KR101483187B1 - Conditional access system and method exchanging randon value - Google Patents

Abstract

A method and system for restricting reception through exchange of random values is provided. A method for restricting reception through exchange of random values includes receiving first secret key generation information including a terminal random value generated at a user terminal from a user terminal, generating a server random value of the reception restriction system, Generating a secret key using the terminal random value and the generated server random value and generating second secret key generation information including the server random value and providing the second secret key generation information to the user terminal, The key generation information is used to generate a secret key used for decryption of the entitlement control message (EMM).

CAS, random value, exchange, authentication processing, secret key generation, EMM

Description

TECHNICAL FIELD [0001] The present invention relates to a system and method for restricting reception through exchange of random values,

The present invention relates to a reception restriction system and method by exchanging random values, and more particularly, to a reception restriction system and method for generating a secret key every time a user terminal is booted while exchanging random values with each other will be.

With the spread of the Internet and the development of digital broadcasting technology, the use of the two-way broadcasting service provided using the high-speed Internet network is increasing.

The bidirectional broadcasting service is a service for providing information services, video contents, broadcasting, and the like to a bidirectional broadcasting receiver (for example, IPTV, DMB receiver, set-top box, etc.) Various contents and additional services provided by the Internet such as home banking, online games, and MP3 can be provided.

Meanwhile, the bidirectional broadcasting service mainly adopts a conditional access system (CAS), which is a download security solution for selectively providing contents to subscribers. (CAS) is a system that allows paid subscribers to view pay-per-view broadcasts. It is a core solution for pay-TV companies such as satellite broadcasting and cable broadcasting and terrestrial broadcasters that are free of charge but are likely to be paid for .

A general reception restriction system (hereinafter referred to as CAS) will be described as follows.

When contents such as video, audio, and data are supplied from program providers (PPs), information on the contents is also supplied, and work on PPVs, NVODs, IPPVs, and relay channels is scheduled through these information items, Information and CW (Control Word) information from the scrambler are interlocked to generate an ECM and an EMM (Entitlement Management Message) encrypted in the CAS.

An ECM (Entitlement Control Message) is an entitlement control message used for content protection. An ECM generator receives program information and package information from a broadcast schedule generator, and generates an ECM. The EMM is an entitlement management message used for subscriber authentication. The EMM generator receives subscriber information and purchase information from the subscriber management system, and generates an EMM.

The generated ECM and EMM are transmitted to a multiplexer, multiplexed with a compressed video / audio stream, and then transmitted to a receiver of the home. In the home, the ECM and the EMM are embedded in a set-top box (STB) Multiplexes and encrypts multiplexed video, audio, and data through receiver CA software that performs authentication and filtering, and mutual authentication between the smart card and the receiver. However, it does not support compression / multiplexing and encryption of PPV, NVOD, IPPV, Paid services will have usage restrictions based on the credit status of the smart card.

The smart card is a card with a built-in chip having its own processor and memory, which is provided to the subscriber for watching satellite broadcasting. The receiver finds the CW (Control Word) necessary for decoding through the smart card, Set-top box access is allowed.

However, since the conventional CAS as described above generates the secret key using the fixed secret value of the set-top box and does not perform separate authentication for generating the secret key between the set-top box and the reception restriction system, There was a vulnerable problem.

In addition, since the conventional CAS decrypts the EMM by using the key stored in the smart card, there is a problem that the security is weak, for example, the smart card must be replaced when the smart card is hacked.

Further, in order to solve the conventional weak security problem, a plurality of EMMs have been generated by encrypting the CW with the channel key and re-encrypting the channel key with the key stored in the smart card, thus complicating the encryption / decryption of the content.

An embodiment of the present invention provides a reception restriction system and method for generating a secret key while exchanging random values with each other with a user terminal.

In addition, an embodiment of the present invention provides a reception restriction system and method for performing mutual authentication with a user terminal and generating a secret key.

In addition, an embodiment of the present invention provides a reception restriction system and method capable of generating an EMM (Entitlement Management Message) using a secret key generated each time a user terminal is booted.

As a technical means for accomplishing the above technical object, a first aspect of the present invention is a method for receiving first secret key generation information including a terminal random value generated at a user terminal from a user terminal, Generating a server random value, generating a secret key using the terminal random value and the generated server random value, and generating second secret key generation information including the server random value to the user terminal And the second secret key generation information is used for generating a secret key used for decrypting the entitlement control message (EMM).

According to a second aspect of the present invention, there is provided a reception restriction system for exchanging random values, comprising: a first secret key generation unit configured to generate first secret key generation information in which a secret value of the user terminal and a terminal random value generated in the user terminal are combined, A terminal random value extractor for extracting a terminal random value of the user terminal from the first secret key generation information, a server random value generator for generating a random value of the reception restriction system, A secret key generation unit for generating a secret key using the generated server random value and second secret key generation information in which a server random value and a secret value of the reception restriction system are combined to generate second secret key generation information, And a second secret-key-generation-information generating unit for providing information to the user terminal, wherein the second secret- The present invention can provide a reception restriction system through the exchange of random values, which is provided to the base station and used to generate a secret key used for decryption of the entitlement control message (EMM).

The third aspect of the present invention also provides a method for generating a random number, comprising: generating a random value generator for generating a random value of the user terminal; generating first secret key generation information that combines the random value of the terminal and the secret value of the user terminal, A first secret key generation information generation unit for generating secret key generation information for a first secret key generated by the reception restriction system and providing the secret key generation information to the reception restriction system, A server random value extractor for extracting a server random value of the reception restriction system from the second secret key generation information, and a server random value extractor for extracting a server random value from the server random value and the generated random random number, Wherein the first secret key generation information is provided to the reception restriction system, Message may provide the user terminal to release the conditional access content through the exchange of the random value will be used for generation of the secret key used for the generation of (EMM).

According to one aspect of the present invention, the reception restriction system and the user terminal generate secret keys while exchanging random values with each other, thereby making it possible to more securely restrict the reception of the contents.

According to another aspect of the present invention, in the process of generating the secret key, the reception restriction system and the user terminal mutually authenticate each other, so that the secret key is generated more securely from the external hacking.

According to another aspect of the present invention, a step of generating an EMM (Entitlement Management Message) can be simplified by using a secret key generated each time the user terminal is booted, and the encryption / .

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when a part is referred to as being "connected" to another part, it includes not only "directly connected" but also "electrically connected" with another part in between . Also, when an element is referred to as "comprising ", it means that it can include other elements as well, without departing from the other elements unless specifically stated otherwise.

As used herein, the term " terminal random value " means any value randomly generated in a user terminal, and refers to a value used to generate a secret key in the user terminal and the reception restriction system. The term " terminal secret value " used herein is a secret value owned by each user terminal, and is a value used when providing the terminal random value to the reception restriction system.

As used herein, the term " server random value " refers to any value randomly generated in the reception restriction system, and the server random value is used by the reception restriction system and the user terminal to generate the secret key. As used herein, the " server secret value " is a secret value possessed by the reception restriction system, and is a value used when providing the server random value to the user terminal.

The " first secret key generation information " used herein is information generated in the user terminal and provided to the reception restriction system, and refers to information required by the reception restriction system to generate the secret key. The first secret key generation information may include, for example, a terminal random value and a terminal secret value. The " second secret key generation information " is information generated by the reception restriction system and provided to the user terminal, and refers to information that the user terminal needs to generate the secret key. The second secret key generation information may include, for example, a server random value and a server secret value.

Hereinafter, an overall configuration of an IPTV broadcasting service system according to an embodiment of the present invention will be described.

1 is an overall configuration diagram of an IPTV broadcast service system according to an embodiment of the present invention.

1, an IPTV broadcasting service system according to an exemplary embodiment of the present invention includes a broadcasting company 1000, a head end system 2000, a network 3000, and a user terminal 4000.

The headend system 2000 also includes a baseband system 2100, a compression multiplexing system 2200, a conditional access system (CAS) 2300, a back office system 2400, a monitoring system 2500, A Media Management Core (MOC) 2600, a subscriber management system 2700, a data broadcasting system 2800, and a return path server system 2900.

The broadcasting company 1000 plays a role of producing, editing, and modifying the content and providing it to the head end system 2000. Broadcasting company 1000 may include a program provider (PP), terrestrial or content provider (CP). In addition, the content provided by the broadcasting company 1000 may include existing content and rich content on the Internet.

The headend system 2000 receives and manages contents from the broadcasting company 1000 and distributes the contents to the user terminal 4000 to provide a broadcasting / recording / reproducing service. The received content may include related additional information and an EPG for such additional information.

The headend system 2000 transmits EPG information (PSIP / PSI / PSTN) including broadcast video and audio signals, data for data broadcasting, and program recommendation service menu via a subscriber aggregation device, a subscriber switch, and the like via a router supporting a multicast routing protocol. SI information) can be multicasted to a plurality of subscribers' IP set-top boxes.

The baseband system 2100 receives an MPEG2 broadcast signal or an analog broadcast signal from a terrestrial wave from an external program provider (PP), converts the received source broadcast signal to an SDI (Serial Digital Interface) signal, And distributes broadcasting video and audio signals of a plurality of broadcasting channels (for example, 100 channels) through a routine switcher. The broadcasting video and audio signals are distributed to a subtitle generator CG and an automatic program controller APC (Signal editing and processing) to the compression multiplexing system 2200 by inserting at least one of an advertisement, a logo, and a subtitle into the broadcast video and audio signal.

The SDI (Serial Digital Interface) signal is, for example, a digital signal standard having a transmission rate of 270 Mbps, and a composite digital image and four channels of digital audio signals may be mixed.

The baseband system 2100 basically comprises a receiving device (e.g., a DS-3 terminal, a Yagi antenna, a tuner for receiving an analog broadcast signal in an IRD) receiving a broadcasting signal such as a program provider A frame synchronizer for converting and correcting the source signal received from the receiving device into an SDI signal and synchronizing the frames, a frame synchronizer for connecting / concentrating all the broadcasting signal channels for operation management, / V router, and a character generator for editing and processing signals by inserting advertisements, logos, and subtitles into the SDI signal.

The compression multiplexing system 2200 multiplexes broadcast video and audio signals (Video, Audio) received from the baseband system 2100 into A / V encoders (for example, ) To compress an SDI (Serial Digital Interface) video signal to H.264, compress the audio signal to MPEG-2 AAC to generate an MPEG-2 TS (Transport Stream) -2 TS signal, data for broadcasting and EPG information (PSIP / PSI / SI information) generated by a data encoder and a PSI / SI generator (PSI / SI Generator) are multiplexed, When a reception restriction technique is used, the MPEG-2 TS signal is input to a scrambler to be encrypted, and finally, IP packetization is performed to transmit a TS (Transport Stream) broadcast signal.

Optionally, a receive restriction system 2300 can also be used to prevent illegal viewing and piracy of program recommended content.

The reception restriction system 2300 performs encryption for the real-time channel and pre-encrypts the VOD contents and controls the viewing authority. In addition, the reception restriction system 2300 generates a secret key while exchanging a random value with the user terminal 4000, and generates an EMM (Entitlement Management Message) using the generated secret key. The detailed configuration of the reception restriction system 2300 will be described later.

The back office system 2400 is a provisioning system and provides a billing function for use of the IPTV program service for each subscriber.

The monitoring system 2500 is a control system that can monitor the reception failure and the caption confirmation by monitoring the transmission failure of the A / V broadcasting signal for the IPTV broadcasting and the downlink of the IPTV head end system.

The media management system 2600 is a system for managing various business process information (program organization information, material information, contract information, product information, and the like) for operating the broadcasting service. The media management system 2600 integrally manages the information flow through the organic combination with each system at the center of the broadcasting center.

The media management system 2600 manages broadcast program information, content and media management information, contract information of program providers (PP) and content providers (CP), and product information, And can act as a coordinator for integrated management of information flow through organic combination.

In addition, the media management system 2600 is capable of real-time broadcasting and VOD (video-on-demand) broadcasting in terms of contract management, media and content meta data management, EPG information acquisition / management, Provides marketing management and reporting of marketing activities such as settlement with CP / CA and propensity to subscribers, analysis management, channel management, agent management, VOD catalog creation management and various merchandise management. Side video broadcast monitoring, video server transmission management, VOD subscriber authentication, recording / management of transmission result for settlement with CP / CA, and data synchronization with each linked subsystem.

The subscriber management system 2700 provides subscription and termination for the IPTV service, and member information management functions.

The data broadcasting system 2800 authorizes, verifies, prepares, and transmits the data for data broadcasting.

The data broadcasting system 2800 includes a data agent manager for managing data encoding, a PSI / SI generator PSI for generating program specific information / SI (Service Information) A data server / data encoder for encoding data broadcasting data into broadcast video and audio signals, a multiplexer manager (multiplexer / multiplexer) for managing the multiplexing function of data in the broadcast video and audio signals, Manager), and a scheduler UI (Scheduler UI).

In addition, the data broadcasting system 2800 may convert A / V data provided from an A / V server to an A / V encoder according to a terrestrial ACAP (Application Configuration Access Protocol) And compresses the compressed video and audio signals by an authoring tool into a data server / data encoder and a program specific information / service (PSI / SI) Information generator and EPG information (PSIP / SI information), which are multiplexed by a multiplexer, so that data broadcasting programs can be encoded and transmitted from the collection and storage of broadcasting program data and related information have.

The return path server system 2900 processes bi-directional data by a data provider (DP), provides online billing from the user terminal 4000, provides bidirectional data usage / billing interlock processing, , And bidirectional data for the program recommendation service, and transmits the corresponding response data to the user terminal 4000 through unicasting.

The network 3000 receives content from the headend system 2000 and transmits the received content to the user terminal 4000. The network 3000 includes a backbone network and an access network. The access network includes Ethernet, xDSL (ADSL, VDSL), HFC (Hybrid Fiber Coaxial Ca), FTTC Curb, and FTTH (Fiber To The Home) structures.

The user terminal 4000 generates a secret key while exchanging a random value with the reception restriction system 2300 and generates a control word from an Entitlement Management Message (EMM) and an Entitlement Control Message (ECM) Extracts the encryption key of the extracted CW, acquires the CW using the extracted encryption key of the CW, and discrambles the content.

Meanwhile, the user terminal 4000 is an apparatus for using an Internet broadcasting service, and generally includes an IPTV, a set-top box (STB), and a remote controller. The IPTV outputs the content received from the headend system 2000 and delivers the user response signal received through the remote controller to the headend system 2000 through the return channel of the settop box. The user terminal 4000 may use either a TV having an IP STB or an IP STB connected to the user's TV, a computer, a notebook, or a personal portable terminal.

Hereinafter, a detailed configuration of the reception restriction system 2300 according to an embodiment of the present invention will be described with reference to FIG.

2 is a detailed configuration diagram of a reception restriction system 2300 according to an embodiment of the present invention.

2, the reception restriction system 2300 according to an exemplary embodiment of the present invention includes an authentication processing unit 2310, a terminal random value extractor 2320, a server random value generator 2330, A secret key encryption unit 2350, a second secret key generation information generation unit 2360, and a content encryption unit 2370. The content encryption unit 2370 includes a CW generation module 2371, a scrambling module 2372, an ECM generation module 2373, and an EMM generation module 2374.

The authentication processing unit 2310 receives the certificate including the terminal secret value from the user terminal 4000 and authenticates the user terminal 4000. The authentication processing unit 2310 extracts the terminal secret value included in the certificate and transmits the terminal secret value to the terminal random value extractor 2320 to provide. The authentication processing unit 2310 also provides its own certificate including the server secret value to the user terminal 4000 so that the user terminal 4000 can authenticate the reception restriction system 2300. [

The authentication processing unit 2310 exchanges certificates with the user terminal 4000 in order to generate the secret key, so that the authentication processing unit 2310 is safer from the external hacking that may occur in the secret key generation process.

The terminal random value extractor 2320 receives the first secret key generation information including the terminal random value and the terminal secret value from the user terminal 4000 and extracts the terminal random value from the received first secret key generation information .

The terminal random value extractor 2320 extracts the terminal random value using the terminal secret value received from the authentication processing unit 2310 as the first secret key generation information Can be extracted. Also, the terminal random value extractor 2320 provides the extracted terminal random value to the secret key generator 2340.

The server random value generator 2330 generates a server random value used for secret key generation and provides the generated server random value to the secret key generator 2340 and the second secret key generation information generator 2360 . The server random value generator 2330 can update the server random value whenever the user terminal 4000 is powered on or whenever the authentication processing unit 2310 performs valid authentication.

The secret key generation unit 2340 generates a secret key using the extracted terminal random value and the generated server random value. Since the terminal random value used for generating the secret key is updated each time the user terminal 4000 is booted, the security of the secret key is further strengthened.

The secret key encryption unit 2350 encrypts the generated secret key using the generated secret key, and provides the encrypted secret key to the user terminal 4000. The encrypted secret key provided to the user terminal 4000 may be used to examine the validity of the secret key generated in the user terminal 4000 by comparing the secret key generated by the user terminal 4000 to be described later. Meanwhile, the secret key encryption unit 2350 may encrypt the ID information of the user terminal 4000 and the reception restriction system 2300 using the generated secret key, and may provide the encrypted ID information to the user terminal 4000 And the encrypted ID information can be used to examine the validity of the secret key generated in the user terminal 4000. [

The second secret key generation information generation unit 2360 generates second secret key generation information by combining the server random value and the server secret value, and provides the generated second secret key generation information to the user terminal 4000. The server secret value may be a value preset in the reception restriction system 2300, and the second secret key generation information generation unit 2360 may combine the server random value and the server secret value according to a predetermined algorithm. Also, the generated second secret key generation information may be used to generate a secret key in the user terminal 4000. Accordingly, the reception restriction system 2300 exchanges random values with each other with the user terminal 4000, and generates secret keys using the exchanged random values, thereby further enhancing the security of the contents.

The content encryption unit 2370 generates a CW to encrypt the content, generates an ECM and an EMM, and provides the encrypted content, the ECM, and the EMM to the user terminal 4000.

The CW generation module 2371 generates a CW for scrambling the content provided from the broadcasting company 1000 and the scrambling module 2372 scrambles the content provided from the broadcasting company 1000 using CW.

The ECM generation module 2373 receives the CW from the CW generation module 2371, and encrypts the received CW to generate an ECM including the channel / program-specific reception entitlement information.

The EMM generation module 2374 encrypts the ECM encryption key (the key used to encrypt the ECM) using the secret key generated by the secret key generation unit 2340 to generate the EMM. The EMM generation module 2374 can generate an EMM including the encryption key of the ECM and the viewing entitlement information for each subscriber in association with the subscriber management system 2700 that manages subscriber-specific entitlement management.

The EMM generation module 2374 generates the EMM using the secret key generated based on the terminal random value and the server random value updated every time the user terminal 4000 is booted so that the security of the EMM is further strengthened.

Also, since the EMM generation module 2374 generates the EMM using the secret key based on the random value updated at every boot without using the fixed key included in the smart card installed in the user terminal 4000, Even if the secret key is not encrypted again, it is possible to prepare for external hacking sufficiently, thereby simplifying the encryption process of the content.

Hereinafter, a detailed configuration of the user terminal 4000 according to an embodiment of the present invention will be described with reference to FIG.

3 is a detailed configuration diagram of a user terminal 4000 according to an embodiment of the present invention.

3, a user terminal 4000 according to an exemplary embodiment of the present invention includes a terminal random value generator 4010, a first secret key generation information generator 4020, an authentication processor 4030, A random value extracting unit 4040, a secret key generating unit 4050, a secret key validity determining unit 4060, and a content decrypting unit 4070. The content decryption unit 4070 includes an EMM decryption module 4071, an ECM decryption module 4072, and a descrambling module 4073.

The terminal random value generation unit 4010 generates a random value of the terminal and provides the generated terminal random value to the first secret key generation information generation unit 4020 and the secret key generation unit 4050. The generated terminal random value can be used to generate the secret key in the user terminal 4000 and the reception restriction system 2300 as described above.

In addition, the terminal random value generator 4010 can update and generate the terminal random value each time the user terminal 4000 is powered on. Since the terminal random value generator 4010 can update and generate the terminal random value used for generating the secret key whenever the user terminal 4000 is powered on, the security of the generated secret key can be further enhanced have.

The first secret-key-generation-information generating unit 4020 generates first secret-key generation information by combining the terminal secret value with the terminal secret value, and provides the generated first secret-key generation information to the reception limiting system 2300 . The terminal secret value may be a fixed value preset in the user terminal 4000 and the second secret key generation information generator 2360 may combine the terminal random value and the terminal secret value according to a predetermined algorithm. Also, the first secret key generation information may be used to generate the secret key in the reception restriction system 2300. [

The authentication processing unit 4030 receives the certificate including the server secret value from the reception restriction system 2300 to authenticate the reception restriction system 2300 and extracts the server secret value included in the certificate and outputs the server random value to the server random value extraction unit 4040 ).

In addition, the authentication processing unit 4030 provides the certificate of the user terminal 4000 to the reception restriction system 2300. The certificate provided by the authentication processing unit 4030 to the reception restriction system 2300 may include the terminal secret value.

Since the user terminal 4000 and the reception restriction system 2300 authenticate each other before exchanging the random values of each other used for generating the secret key, it is possible to generate the secret key more securely from the external hacking.

The server random value extractor 4040 receives the second secret key generation information from the reception restriction system 2300, extracts the server random value from the received second secret key generation information, and provides it to the secret key generation unit 4050 do. The server random value extractor 4040 extracts the server random value using the server secret value received from the authentication processing unit 4030, Can be extracted.

The secret key generation unit 4050 generates the secret key using the terminal random value and the server random value. The secret key generation unit 4050 can generate the secret key based on a predetermined algorithm using the terminal random value and the server random value. The terminal random value and the random value used for generating the secret key can be updated and generated every time the user terminal 4000 is powered on, so that the security of the generated secret key can be further strengthened.

The secret key validity determination unit 4060 receives the encrypted secret key from the reception restriction system 2300 and decrypts the encrypted secret key using the secret key generated by the secret key generation unit 4050, Key to the secret key generated by the secret-key generation unit 4050, and determines whether or not the secret-key generated by the secret-key generation unit 4050 is valid.

The content decryption unit 4070 receives the encrypted content, the ECM, and the EMM from the user terminal 4000, acquires the CW using the secret key, and descrambles the encrypted content using the CW.

The EMM decryption module 4071 extracts the encryption key of the ECM from the EMM received from the reception restriction system 2300 using the secret key generated by the secret key generation unit 4050. The ECM decryption module 4072 decrypts the ECM The CW is obtained from the ECM using the encryption key of the ECM.

The descrambling module 4073 descrambles the content using CW. The descrambling module 4073 compares the CP included in the ECM with the AP included in the EMM, and descrambles the content when it is judged to have a legitimate right.

According to the reception restriction system 2300 and the user terminal 4000 according to the embodiment of the present invention, the secret key is generated using the terminal random value and the server random value, which are updated each time the user terminal 4000 is booted, Since the EMM is generated using the generated secret key and the EMM is decrypted without using the fixed key of the smart card, the security of the content can be further enhanced while simplifying the decryption process of the content.

Hereinafter, a method of generating a secret key of the reception restriction system 2300 and the user terminal 4000 according to an embodiment of the present invention will be described with reference to FIG.

4 is a detailed flowchart illustrating a method of generating a secret key of a user terminal 4000 according to an embodiment of the present invention.

First, symbols and terms used in the description of the secret key generation method of FIG. 4 will be described.

ID_SUBS, ID_HE: ID of user terminal 4000 / reception restriction system 2300

C_SUBS, C_HE: The certificate of the user terminal 4000 / reception restriction system 2300

x_SUBS, x_HE: terminal secret value / server secret value

r_SUBS, r_HE: Terminal random value / Server random value

k: secret key

f (k, M) is an encryption function for message M using secret key k.

In operation S400, the user terminal 4000 generates a terminal random value, and in operation S402, the first secret key generation information is generated using the generated terminal random value. The user terminal 4000 can update and generate the terminal random value every time the power is turned on and combines the terminal random value r_SUBS and the terminal secret value x_SUBS based on the preset function to generate the first secret key generation information Lt; / RTI > The user terminal 4000 may generate the first secret key generation information, for example, a ^ (r_SUBS + x_SUBS). Further, the a value may be known to both the user terminal 4000 and the reception restriction system 2300.

Step S404 is a step in which the user terminal 4000 provides the first secret key generation information and the certificate of the user terminal 4000 to the reception restriction system 2300. [ The user terminal 4000 may provide a value (e.g., a ^ (r_SUBS + x_SUBS), C_SUBS) to the reception restriction system 2300 {user terminal 4000-> reception restriction system 2300) a ^ (r_SUBS + x_SUBS), C_SUBS}.

The terminal secret value may be included in the certificate of the user terminal 4000 and the terminal secret value may be used by the reception restriction system 2300 to extract the terminal random value from the first secret key generation information.

Step S406 is a step of authenticating the user terminal 4000 based on the certificate of the user terminal 4000 received by the reception restriction system 2300. Step S408 is a step of authenticating the terminal 4000 included in the certificate received by the reception restriction system 2300, And extracting the terminal random value r_SUBS from the first secret key generation information a ^ (r_SUBS + x_SUBS) using the secret value. The reception restriction system 2300 can extract the terminal random value only when the authentication is valid. Since the reception restriction system 2300 authenticates the user terminal 4000 when extracting the terminal random value received from the user terminal 4000, it is safer from the external hacking that may occur in the process of receiving the terminal random value .

Step S410 is a step in which the reception restriction system 2300 generates a server random value r_HE. The reception limiting system 2300 can update the server random value every time the authentication is valid corresponding to the terminal random value updated each time the user terminal 4000 is powered on.

Step S412 is a step in which the reception restriction system 2300 generates the secret key k using the terminal random value r_SUBS and the server random value r_HE, and encrypts the generated secret key. The reception limiting system 2300 may generate a secret key, for example, k = a ^ (r_SUBS * r_HE) mod N, by combining the terminal random value and the server random value based on a predetermined algorithm. The a value may be known to both the user terminal 4000 and the reception restriction system 2300. Also, the reception limiting system 2300 can encrypt the secret key itself using the generated secret key, for example, f (k, k). The encrypted secret key may be provided to the user terminal 4000 and used to determine the validity of the secret key generated at the user terminal 4000. Also, the reception restriction system 2300 encrypts the ID information with a secret key, for example, f (k, [ID_SUBS, ID_HE]) and provides the encrypted ID information to the user terminal 4000, (4000), the validity of the secret key can be determined.

Step S414 is a step in which the reception restriction system 2300 generates the second secret key generation information by combining the server random value r_HE and the server secret value x_HE. The receive restriction system 2300 may generate second secret key generation information, for example, a ^ (r_HE + x_HE).

Step S416 is a step for the reception restriction system 2300 to provide the encrypted secret key, the second secret key generation information and the certificate (C_HE) of the reception restriction system 2300 to the user terminal 4000 (the reception restriction system 2300 ) -> user terminal 4000: a ^ (r_HE + x_HE), C_HE, f (k, k)}. The certificate of the reception restriction system 2300 may include a server secret value used for extracting a server random value from the second secret key generation information. On the other hand, the reception restriction system 2300 may provide the encrypted ID information (e.g., f (k, [ID_SUBS, ID_HE]) to the user terminal 4000.

Step S418 is a step of authenticating the reception restriction system 2300 based on the certificate of the reception restriction system 2300 received by the user terminal 4000. Step S420 is a step of authenticating the reception restriction system 2300 based on the server included in the certificate received by the user terminal 4000 And extracting a server random value from the second secret key generation information using the secret value. Since the user terminal 4000 can extract the server random value received from the reception limiting system 2300 only when the authentication is valid, the user terminal 4000 is safer from the external hacking that may occur in the process of receiving the server random value.

Step S422 is a step in which the user terminal 4000 generates the secret key using the terminal random value and the server random value. The user terminal 4000 generates a secret key as in step S412, for example, k = a ^ (r_SUBS * r_HE) mod N by combining the terminal random value and the server random value based on a predetermined algorithm, for example can do.

Step S424 is a step for the user terminal 4000 to determine the validity of the generated secret key. The user terminal 4000 decrypts the encrypted secret key {e.g., f (k, k)} received from the reception restriction system 2300 using the generated secret key, and transmits the generated secret key and the decrypted It is possible to determine whether or not the generated secret key is valid by comparing the secret key. Also, the user terminal 4000 decrypts the encrypted ID information (for example, f (k, [ID_SUBS, ID_HE]) received from the reception restriction system 2300 using the generated secret key, The validity of the generated secret key can be judged.

According to the secret key generation method according to an embodiment of the present invention, the reception restriction system 2300 and the user terminal 4000 authenticate each other for generating a secret key, and are updated each time the user terminal 4000 is booted Since the secret key is generated using the terminal random value and the server random value, the security in the secret key generation process can be further strengthened.

Hereinafter, a reception limiting method according to an embodiment of the present invention will be described with reference to FIG.

5 is a detailed flowchart illustrating a reception restriction method according to an embodiment of the present invention.

First, the reception restriction system 2300 generates a CW, scrambles the content using the generated CW (S500), and provides the scrambled contents to the user terminal 4000 (S502).

Thereafter, the reception restriction system 2300 encrypts the CW to generate an ECM (S504), and provides the generated ECM to the user terminal 4000 (S506). The ECM may include an encrypted CW and a control parameter (CP).

Then, the reception restriction system 2300 generates an EMM using the secret key generated using the first secret key generation information (S508), and provides the generated EMM to the user terminal 4000. [ The reception restriction system 2300 can encrypt the encryption key of the CW with a secret key and generate an EMM including an Authorization Parameter (AP). The reception restriction system 2300 encrypts the encryption key of the CW using the secret key generated using the random value generated by the user terminal 4000 and the reception restriction system 2300, .

Then, the user terminal 4000 acquires the encryption key of the CW from the EMM using the secret key generated using the second secret key generation information (S512).

Then, the user terminal 4000 acquires CW using the encryption key of the CW (S514), and descrambles the scrambled content using the CW (S516).

Since the secret key used to obtain the encryption key of the CW from the EMM is generated using the random value updated every time the user terminal 4000 is booted as described above, the security of the content can be further enhanced.

In addition, since the user terminal 4000 does not use the fixed key value in the smart card in order to obtain the encryption key of the CW from the EMM, it is possible to simplify the content decryption step and enhance the security.

One embodiment of the present invention may also be embodied in the form of a recording medium including instructions executable by a computer, such as program modules, being executed by a computer. Computer readable media can be any available media that can be accessed by a computer and includes both volatile and nonvolatile media, removable and non-removable media. In addition, the computer-readable medium may include both computer storage media and communication media. Computer storage media includes both volatile and nonvolatile, 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. Communication media typically includes any information delivery media, including computer readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave, or other transport mechanism.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

1 is an overall configuration diagram of an IPTV broadcast service system according to an embodiment of the present invention;

2 is a detailed configuration diagram of a receive restriction system 2300 according to one embodiment of the present invention.

3 is a detailed configuration diagram of a user terminal 4000 according to an embodiment of the present invention.

4 is a detailed flowchart illustrating a method of generating a secret key of a user terminal 4000 according to an embodiment of the present invention.

5 is a detailed flow diagram illustrating a method of restricting reception according to an embodiment of the present invention.

DESCRIPTION OF REFERENCE NUMERALS

1000: Broadcaster 2000: Headend system

2300: reception restriction system 3000: network network

4000: User terminal

Claims (20)

A method for restricting reception through exchange of random values, Receiving first secret key generation information including a terminal random value generated in the user terminal from a user terminal, Generating a server random value of the reception limiting system, Generating a secret key using the terminal random value and the generated server random value; Generating second secret key generation information including the server random value and providing the second secret key generation information to the user terminal / RTI > The second secret key generation information is used for generating a secret key used for decrypting the EMM, Receiving the certificate of the user terminal from the user terminal and authenticating the user terminal, The terminal random value is extracted when the authentication is valid, Wherein the first secret key generation information includes a combination of the terminal random value and the secret value of the user terminal, the certificate received from the user terminal includes a secret value of the user terminal, And extracting from the first secret-key generation information using a secret value included in the certificate. delete delete A method for restricting reception through exchange of random values, Receiving first secret key generation information including a terminal random value generated in the user terminal from a user terminal, Generating a server random value of the reception limiting system, Generating a secret key using the terminal random value and the generated server random value; Generating second secret key generation information including the server random value and providing the second secret key generation information to the user terminal, The second secret key generation information is used for generating a secret key used for decrypting the EMM, Further comprising providing a certificate to the user terminal including a secret value of the reception restriction system, Wherein the second secret key generation information includes a combination of the server random value and the secret value of the reception restriction system, the provided certificate is used by the user terminal to authenticate the reception restriction system, Wherein the secret value included is used by the user terminal to extract the server random value from the second secret key generation information. A method for restricting reception through exchange of random values, Receiving first secret key generation information including a terminal random value generated in the user terminal from a user terminal, Generating a server random value of the reception limiting system, Generating a secret key using the terminal random value and the generated server random value, Generating second secret key generation information including the server random value and providing the second secret key generation information to the user terminal; And authenticating the user terminal by receiving the certificate of the user terminal from the user terminal, The second secret key generation information is used for generating a secret key used for decrypting the entitlement management message (EMM) If the authentication is valid, the terminal random value is extracted, Encrypting the generated secret key with the generated secret key, and providing the encrypted secret key to the user terminal, Wherein the encrypted secret key is decrypted using a secret key generated in the user terminal and compared with a secret key generated in the user terminal. A method for restricting reception through exchange of random values, Receiving first secret key generation information including a terminal random value generated in the user terminal from a user terminal, Generating a server random value of the reception limiting system, Generating a secret key using the terminal random value and the generated server random value, Generating second secret key generation information including the server random value and providing the second secret key generation information to the user terminal; And authenticating the user terminal by receiving the certificate of the user terminal from the user terminal, The second secret key generation information is used for generating a secret key used for decrypting the entitlement management message (EMM) The terminal random value is extracted when the authentication is valid, Wherein the terminal random value is generated by updating each time the user terminal is powered on. A method for restricting reception through exchange of random values, Receiving first secret key generation information including a terminal random value generated in the user terminal from a user terminal, Generating a server random value of the reception limiting system, Generating a secret key using the terminal random value and the generated server random value, Generating second secret key generation information including the server random value and providing the second secret key generation information to the user terminal; And authenticating the user terminal by receiving the certificate of the user terminal from the user terminal, The second secret key generation information is used for generating a secret key used for decrypting the entitlement management message (EMM) The terminal random value is extracted when the authentication is valid, Wherein the step of generating the server random value updates and generates the server random value each time the authentication is performed. A method for restricting reception through exchange of random values, Receiving first secret key generation information including a terminal random value generated in the user terminal from a user terminal, Generating a server random value of the reception limiting system, Generating a secret key using the terminal random value and the generated server random value, Generating second secret key generation information including the server random value and providing the second secret key generation information to the user terminal; And authenticating the user terminal by receiving the certificate of the user terminal from the user terminal, The second secret key generation information is used for generating a secret key used for decrypting the entitlement management message (EMM) If the authentication is valid, the terminal random value is extracted, Generating an encrypted EMM using the secret key and providing the generated EMM to the user terminal. In a reception limiting system via exchange of random values, The method includes receiving first secret key generation information in which a secret value of the user terminal and a terminal random value generated in the user terminal are combined from the user terminal and extracting a terminal random value of the user terminal from the first secret key generation information Terminal random value extracting unit, A server random value generator for generating a random value of the reception limiting system, A secret key generator for generating a secret key using the extracted terminal random value and the generated server random value, Generating a second secret key generation information by combining the server random value and the secret value of the reception restriction system, and providing the second secret key generation information to the user terminal, / RTI > The second secret key generation information is provided to the user terminal and used for generating a secret key used for decryption of an EMM, Further comprising an authentication processing unit for receiving a certificate including the secret value of the user terminal from the user terminal and authenticating the user terminal, Wherein the secret value included in the certificate is used to extract the random value of the terminal from the first secret key generation information. delete 10. The method of claim 9, Wherein the authentication processing unit provides a certificate including the secret value of the reception restriction system to the user terminal, Wherein the secret value included in the provided certificate is used to extract the server random value from the second secret key generation information. 10. The method of claim 9, And a secret key encryption unit for encrypting the secret key using the secret key and providing the encrypted secret key to the user terminal, Wherein the encrypted secret key is decrypted using a secret key generated in the user terminal and compared with a secret key generated in the user terminal. 10. The method of claim 9, Wherein the terminal random value is generated by updating each time the user terminal is powered on. 10. The method of claim 9, Further comprising a content encryption unit for generating an entitlement management message (EMM) using the secret key and providing the generated entitlement management message to a user terminal, Wherein the entitlement management message provided to the user terminal is decrypted using the secret key generated by the user terminal. A user terminal for canceling a reception restriction of a content through exchange of a random value, A terminal random value generator for generating a random value of the user terminal, A first secret key generation information generating unit for generating first secret key generation information in which the terminal random value and the secret value of the user terminal are combined and providing the first secret key generation information to the reception restriction system, Receiving a second secret key generation information in which a secret value of the reception restriction system and a server random value generated in the reception restriction system are combined from the reception restriction system, A server random value extracting unit for extracting a value A secret key generation unit for generating a secret key using the extracted server random value and the generated terminal random value, / RTI > Wherein the first secret key generation information is provided to the reception restriction system and used for generating a secret key used for generating an entitlement management message (EMM). 16. The method of claim 15, Further comprising an authentication processing unit for receiving a certificate including the secret value of the reception restriction system from the reception restriction system and for authenticating the reception restriction system, Wherein the secret value included in the certificate is used to extract the server random value from the second secret key generation information. 17. The method of claim 16, Wherein the authentication processing unit provides a certificate including the secret value of the user terminal to the reception restriction system, Wherein the secret value included in the provided certificate is used to extract the random value of the terminal from the first secret-key generation information. 17. The method of claim 16, A secret key validity determining unit for receiving the encrypted secret key from the reception restriction system, decrypting the encrypted secret key with the generated secret key, and comparing the decrypted secret key with the secret key generated at the user terminal The user terminal. 17. The method of claim 16, Wherein the terminal random value or the server random value is generated by updating each time the user terminal is powered on. 17. The method of claim 16, Further comprising a content decryption unit for receiving an encrypted EMM message using the secret key generated in the reception restriction system and decrypting the received EMM message using the generated secret key, .

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