it. The extracted CW is sent back to the MCU (20). The high speed USB interface 40 connects the CAS client device 10 to the multimedia device 100.

Referring to Fig. 3, software of a CAS client includes an RF & DMB channel decoder 90, a demultiplexer 91, a descrambler 92, a TS / sub channel parser and database 93, a CAS applet and a database ( 94), CAS software upgrade 95, and high speed USB interface module 96. The demultiplexer 91 filters data received from the RF and DMB channel decoder 90 and exchanges data with the TS / sub channel parser and database. Demultiplexer 91 demultiplexes scrambled DMB MPEG-2 TS, scrambled DAB MPEG-2 audio, and scrambled DAB data.

In the TS / subchannel parser and database 93, the parser parses the TS / subchannel to obtain ECM / EMM data from DAB audio, data or TS streams. The parser also communicates with the demultiplexer 91 to filter the PMT and SubCA prefix tables, and parses the ECM / EMM data and sends it to the CAS applet and database 94 to extract CW from the given data. In addition, in the TS / subchannel parser and database 93, the database is optional to maintain a channel database and store the retrieved channels and their information.

The CAS applet and the database 94 decrypts the ECM / EMM data received from the TS / subchannel parser and the database 93 using the CAS security chip (30 in FIG. 2), extracts the CW, and then extracts the extracted CW. To the descrambler 92. The CAS descrambler 92 descrambles the stream using the CW received from the CAS applet and the database 94 and outputs it to the multimedia device (100 in FIG. 2) through the high-speed USB interface module 96. The descrambler 92 descrambles scrambled DMB MPEG-2 TS, scrambled DAB MPEG-2 audio, and scrambled DAB data.

The CAS software upgrade 95 receives and updates CAS software via a USB device or over-the-air (OTA), allowing users to always use the latest CAS software.

 The high speed USB interface module 96 acts as an interface between the multimedia device (100 in FIG. 2) and the CAS client device (10 in FIG. 2). The high speed USB interface module 96 has a protocol for communication between two devices (10, 100 in Fig. 2). TS (Transport Stream) data is transferred to the multimedia device (100 in FIG. 2) via the high speed USB interface module 96. The high speed USB interface module 96 also receives commands from the multimedia device (100 in FIG. 2) to operate the CAS. For example, in order to identify and descramble the scrambled stream, the multimedia apparatus (100 in FIG. 2) must notify the CAS client of all channel changes, which is done by a channel change notification command. The multimedia apparatus 100 of FIG. 2 may request channel information, send channel notification, or send data such as a tuning command to the CAS client.

Now, the operation of this embodiment will be described in detail with reference to Figs.

The DMB data including the encrypted stream received through the RF tuner 60 and the DAB channel decoder 70 is stored in various software of the CAS client library stored in the internal memory 20 and the additional memory 50 of the MCU 20. Is processed by First, it is filtered by the demultiplexer 91 and transmitted to the TS / subchannel parser 93. The TS / subchannel parser 93 parses the TS / subchannel to obtain encrypted ECM / EMM data and transmits it to the CAS applet and database 94. The CAS applet and the database 94 extract the CW from the ECM / EMM using the CAS security chip 30. The extracted CW is sent to the CAS descrambler 92, the CAS descrambler 92 descrambles the broadcast stream encrypted using the CW and sends the descrambler 92 to the multimedia apparatus 100 through the high speed USB interface module 96. The user can watch the broadcast via the media player 103.

Although the present invention has been described with reference to the above embodiments, the present invention is not limited thereto. Those skilled in the art will appreciate that modifications and variations can be made without departing from the spirit and scope of the present invention and that such modifications and variations also fall within the present invention.

1 is a perspective view showing a PDA and a reception limiter according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a hardware configuration of the reception limiter shown in FIG.

3 is a block diagram showing the software configuration of the reception limiter shown in FIG.

Claims (4)

A DMB CAS client device that receives a DMB stream scrambled by CW and an EMM / ECM encrypted CW and provides a descrambled DMB stream to a multimedia device. With MCU, A USB interface for connecting to the multimedia device; A memory storing a CAS client library including a descrambler for descrambling the scrambled DMB stream using CW; And a CAS security chip for extracting the CW from the encrypted ECM / EMM and providing the descrambler to the descrambler. The CAS client device of claim 1, wherein the memory is an internal memory of the MCU. 3. The CAS client device of claim 2, further comprising additional memory for storing the CAS client library. 4. The CAS client device of any one of claims 1 to 3, wherein the CAS client library further comprises a software upgrade module.

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