KR101110678B1 - Security method for conditional access system software in downloadable conditional access system - Google Patents

Abstract

The present invention relates to a security method of CA system software in a downloadable CA system in which a CAS vendor server directly creates / distributes / manages a CAS client personalized image. More specifically, the CAS vendor server includes a CAS from a master CAS client image. By directly creating a client personalized image and passing it to the DCAS server, the master CAS client image does not exist in the DCAS server, thereby preventing the external leakage of the master CAS client image, thereby enhancing the security of the CAS system, and the CAS vendor server provides the DCAS Create and deliver as many CAS client personalization images as requested by the server, and forward each personalization image through personalization between the DCAS server and the DCAS host to manage the distribution of CAS client personalization images by CAS vendor policy. To prevent indiscriminate creation and distribution of CAS client images by the operators, and the CAS vendor server creates and distributes different CAS client personalization images to the DCAS server according to the DCAS host, so that other CAS client personalization images may be exposed to security even if they are exposed to security. The security of other CAS clients can be maintained without affecting the security of the client's image.

DCAS, CAS, Cable Broadcasting, Cable Broadcasting, Broadcasting, Security Module, Security

Description

SECURITY METHOD FOR CONDITIONAL ACCESS SYSTEM SOFTWARE IN DOWNLOADABLE CONDITIONAL ACCESS SYSTEM}

The present invention relates to a security method of CA system software in a downloadable CA system in which a CAS vendor server directly creates / distributes / manages a CAS client personalized image. Particularly, the CAS vendor server uses a CAS client personalized image from a master CAS client image. Directly to the DCAS server, and the CAS vendor server generates and delivers the CAS client personalization images as required by the DCAS server, and delivers each personalized image through personalization between the DCAS server and the DCAS host. The present invention relates to a security method of CA system software in a downloadable CA system where a CAS vendor server generates different CAS client personalized images according to DCAS hosts and distributes them to the DCAS server.

A conditional access system (CAS) is a system that allows a paid broadcaster to watch a broadcast only to a user who paid a subscription fee, and is used for content protection in the digital broadcasting market together with digital right management (DRM). In order to use the CA system service, a set top box (STB) capable of receiving digital broadcasting is required, and a system capable of driving CAS software must be built in the set top box.

There are two methods for embedding the CAS system in the set-top box. One is to embed the CAS driving module inside the set-top box, and the other is to use the CAS driving module in the common interface module of the CAS system installed in the set-top box main body having the common interface. That's the way it is. The process of embedding a module necessary for driving a CAS system in the set-top box or a common interface module is called porting. A set-top box or a common interface module to which a specific CAS system is ported is reused when the broadcaster changes to another CAS system. impossible.

Therefore, the method of using the CAS system is dependent on the CAS vendor after the broadcaster selects a specific CAS system. In addition, when a broadcasting company uses a specific CAS system and changes to another CAS vendor's system, users have to repurchase a set-top box or a common interface module. There is a problem of failure of the set-top box or module due to the heat and increase in unit cost of the set-top box.

In order to solve the problems of the pay-TV market, a downloadable conditional access system (DCAS) has been proposed. The DCAS system downloads and installs a CAS client image onto a secure micro chip (SM) of a DCAS host without embedding a CAS driving module that was dependent on a specific CAS vendor in a set-top box or a common interface module. By making it possible to use, it is a technology that allows a flexible broadcasting service even if a paying broadcaster adds or changes a CAS system.

The CAS client image for using the DCAS system is provided by a CAS vendor, and the DCAS server downloads the CAS client image to the DCAS host according to the policy of the operator. At this time, the image transmitted from the DCAS server to the DCAS host is a CAS system security module as a master CAS client image.

In such a DCAS system, the CAS vendor only participates in producing a CAS client image, and thus, a CAS client delivered to the DCAS system may be vulnerable to security at any time. For example, if the master CAS client image stored in the DCAS server is leaked to the outside, there is a problem that the CAS system currently being used by the CAS vendor becomes incapacitated, which causes a dispute about the responsibility of the DCAS vendor and the CAS vendor. May occur. Or, since there is no subscriber information in the case of the master CAS client image, there is a problem that a paying broadcasting company can indiscriminately generate a CAS client and transmit it to the DCAS host using the master CAS client image received from the CAS vendor.

An object of the embodiment of the present invention for improving the above-mentioned problem is that the CAS vendor server directly generates a CAS client personalized image from the master CAS client image and delivers it to the DCAS server so that the master CAS client image does not exist in the DCAS server. It is to provide the security method of CA system software in downloadable CA system which can prevent external leakage of PC.

Another object of the embodiment of the present invention is that the CAS vendor server generates and delivers as many CAS client personalized images as requested by the DCAS server, and delivers each personalized image through personalization between the DCAS server and the DCAS host. It provides a security method of CA system software in downloadable CA system which manages distribution of personalized image of CAS client.

Another object of the embodiment of the present invention is that the CAS vendor server generates different CAS client personalized images according to the DCAS host and distributes them to the DCAS server, so that even if one of the CAS client personalized images is exposed to security, the security of the image of another CAS client Is to provide a security method for CA system software in a downloadable CA system without affecting it.

In order to achieve the above object, the security method of the CA system software in the downloadable CA system according to an embodiment of the present invention is CAS CAS headend using a master CAS client image CAS corresponding to a specific DCAS host Generating a client personalization image, the DCAS headend managing the DCAS host downloading the CAS client personalization image from the CAS vendor headend, and the DCAS host sending the CAS client personalization image from the DCAS headend It characterized in that it comprises a receiving step.

The security method of CA system software in the downloadable CA system according to an embodiment of the present invention includes the steps of the DCAS host installing and initializing the CAS client personalized image, and the DCAS host completely installing the CAS client personalized image. Afterwards, the method may further include updating the corresponding information in the secure micro (SM).

In the downloadable CA system security method of the CA system software, the CAS vendor server directly generates a CAS client personalized image from the master CAS client image and delivers it to the DCAS server so that the master CAS client image is transferred to the DCAS server. Since it does not exist, the security of the CAS system can be improved by preventing external leakage of the master CAS client image.

In the downloadable CA system security method of the CA system software, the CAS vendor server generates and delivers the CAS client personalized images as required by the DCAS server, and each personalized image is again transferred to the DCAS server and the DCAS. By delivering through personalization with host, CAS vendor's policy can manage distribution of personalized image of CAS client, thereby preventing indiscriminate creation and distribution of CAS client image.

In the downloadable CA system security method according to the embodiment of the present invention, a CAS vendor server generates a different CAS client personalized image according to the DCAS host and distributes the CAS client personalized image to the DCAS server so that one of the CAS client personalized images is secured. Even if it is exposed to other CAS clients, the security of other CAS clients can be maintained by not affecting the security of images of other CAS clients.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

1 is a block diagram of a downloadable CA system for explaining a security method of CA system software according to an embodiment of the present invention, wherein the CA system creates or manages a master CAS client image; Using this, a CAS vendor headend 200 for supplying a CAS client personalized image, a DCAS headend 100 for receiving the CAS client personalized image from the CAS vendor headend 200 and transmitting it to a DCAS host, and the DCAS head And a DCAS host SM information database server 30 that manages the SM (Secure Micro) related information of the DCAS host managed by the end 100 and the CAS client personalized image information.

The CAS vendor headend 200 includes a CAS server 220 for managing a master CAS client image and an initialization entitlement management message (EMM), and a CAS client personalization server for generating the master CAS client image as a personalized image ( 230 and a subscriber management server 210 (SMS: Subscriber Management System) for managing subscriber information.

The CAS server 220 generates or manages a master CAS client image, manages the DCAS host user's credential management information, and transmits it in the form of an entitlement management message (EMM) upon external request.

The CAS client personalization server 230 generates the master CAS client image as a CAS client personalization image, and transmits the generated CAS client personalization image to the DCAS headend 100.

The CAS client personalization server 230 directly generates a CAS client personalization image from the master CAS client image and delivers it to the DCAS headend 100 so that the master CAS client image does not exist in the DCAS headend 100 so that the DCAS head It is possible to prevent external leakage of the master CAS client image from the end 100.

The subscriber management server 210 transmits the DCAS host requesting the installation or update of the CAS client to the CAS server 220 when the DCAS headend 100 requests the initialization EMM to the CAS server 220. Send the initialization EMM to the DCAS host.

The CAS vendor headend 200 generates and sends a CAS client personalized image as many as requested by the DCAS headend 100, and the CAS server 220 requests the DCAS host receiving the CAS client personalized image. By sending the initialization EMM directly, the CAS vendor's policy can manage the distribution of personalized images of CAS clients, thus preventing operators from indiscriminate creation and distribution of CAS client images.

The DCAS headend 100 is an authentication proxy server 120 for performing mutual authentication with a security module of a DCAS host (AP: Authentication Proxy), and a policy server for transmitting various policy information necessary for DCAS service operation and management to each server ( 130, DPS: Encrypts the CAS client image using the encryption key received from the DCAS Provisioning System) and the authentication proxy server 120, and downloads according to the transmission mechanism (TFTP, HTTP, etc.) instructed by the policy server 130. Integrated personalization system server 140, IPS (Integrated Personalization Server) to proceed with the procedure, and includes a key management server (110, LKS: Local Key Server) that manages all key-related information operated in the DCAS system.

The authentication proxy server 120 generates a session key and shares the session key with a DCAS host. The session key is a key used to encrypt / decrypt CAS client images and DCAS messages. In addition, the authentication proxy server 120 receives information related to the download policy from the policy server 130, and performs the processing required for downloading the CAS client image to the integrated personalization system server 140 in accordance with the received information. Instruct them to do it.

The integrated personalization system server 140 performs a process required for downloading the CAS client image encrypted with the session key according to the download policy determined by the policy server 130.

The key management server 110 stores / manages security-related keys and ID information operating in the DCAS network, and performs history management for them.

The DCAS host SM information database server 30 stores a database of SM unique information and CAS client personalized images of DCAS hosts managed by the DCAS headend 100, and stores the DCAS headend 100 and the database. Communication with the CAS vendor headend 200 may transmit the SM unique information and the image information to both sides.

In addition, although the DCAS host SM information database server 30 may be included in any one of the DCAS headend 100 and the CAS vendor headend 200, the DCAS host SM information database server 30 may be included in the CAS vendor headend 200. It is preferable.

The CAS vendor headend 200 generates a different CAS client personalized image using the SM unique information of the DCAS host stored in the DCAS host SM information database server 30 and distributes them to the DCAS headend 100. Even if one of the CAS client personalized images is exposed to security, the security of the other CAS client can be maintained by not affecting the security of the image of the other CAS client.

2 is a data flow diagram of a security method of CA system software according to an embodiment of the present invention.

Before a predetermined server in the CAS vendor headend generates a master CAS client image, the memory map is divided into an SM interface area and a CAS security module area, and then a master image is generated.

The CAS client personalization server included in the CAS vendor headend generates a CAS client personalization image to be supplied to the DCAS headend using a master CAS client image obtained from a predetermined server in the CAS vendor headend.

The CAS client personalized image is divided into a header area, an SM interface area, and a CAS security module area. The CAS client personalization server encrypts the CAS security module of the master image, and stores the personalization information of the DCAS host, the SM interface of the master image, and the encrypted CAS security module, respectively, in the header area, SM interface area, and CAS security module. After placing in an area, the package is generated to generate a plurality of personalized images (1).

After the process, the CAS client personalization server transmits a plurality of generated personalization images to the DCAS headend (2), and unique information of the SM to the DCAS host SM database server shared by the DCAS headend and the CAS vendor head end. And update the image information. In addition, the CAS client personalization server updates the database of the CAS server with encryption key information used for personalization of the DCAS host (3).

Thereafter, when a specific DCAS host connects to the network and needs to install or update a limited reception module to request a CAS client personalization image to the DCAS headend (4), authentication is performed between the DCAS headend and the DCAS host. Go through the process. The DCAS headend requesting the CAS client personalized image requests the Trusted Authority (TA) to authenticate the DCAS host (5), and the DCAS headend receives an authentication response from the TA (6). When the authentication is completed, the DCAS headend retrieves the CAS client personalized image corresponding to the DCAS host from the DCAS host SM database server, encrypts the image using a session key (7), and transmits the image to the DCAS host. (8). The DCAS host decrypts the received CAS client personalized image using the session key (9).

Thereafter, the DCAS host reads the header information of the downloaded CAS client personalized image, acquires the size of the SM interface region, and installs and executes the SM interface module in the defined memory region to perform initialization (10).

When the SM interface module of the CAS client personalization image is normally executed, the executed SM interface module acquires SM related information of the current DCAS host, generates SM unique information necessary for authentication or operation of the CAS client, and sends the SMAS information to the DCAS host. Request initialization of the CAS client.

The DCAS host receiving the request requests CAS client initialization data to the DCAS headend (11), and the DCAS headend transmits SM unique information and personalization information of the DCAS host to an SMS server to initialize the CAS client. Request (12).

Upon receiving the request, the SMS server requests transmission of an Entitlement Management Message (EMM) to the CAS server (13). The CAS server searches an internal database and initializes data corresponding to the personalization information to the initialization EMM. After generating the response to the SMS server (14). The SMS server sends a transmission response of the initialization EMM to the DCAS headend (15), and the CAS server sends the initialization EMM to the DCAS host (16).

The DCAS host delivers the received initialization EMM data to a CAS client, and the CAS client obtains a decryption key using the initialization EMM data. After acquiring the decryption key, the CAS client instructs the SM to decrypt the encrypted CAS security module region in the CAS client personalized image, and the SM reads the header information to obtain the size of the CAS security module region. Thereafter, the CAS security module is decrypted and loaded with the obtained key in the designated area (17, 18).

After the CAS client personalized image is completely loaded into the SM of the DCAS host, the CAS client writes the corresponding information in the CAS data area and skips the above process after the next boot. In addition, when the CAS client is updated, the process is performed after initializing data in the CAS data area.

FIG. 3 illustrates a structure of an encrypted personalized image and a memory map after the personalized image is loaded in the SM region of the DCAS host according to an embodiment of the present invention.

The CAS client personalized image includes a personalization information header 31, an SM interface 32, and an encrypted CAS security module 33.

The personalization information header 31 stores the personalization information of the CAS client personalization image and the area size of the SM interface and the CAS security module, and when the respective parts are installed, the area can be set.

When the CAS client requests initialization after the SM interface 32 is installed in the SM interface region 37, the CAS vendor headend sends an initialization EMM to the corresponding DCAS host so that the CAS client can perform initialization.

Thereafter, the CAS security module 33 is decrypted using the decryption key included in the initialization EMM, and then the decrypted CAS security module is installed in the CAS security module area 36.

After the CAS client personalized image is completely loaded in the SM of the DCAS host, the DCAS host updates the encryption key data in the CAS encryption key data area 35 and stores the corresponding information in the CAS data area 34. . In addition, when the CAS client is updated, the process is performed after initializing the data in the CAS data area 34.

1 is a block diagram of a downloadable DCS for explaining a security method of CA according to an embodiment of the present invention.

2 is a data flow diagram of a security method of CA system software according to an embodiment of the present invention.

Figure 3 is a memory map after the structure of the encrypted personalized image and the personalized image is loaded in the SM area in the DCAS host according to an embodiment of the present invention.

** Description of symbols for the main parts of the drawing **

10: TA 20: CMTS

30: DCAS Host SM Information Database Server

100: DCAS headend 200: CAS vendor headend

220: CAS server 230: CAS client personalization server

Claims (13)

Downloadable CA system that includes a CAS vendor headend that manages a master CAS client image, a DCAS headend that receives CAS client images from the CAS vendor headend, and a DCAS host that receives CAS client images from the DCAS headend (DCAS). In the method of security of the CA software, a) the CAS vendor headend using the master CAS client image to generate a CAS client personalized image corresponding to the particular DCAS host; b) the DCAS headend managing the DCAS host downloads the CAS client personalized image from the CAS vendor headend and sends it to the DCAS host; c) installing the CAS client personalized image by the DCAS host, transmitting the SM (Secure Micro) unique information to the CAS vendor headend, and receiving initialization data according to the DCAS host to initialize the CAS client; Dividing the CAS vendor headend into an interface module of SM (Secure Micro) that requests initialization of the CAS client in the DCAS host and a CAS security module that drives a CAS system when the CAS client personalized image is generated; And adding an initialization routine of the CAS client personalized image into the SM interface module. The method of claim 1, wherein step a) And the CAS vendor headend generates the CAS client personalized image using the unique information of the SM (Secure Micro) of the DCAS host. The method of claim 1, wherein b) The DCAS server selects the CAS client personalized image of the SM using the unique information of the SM of the DCAS host requested, and transmits the selected image to the DCAS host. Security method. The method of claim 1, Generating, by the CAS vendor headend, the CAS client personalized image, updating SM unique information and image related information of the DCAS host in a database; And encrypting, by the CAS vendor headend, the personalized information of the DCAS host in a database. The method of claim 1, And after the DCAS host completely installs the CAS client personalized image, updating the corresponding information in the secure micro (SM). delete The method of claim 1, The CAS vendor headend encrypts the CAS security module portion of the CAS client personalization image using the unique information of the SM (Secure Micro) of the DCAS host, and then uses the personalization information of the DCAS host as header information. And a step of packaging the CAS client module with the encrypted CAS security module and generating the CAS client personalized image. The method of claim 7, wherein Installing and driving an SM interface module by reading, by the DCAS host, header information of the CAS client personalized image transmitted to the secure micro (SM); Requesting, by the driven SM interface module, initialization data of a CAS client security module to the DCAS host; And transmitting, by the DCAS host, the unique information of the corresponding SM to the DCAS server, and requesting initialization data of the CAS security module. The method of claim 8, The CAS vendor headend receiving the request from the DCAS server further transmits personalization information of the CAS client as initialization data to the DCAS host. Way. The method of claim 9, The DCAS host receiving the initialization data from the CAS vendor headend; And acquiring an encryption key of the encrypted CAS security module using the initialization data and loading the encrypted key into a designated area of the SM. The method of claim 9, And after the installation of the CAS client personalization image, the DCAS host further updates the encryption key data in the CAS encryption key data area. The method of claim 9, When the DCAS host is re-executed, if the CAS client personalized image is not updated in the DCAS server, the DCAS host decrypts and loads the CAS security module portion with an encryption key stored in the SM without requesting initialization data. A security method for CA system software in a downloadable CA system. The method of claim 1, wherein step a) And the CAS vendor headend generates a CAS client personalized image corresponding to a specific DCAS host when the DCAS headend makes a request to the CAS vendor headend.

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