KR100696823B1 - Pseudo scrambling method in digital broadcasting system - Google Patents

Abstract

The present invention relates to a pseudo scrambling method in a digital broadcasting system, wherein a transmitting side generates an original PMT including video PID information and audio PID information for each program, and an audio PID for each program in the original PMT. Only information is extracted and scrambled as one channel, pseudo-scrambled with different audio PID information for the remaining programs, and one scrambled channel information and pseudo scrambled broadcast program information are transmitted to a receiving side, and the encryption authentication process fails. If the receiver is to receive the broadcast information based on the pseudo-scrambled broadcast program information, and if the encryption authentication is successful, the descrambled and descrambled audio PID information of each channel transmitted, and the descrambled channel audio PID Information on each channel PMT By application it is characterized in that one to be a normally-view program on the receiving side. According to the present invention, since scrambling is required for only one channel in a pseudo scrambling method, the transmitting and receiving sides are compared with the scrambling of both the audio PID information and the video PID information for each channel of the entire conventional program. Can significantly reduce the scrambling and descrambling load. This reduces the burden on the operator due to frequent scrambling and finally has a ripple effect of providing better quality broadcasting services to consumers.

Pseudo Scrambling, Video PID, Audio PID

Description

Pseudo scrambling method in digital broadcasting system {PSEUDO SCRAMBLING METHOD IN DIGITAL BROADCASTING SYSTEM}

1 is a block diagram showing the configuration of a conditional access system in a typical digital broadcasting system;

2 is a flowchart of a pseudo scrambling process in a digital broadcasting system according to an embodiment of the present invention;

3 is an exemplary diagram of PMT (Program Map Table) in which scrambling and descrambling are performed according to the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to digital broadcasting technology, and in particular, to a method of pseudo scrambling in a digital broadcasting system suitable for providing a scrambling and de-scrambling technique for minimizing the load on the transmitting server. It is about.

Digital broadcasting is gradually being activated due to the commercial advantages of broadcasting a much wider range of channels than digital channels, and various functions such as high image quality, sound, interactive services, and internet access.

Accordingly, the digital set-top box industry is growing mainly in the United States and Europe, and is showing high growth in the Middle East and Asia due to the introduction of the digital broadcasting.

Digital broadcasting is mainly led by pay-TV operators, and the set-top box market is directly purchased by pay-TV businesses. In terms of technology, digital set-top boxes are designed to digitally code analog content at the broadcasting station so that the broadcast signal can be viewed on a regular TV through a satellite or cable ground. .

However, since the above process requires complicated processing, a technical problem may be raised in order for a broadcaster to supply various broadcast services. This is a matter of broadcasting standards, and the standards currently adopted by the world's largest broadcasters are the European standard DVB (Digital Video Broadcasting) or the US Direct Dict TV's own DSS (Digital Satellite Service). Various criteria are defined.

In addition, a conditional access system for conditionally accessing a transport stream, i.e., a digital transport stream, that restricts reception so that only subscribers can receive in pay broadcasting, that is, CAS also currently supports Media-Guard, NDS, and Vias ( More than 10 companies are competing.

Such CAS refers to a conditional access device for a digital satellite broadcasting set-top box, and is responsible for a paid reception function of digital satellite broadcasting.

1 is a block diagram showing the configuration of such a CAS. CAS is a core system of broadcasting system for digital broadcasting pay service along with subscriber management system. This ensures that subscribers receive precisely and conveniently the services they want, protects their income by preventing illegal viewing, and provides various marketing materials such as subscriber's viewing propensity to enable viewer-oriented broadcasting. System.

Here, in order to transmit and receive only a specific satellite broadcast signal, that is, to protect digital broadcast content, a viewer may view broadcast content only by scrambling and transmitting MPEG packets with respect to a specific satellite broadcast signal and descrambling it in a receiver.

Scrambling scrambles the multimedia data to be transmitted in a predetermined rule so that the scrambled data cannot be viewed by a receiver without receiving permission. The scrambling uses a control word (CW) to transform a signal. Encryption is a method of protecting the control word transmitted with the scrambled signal to be sent to the receiver's decryptor. The transmitter and receiver must have the same secret key to ensure that the descrambling process is accurate. Can be performed. In the process of delivering such a secret key, a smart card is used to deliver the secret key to the user in order to increase security.

The entitlement control function encrypts a control word and transmits it to an entitlement control message (ECM) to the receiver. The entitlement control function is periodically transmitted for security, and a new control word is encrypted each time. In addition to the encrypted control word, the ECM includes control parameters, and all receivers can receive the transmitted ECM. Among them, the secret key in the smart card is compared with the control variable and the authentication variable of the receiver. Decode the control word using and descramble the received program using it.

The entitlement management function is to entitle or update the receiver. The entitlement management system generates and encrypts an Entitlement Management Message (EMM) and transmits it to the receiver through a transport stream (TS). . The EMM performs the function of entitlement or renewal in the smart card, which is the security device of the receiver, and the function of changing the pin code of the smart card.

Eligibility is delivered through the EMM. The sender must send the program's authentication key and eligibility to the legitimate recipient of the subscription. The authentication key is encrypted using the recipient's unique distribution key, and then the EMM is generated by the EMM generator along with the authentication variable, and then the digital signature is added to prevent the message from being tampered with. The receiver checks whether the EMM has been sent to itself, checks the digital signature, and goes through the EMM authentication process. If all is OK, the authentication key is decrypted using its own distribution key and stored in the storage with the authentication variable.

The receiving principle of the program is as follows. In the transmitter, if the receiver has already received the authentication variable and the authentication key through the EMM, the transmitter encrypts the control word using the authentication key and then generates an ECM including the control variable through the ECM generator. ECM adds digital signatures to prevent tampering with messages. The source program is controlled by a control variable and scrambled using the thrust of the pseudo random binary sequence (PRBS) and transmitted to the receiver.

The receiver performs the ECM authentication process by checking the digital signature to confirm that the contents of the ECM have been tampered with. If there is no error, the encrypted control word part is sent to the decryptor and the control variable is sent to the comparator. The comparator compares the stored authentication variable with the control variable to check if the condition is correct, and if the condition is correct, passes the authentication key to the decryptor to decrypt the control word. The decrypted control word is used to descramble the program using the output of the PRBS controlled by it.

However, the existing digital broadcasting system undergoing the scrambling and descrambling process has a problem that the load is increased in the scrambled server because it is a method of scrambling the program element (audio, video, etc.) or the entire program. In other words, if the broadcast program has three channels, the server burden is increased because scrambling is performed for each of the three video channels (Packet Identification) and Audio PID.

In addition, since scrambling itself is licensed, the more frequently you perform scrambling, the greater the economic burden (royalty, etc.), which naturally results in end users taking up.

The present invention is to overcome the above-mentioned problems and technical limitations of the prior art, and 'pseudo-scrambled' as if deliberately miss-matched and scrambled video PID and audio PID to be decoded. It is an object of the present invention to provide a pseudo scrambling method in a digital broadcasting system capable of minimizing a scrambling load by scrambling only an audio PID of each program and then descrambling only an audio PID.

According to a preferred embodiment of the present invention for achieving the above object, a broadcast program transmission method of a digital broadcasting system, comprising: generating an original PMT including video PID information and audio PID information for each program at a transmitting side; Extracting only the audio PID information of each program from the original PMT and scrambled as one channel, and performing pseudo scrambling with different audio PID information for the remaining programs, and the scrambled one channel information and the pseudo scrambling. Transmitting the received broadcast program information to the receiving side, receiving the broadcast information at the receiving side based on the pseudo scrambled broadcast program information when the encryption authentication process fails, and when the encryption authentication is successful, The scrambled transmission Descrambling the audio PID information for each channel, and applying the descrambled channel-specific audio PID information to the PMT for each channel so that the receiving side can normally watch a program. It provides a scrambling method.

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

2 is a flowchart of a pseudo scrambling process in a digital broadcasting system according to an exemplary embodiment of the present invention, and FIG. 3 is an exemplary diagram of PMT in which scrambling and descrambling are performed according to the present invention. Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 2 and 3.

First, in step S200 and step S202 of FIG. 2, an original PMT to be received is generated, and video PID information and audio PID information for each program are generated. For example, the original PMT may be divided into program No. 1, program No. 2, and program No. 3 for each channel, as shown on the left side of FIG. 3, and the program for each channel includes video PID information ( 401, 501, 601 and audio PID information 402, 502, 602 are included.

In this case, in FIG. 3, the number of programs per channel is limited to three. However, this is only for convenience of description, and it is possible to set a plurality of programs for each channel according to a system specification. If you grow up, you will easily know.

Meanwhile, in steps S204 and S206, scrambling and pseudo scrambling are performed according to the present embodiment.

In detail, in step S204, only actual audio PID information of each channel is extracted and scrambled into one channel. That is, as shown in the lower center of FIG. 3, only the audio PID information 402, 502, 602 of the program for each channel is extracted and scrambling. Since only one channel needs to be scrambled, the scrambling load on the transmitting side can be greatly reduced.

For the remaining channels, as shown in step S206, the audio PID information of each channel program is randomly mixed and changed into different audio PID information. This is called "doctor scrambling" in the present embodiment, and an exemplary drawing thereof is as shown in the upper center of FIG.

Pseudo scrambling according to the present embodiment is to be implemented by changing the audio PID information for each channel-specific program, but this should be understood as only one embodiment. For example, pseudo-scrambled processing may be performed by fixing the separate audio PID information not included in the original PMT without changing the mutual audio PID information to one value. That is, the audio PID information (for example, 777) including commercials may be inserted into the audio PID information of each channel program and transmitted. In this case, an unauthorized receiving user may watch only a video channel on another channel. You will hear the commercial voice and sound.

Due to this pseudo scrambling process, since the original video PID information and the audio PID information do not match with each channel program, a normal broadcast viewing in which the receiver side scrambles the same effect, that is, video information and audio information is matched with each other. It will be impossible.

On the other hand, as described above, when the scrambling for one channel and the pseudo scrambling for the other channel are completed, broadcast information is transmitted to the receiving side as in step S208.

The receiving side performs an encryption authentication process (S210). This encryption authentication process has already been sufficiently mentioned in the prior art, and a detailed description thereof will be omitted.

If the authentication fails as a result of the encryption authentication, the process proceeds to step S212 so that broadcast information is received on the receiving side with limited restriction. That is, as described above, because the broadcast program for each channel is pseudo scrambled (because the audio PID information is changed or a separate advertisement PID information is inserted), broadcast information cannot be received or an advertisement is output by voice. Partial viewing restrictions can be implemented.

If the encryption authentication is successful, the process proceeds to step S214 to descramble the scrambled and transmitted channel-specific audio PID information 402, 502, 602.

Finally, in step S216, the descrambled channel-specific audio PID information 402, 502, 602 is applied to the PMT for each channel so that the program can be normally viewed. That is, as can be seen from the received PMT information shown on the right side of FIG. 3, the corresponding audio PID information that has been descrambled is matched to the program for each channel. It can be seen that this is the same as the original original PMT information.

The embodiments of the present invention have been described in detail above, but the present invention is not limited to these embodiments, and various modifications may be made by those skilled in the art within the spirit and scope of the present invention described in the claims below.

According to the present invention, since scrambling is required for only one channel in a pseudo scrambling method, the transmitting and receiving sides are compared with the scrambling of both the audio PID information and the video PID information for each channel of the entire conventional program. Can significantly reduce the scrambling and descrambling load. This reduces the burden on the operator due to frequent scrambling and finally has a ripple effect of providing better quality broadcasting services to consumers.

Claims (4)

As a broadcast program transmission method of a digital broadcasting system, Generating an original PMT including video PID information and audio PID information for each program at a transmitting side; Extracting only the audio PID information of each program from the original PMT and scrambling as one channel; Performing pseudo scrambling with different audio PID information for the remaining programs; Transmitting the scrambled channel information and the pseudo scrambled broadcast program information to a receiver; When the encryption authentication process fails, receiving broadcast information at the receiving side based on the pseudo scrambled broadcast program information; Descrambling the scrambled and transmitted channel-specific audio PID information when encryption authentication is successful; Applying the descrambled channel-specific audio PID information to the PMT for each channel so that the receiving side can normally watch a program. Pseudo scrambling method of a digital broadcasting system comprising a. The method of claim 1, The pseudo scrambling is a method of pseudo scrambling of a digital broadcasting system, characterized in that the audio PID information for each program is randomly mixed and changed into different audio PID information. The method of claim 1, The pseudo scrambling is a method of pseudo scrambling of a digital broadcasting system, characterized in that the separate audio PID information not included in the original PMT is fixed to one value and applied to each program. The method of claim 1, Pseudo scrambling method of digital broadcasting system to partially limit the viewing when the encryption authentication process fails.

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