KR20070052120A - Broadcasting content protection system and method - Google Patents

Abstract

The present invention relates to a system and method for protecting broadcast content, receiving an original video in MPEG-2 TS format in the form of a streaming packet, and analyzing the received streaming packet to encrypt the video for each broadcasting channel in real time, and then multiplying the original video. A real time encryption server transmitting in a cast; A key issuing server that manages a key required to decrypt a protected video and transmits key information for decrypting encrypted media data to the protected video stream playback device when requesting key information from the protected video stream playback device; And a protected video stream reproducing apparatus that decodes the protected video stream transmitted in real time from the real time encryption server using the key information received from the key issuing server, thereby providing streaming service in a multicast manner. In the broadcast content protection system, even if the encryption key is frequently changed, the broadcast content can be protected without affecting the existing streaming system while minimizing the overload of the decryption key issuing server and the delay of the service.

MPEG-2 Transport Stream (TS), DRM, Streaming, Piracy, Content Protection

Description

Broadcast Content Protection System and Method {BROADCASTING CONTENT PROTECTION SYSTEM AND METHOD}

1 is a configuration diagram of an embodiment of a broadcast content protection system according to the present invention;

2 is a block diagram of a real-time encryption server according to the present invention,

3 is a block diagram of a key issuing server according to the present invention;

4 is a block diagram of a protected video stream playback device according to the present invention;

5 is a configuration diagram of a key table used in the present invention.

<Description of the symbols for the main parts of the drawings>

10: real time encryption server

20: key issuing server

30: protected video stream playback device

The present invention relates to a broadcast content protection system and method for streaming service, and more particularly, illegal storage and illegal storage of broadcast content in a broadcast service environment using multicast streaming of a video in MPEG-2 TS (Transport Stream) format. The present invention relates to a broadcast content protection system and method for preventing illegal use and distribution of content through duplication.

MPEG-2 is an image compression technology standardized by ISO 13818 in 1994. It is an improvement of MPEG-1 for video that requires high image quality and sound quality such as digital TV and DVD. MPEG-2 Transport Stream (TS) multiplexes the MPEG-2 system for streaming, and takes MPEG-2 data into a packet of a relatively small size of 188 bytes in consideration of errors on the network.

Since digital information is easy to produce and distribute, the production of digitized video is increasing. However, since digital contents are easily copied, transformed, and distributed, and distributed through the insecure Internet, security and copyright issues are emerging as important issues. This problem has occurred mainly in the video stored and played on the user's PC. In the past, in order to protect the video file stored in the user's PC, after encrypting the entire video file, the encrypted content is downloaded to the user's local system. For example, we used a method that provides information to decrypt only encrypted video files to legitimate users.

On the other hand, streaming is a technology that enables playback by transmitting data in real time without storing contents in the local system. In the case of large video content, it is common to provide services through streaming in the same manner as video on demand. to be. In general, although video played through a streaming service is not stored in the user's PC, the video played through a streaming service is solved to some extent, such as illegal copying. However, recently, video serviced through streaming can be stored. With the advent of the capture program, there is also a need to protect the video service through streaming. However, in the past, security measures mainly focused on user authentication using ID / PW were used to protect streaming videos. However, in the case of a protection method through encryption of contents, it was difficult to use universally as a method specialized in a specific streaming format.

The most common type of streaming scheme is unicast communication, which means that a single sender must repeatedly send the same data to each receiver in order to send data to multiple receivers, thereby wasting resources of the sender node and network bandwidth. Cause. IP multicast technology to solve this problem prevents duplicate data from occurring according to the data path (multicast data transmission path) between the multicast routers existing between the sender and the receiver. In order to use the IP multicast mechanism, receivers join a specific group through IGMP in advance, and the sender transmits data to the group address instead of each recipient's address. This data is copied and forwarded repeatedly until it arrives at all receivers in the group along the data path configured by the multicast routing protocol between IP multicast routers. The edge multicast router with the recipients who finally joined the group broadcasts the multicast data on its subnet. Through this process, the IP multicast mechanism is a method that can efficiently use both the resources of the transmitting node and the network bandwidth regardless of the number of receivers participating in the group.

A general method for protecting broadcast content that is multicast streamed uses a method of encrypting and transmitting a broadcast channel and issuing information to a user in a form of a license from a separate server whenever the broadcast channel is changed. However, when this method is used, if the encryption key used to encrypt the content is changed, a large number of users are brought to the license issuing server at once to receive the changed decryption key, which causes server overload and service delay. do. In addition, the content protection system should be able to be applied independently of the existing streaming server.

Therefore, in the protection system of broadcasting contents that are serviced by the multicast method, even if the encryption key is frequently changed, it can be easily applied without affecting the existing streaming system while minimizing the overload of the decryption key issuing server 20 or the delay of the service. There is an urgent need for measures to protect broadcast contents.

Accordingly, the present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a server that serves broadcast content to protect the content from illegal storage of broadcast content in a broadcast service environment using multicast streaming. The broadcast content that encrypts the streamed video in real time (generates a protected video stream) by applying encryption technology, and the client side who watches the broadcast decrypts the protected video stream in real time (plays the protected video stream). It is to provide a protection system and method.

Broadcast content protection system and method in a broadcast service environment using a video file of the MPEG-2 TS format of the present invention for achieving the above object, receives the original video of the MPEG-2 TS format in the form of a streaming packet, and receives A real-time encryption server 10 for analyzing one streaming packet and encrypting a video for each broadcasting channel in real time and transmitting the same again in multicast; A key issuing server that manages a key required to decrypt a protected video and transmits key information for decrypting encrypted media data to the protected video stream playback device 30 when a key issuance request from the protected video stream playback device is requested. 20; And a protected video stream reproducing apparatus 30 which decodes the protected type video transmitted by streaming from the real time encryption server 10 in real time using the key information received from the key issuing server 20. It is characterized by.

Hereinafter, a system and method for protecting broadcast content in a broadcast service environment using a file of a MPEG-2 TS format according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a configuration diagram of a broadcast content protection system according to an embodiment of the present invention, and shows the overall system configuration of a broadcast service while protecting broadcast content.

Referring to FIG. 1, the streaming server streams an MPEG-2 TS format video file or a video live stream input from a camera to the real time encryption server 10 using the original video multicast address for each broadcasting channel. In this case, the multicast address used refers to a multicast address previously internally negotiated between the streaming server and the real time encryption server 10 so that the streaming packet transmitted from the streaming server can be received only by the real time encryption server 10.

The real time encryption server 10 receives the streaming packet transmitted from the streaming server, classifies the streaming packet for each broadcasting channel, and encrypts the data in real time using the encryption key information. The encrypted streaming packet is retransmitted to the encrypted video multicast address for each broadcast channel. In this case, the multicast address used is an address used when a user watching a broadcast requests a broadcast service. A series of operations to interpret, encrypt, and retransmit streaming packets is performed at the kernel layer, not at the application layer. In addition, the real-time encryption server 10 transmits the key information and current time information used when encrypting to the key issuing server 20 to synchronize this information with the key issuing server 20, and if the key table is changed, the channel ID of the corresponding channel. And version information of the key table are transmitted to the content service server.

The key issuing server 20 manages key information transmitted from the real-time encryption server 10, and issues key information when a request for issuing key information necessary to decrypt a protected video is provided by the protected video stream reproducing apparatus 30. This is used to decode the video. In addition, when a time synchronization request is received from the protected video stream reproducing apparatus 30, the current time is transmitted to synchronize the current time of the key issuing server 20 and the protected video stream reproducing apparatus 30.

The content service server is a web server that a user accesses to receive a broadcast service. The web page provides a list of broadcast channels, broadcast schedules, and broadcast programs currently being serviced on a web page. When the user selects a broadcasting channel to watch on the web page, the content service server issues the channel ID, multicast address, channel information of the key table used to encrypt the channel, and issuing the key, which are information necessary for the user to receive the streaming service. The address of the server 20 and the like are transmitted to the protected video stream reproducing apparatus 30. Whenever this information is changed, the content service server can modify the web page and set it automatically or manage it automatically in the form of a database. Whenever the user selects a broadcasting channel, the content service server can extract the information on the channel and deliver it to the user. It does not define separately, such as using HTTP as a web protocol or using a separate method.

The protected video stream reproducing apparatus 30 accesses the encrypted video multicast address of the broadcast channel received from the content service server, receives the encrypted video stream transmitted from the real time encryption server 10, and receives the key issuing server 20. ) To request and receive key information about the channel. The encrypted video stream is decrypted in real time using the received key information, and the decrypted video stream is reproduced through a decoder.

In order to easily apply a content protection method to an existing broadcast content service system, the present invention has a structure in which a streaming server encrypts and retransmits the streaming packet in real time after the original content is streamed. Since encryption is performed after being sent from the streaming server, it can be applied independently of the existing streaming system. In addition, the real-time encryption server 10 encrypts and retransmits streaming packets in real time in the kernel layer, not in the application layer, thereby minimizing the delay time due to encryption, and since the data size after encryption is the same as before encryption, it does not affect the data bit rate.

2 is a block diagram of a real-time encryption server 10 according to the present invention. The real-time encryption server 10 of the present invention generates a base time required when calculating the key to be used for encryption, the time each key is used for encryption, and generates the generated key, the reference time, and information on changing period of the key. To generate the key table and the version information of the key table. Encrypted information generating unit 103; The encryption information generation unit 103 provides an interface for inputting a change cycle of the key table generated by the encryption information generator 103 and a change cycle of the keys included in the key table, and generates a key by checking the change cycle of the key table. A key table manager 104 for requesting 103; When the key table is newly generated, the changed key table and version information of the key table are transmitted to the key issuing server 20 so that the version information of the key table and the key table managed by the real-time encryption server 10 and the key issuing server 20 can be obtained. A key table synchronizing unit 102 for transmitting the version information of the key table to the content service server when the key table used for synchronization and encryption is changed and the version information of the key table is changed; A time synchronization unit 101 for periodically synchronizing the current time with the time synchronization unit 201 of the key issuing server 20 using the time synchronization protocol and sending the current time to the encryption information generation unit 103; The original video multicast address (IP and Port information) used to stream the original video from the streaming server with the information about the broadcast channel to be serviced, the encrypted video multicast address to use to send the encrypted video in multicast, and the channel ID. A channel information manager 105 which provides an interface for inputting information and manages input channel information; Receives the original streaming packet transmitted from the streaming server, encrypts the channel by classifying the streaming packet for each broadcasting channel by using the IP included in the streaming packet, the port information, the channel ID received from the channel information management unit 105, and the original video multicast address. A streaming packet analyzer 106 for transferring to the unit 107; And extracting a TS stream from the streaming packet received from the streaming packet analyzer 106, encrypting only the payload portion of the TS packet including the video data in units of TS packets, and then channel information management unit 105. It includes a channel encryption unit 107 for retransmitting in a multicast manner using the channel ID, the encrypted video multicast address received from.

The following is a process of encrypting a streaming packet received in real time encryption server 10 according to the present invention in real time. Processes A, B, C, D, and E are processes that must be executed before encrypting the streaming packet or be performed when an event occurs separately from the encryption process. Processes 1) to 6) are performed on the real-time encryption server 10. An encryption process is repeatedly performed whenever a packet of an original video is received.

A. In the channel information manager, the multicast address of the original video, the multicast address of the encrypted video, and the channel ID are input.

B. In the key table management unit 104, information on the change cycle of the key table and the change cycle of the key for each channel is input.

C. The time synchronizer 101 of the real time encryption server 10 transmits current time information to the time synchronizer 201 of the key issuing server 20 to periodically synchronize.

D. The key table synchronization unit 102 of the real-time encryption server 10 generates a current key table to be used for current encryption and a next key table to be used next in each channel, and issues the generated key table and version information of the key table. The key information management unit 203 of the server 20 is transmitted to synchronize the key issue server 20 with the key table information.

E. When the version of the key table to be used for current encryption is changed, the version information of the key table is transmitted to the content service server.

1) IP and Port information is extracted from the streaming packet of the original video received from the streaming server, and the streaming packet is classified into the corresponding channel by comparing with the original video multicast address among the channel information input in step A.

2) The TS stream is extracted from the classified streaming packets, and read from the TS stream in units of TS packets to find out whether the PID (Program ID) value is '0' to find TS packets containing PAT (Program Association Table) information. The next TS packet is read until a TS packet containing PAT information comes out. When the TS packet containing the PAT data is found, the PID value of the TS packet including the PMT (Program Map Table) information is extracted.

3) The next TS packet is read to find a TS packet having the PID of the PMT packet. The next TS packet is read until a TS packet containing the PMT information comes out. When the TS packet containing the PMT information is found, the PID value of the TS packet containing the video data and the PID value of the TS packet containing the audio data are extracted from the PMT.

4) Read the next TS packet and check if it is PID of TS packet that contains video or audio data. If it is a video or audio TS packet, only the payload part except the header of the TS packet is encrypted and the scrambling control bit value of the header is set to '11'. Do not encrypt video or audio TS packets.

5) The IP and Port information of the streaming packet is set to the encrypted video multicast address of the channel currently processed among the channel information input in step A, and the streaming packet is retransmitted in a multicast manner.

3 is a block diagram of a key issuing server 20 according to the present invention. The key issuing server 20 of the present invention periodically requests and receives the current time from the time synchronization unit 101 of the real-time encryption server 10 by using a time synchronization protocol, thereby real-time encryption server 10 and key issuing server 20. ) Synchronizes the current time and transmits the current time to the time synchronizer 301 of the protected video stream playback device 30 when the current time is requested from the protected video stream playback device 30. A time synchronizer 201; The key table, key table version information, and reference time information transmitted from the key table synchronization unit 102 of the real-time encryption server 10 are stored in the storage 204 (physical storage space such as hard disk and memory) for each broadcasting channel. A key information management unit 203 for managing; remind When a request for issuing a key for a specific channel is received from the protected video stream reproducing apparatus 30, the current time received from the time synchronization unit 201, the channel ID of the corresponding channel received from the key information management unit 203, and the key. And a key information generation unit 201 for generating key information using the table and reference time information and transmitting the generated key information to the protected video stream reproducing apparatus 30.

4 is a block diagram of a protected video stream reproducing apparatus 30 according to the present invention. The protected video stream reproducing apparatus 30 of the present invention turns on the power or periodically requests the time of the key synchronization server 201 of the key issuing server 20 using the time synchronization protocol at set time intervals. 20 synchronizes the current time of the protected video stream reproducing apparatus 30, and receives the key information from the key issuing server 20, and uses the current time information included therein to protect the video with the key issuing server 20. A time synchronization unit 301 for synchronizing the current time of the stream reproducing apparatus 30; A content service information processing unit 303 for receiving a multicast connection address of a broadcast channel, channel ID, key table version information, and a key issuing server 20 address, which are information required for viewing a broadcast channel from a content service server; Receiving a channel ID, key table version information, and a key issuing server 20 address from a content service server, whether the key information of the corresponding channel is stored in the storage 304 using the received channel ID, and the received current The version information of the key table is used to check whether the version information of the current key table stored in the storage 304 is matched, and the key issuing server 20 requests and receives the key information of the corresponding channel, and the key information is received. A key information processing unit 302 for storing in the storage 304; Receiving an encrypted video multicast address from the content service information processing unit 303, A streaming client 305 accessing an encrypted video multicast address of a corresponding channel to receive a multicast streaming packet, and then combine it into a TS stream; A packet decrypting unit (306) for decrypting the encrypted TS stream received from the streaming client in units of TS packets using key information received from the storage 304; A storage 304 for storing the unique identification information of the protected video stream playback device 30, the certificate, and the key information (channel ID, key table version information, key table, reference time) received from the key issuing server 20 Include. In the protected video stream reproducing apparatus 30, the storage 304 in which key information such as a key table, a reference time, and other information are stored may be a physical storage medium such as a memory, a hard disk, or a smart card.

The process of decrypting the encrypted streaming packet in the protected video stream reproducing apparatus 30 according to the present invention is as follows.

1) When the user device (PC or set-top box, etc.) in which the protected video stream playback device 30 is installed is turned on, the current time of the user device is requested by receiving and receiving the current time from the key issuing server 20 through a time synchronization protocol. Synchronizing;

2) selecting a broadcast channel to be watched by a user and receiving a multicast address, a channel ID, version information of the current key table, and an address of the key issuing server 20 from the content service server;

3) checking whether key information of the corresponding channel is stored in the storage 304 by using the received channel ID;

4) if key information of the corresponding channel is stored, checking whether the version information of the current key table received from the content service server and the version information of the key table stored in the storage 304 are the same;

5-a-1) If the key information for the corresponding channel is not stored or the version information of the key table does not match, accessing the address of the key issuing server 20 received from the content service server and requesting and receiving the key information is performed. step;

5-a-2) Extract the key information by checking whether the key information for the requested channel is correct using the channel ID from the key information received from the key issuing server 20 and whether it matches the version information of the key table to be used for decryption. Storing in the reservoir 304;

5-b) if the key information for the corresponding channel is stored and the version information of the key table matches, executing step 6);

6) accessing an encrypted video multicast address of a corresponding channel received from a content service server to receive a streaming packet and combine it into a TS stream;

7) checking a key application time of a key table and setting a key to be applied for decryption;

8) reading the TS stream in units of TS_packets and checking whether the scrambling control bit field value of the TS packet header is set to '11';

9-a) If the value of the scrambling control bit field is set to '11', the payload of the TS packet is decoded, the value of the scrambling control bit field is set to '00' again and the process is restarted from step 7) to process the next TS packet. Executing;

9-b) if the scrambling control bit field value is not set to '11', executing again from step 7) to process the next TS_packet without performing decryption;

It consists of.

In the process of decrypting the streaming packet of the protected video stream reproducing apparatus 30, a method of selecting a key to be used for decryption among the various keys in the key table and synchronizing the keys according to the time when the key is to be applied is as follows. Calculate the value of 'base time + key application time' in the index order in the current key table until the value is greater than the current time. If the value of 'reference time + key application time' is greater than the current time, the key of the index is set as the key to be used for current decryption and then decrypted. Each time the TS packet is decrypted, the time is compared. If the value of the 'reference time + key application time' becomes equal to the current time, the key corresponding to the next index is set as the decryption key.

while (TS packet) {

    // in current key table

    for (i = 0; i <max index value; i ++) {

        if (base time + key applied time [i]> current time) {

            Setting key [i] as a decryption key;

            break;

        }

        else continue;

    }

    if (if no key in the current key table satisfies the condition) {

        // in the following key table

        for (i = 0; i <max index value; i ++) {

            if (base time + key applied time [i]> current time) {

                Setting key [i] as a decryption key;

                break;

            }

            else continue;

        }

    }

    if (if no key in the next key table satisfies the condition) {

        return error;

    }

    Performing packet decryption;

    }

}

5 is a configuration diagram of a key table used in the present invention. The key information issued by the key issuing server 20 is Consists of channel ID, current time information, current key table version information, current key table, current key table reference time, next key table version information, next key table, next key table reference time do. The channel ID is used to confirm whether the information on the requested channel is correct, and the current time information is used to synchronize the current time of the protected video stream playback device 30 that has received the key information with the current time of the key issuing server 20. I use it. The version information of the key table is used to check whether the version of the key table to be used for decryption is correct and to check whether the key table for the corresponding broadcast channel is stored in the storage 304 when selecting a broadcast channel. The reference time information is used to calculate the time applied to decryption among the various keys included in the key table. The key information generated by the key issuing server 20 includes a next key table to be used next since it is a change cycle between a current key table to be used for decryption and a key table currently being used. In this way, when it is necessary to change the key table while watching a channel, it is possible to change to the next key table without the process of having to issue the key information again from the key issuing server 20. The key table constituting the key information is composed of an index, a key, and a key application time. In the key table, an index is a serial number of a key, a key is used for decryption, and a key application time is used to calculate a time when a key in the key table is applied during decryption together with a reference time. At this time, the key value to be used for decryption is changed according to the key application time.

Although the present invention has been described in detail with reference to some embodiments, the present invention is not necessarily limited to these embodiments, and various modifications can be made without departing from the spirit of the present invention.

As described above, a broadcast content protection system and method in a broadcast service environment using a video file of MPEG-2 TS format according to the present invention are existing in a broadcast service environment using multicast streaming transmission of a video of MPEG-2 TS format. Encrypts and protects only the payload of MPEG-2 TS packets without affecting the streaming server, and transmits the key information necessary to decrypt the transmitted video at once, and applies it when the client decrypts it by key synchronization. In order to receive the key information, there is an effect of solving the problem of concentrating the connection to the key issuing server 20 and the resulting server overload, and preventing the delay of the service.

In addition, by concentrating the connection to the key issuing server 20 and the resulting overload of the server for the key issuance request, it is possible to frequently change the key used to encrypt the video content, thereby increasing the security level of the content. .

In addition, the present invention can protect the video file while maintaining the existing streaming service environment as it is, there is an effect that can protect the copyright at a low cost.

Claims (12)

In a broadcast content protection system using multicast streaming of a video file in MPEG-2 TS format,  A real-time encryption server 10 which receives the original video in MPEG-2 TS format in the form of a streaming packet, analyzes the received streaming packet to encrypt the video for each broadcast channel in real time, and then transmits the video again in multicast; Manages a key required to decrypt the protected video, and transmits the key information for decrypting the encrypted media data to the protected video stream playback device 30 when a key issuance request from the protected video stream playback device 30 A key issuing server 20; And a protected video stream reproducing apparatus 30 which decodes the protected video in real time transmitted from the real time encryption server 10 in real time using the key information received from the key issuing server 20. A broadcast content protection system. The method of claim 1, The real-time encryption server 10 generates a base time required when calculating a key to be used for encryption and a time for each key to be used for encryption, and using the generated key, reference time, and key change period information, the key table is used. To generate version information for the key table with Encryption information generating unit 103; The encryption information generation unit 103 provides an interface for inputting a change cycle of the key table generated by the encryption information generator 103 and a change cycle of the keys included in the key table, and generates a key by checking the change cycle of the key table. A key table manager 104 for requesting 103; Synchronize the version information of the key table and the key table managed by the real-time encryption server 10 and the key issuing server 20 by transmitting the changed key table and version information of the key table to the key issuing server 20 when a new key table is generated. A key table synchronization unit 102 for transmitting the version information of the key table to the content service server when the key table used for encryption is changed and the version information of the key table is changed; A time synchronization unit 101 for periodically synchronizing the current time with the time synchronization unit 202 of the key issuing server 20 using the time synchronization protocol and sending the current time to the encryption information generation unit 103; The original video multicast address (IP and Port information) used to stream the original video from the streaming server with the information about the broadcast channel to be serviced, the encrypted video multicast address to use to send the encrypted video in multicast, and the channel ID. A channel information manager 105 which provides an interface for inputting information and manages input channel information; Receives the original streaming packet transmitted from the streaming server to separate the streaming packet by broadcasting channel by using the IP included in the streaming packet, the port information, the channel ID received from the channel information management unit 105, and the original video multicast address. Streaming packet analysis unit 106 to pass to the encryption unit 107; And extracting a TS stream from the streaming packet received from the streaming packet analyzer 106, encrypting only the payload portion of the TS packet including the video data in units of TS packets, and then channel information management unit 105. And a channel encryption unit (107) for retransmitting in a multicast manner using the channel ID and the encrypted video multicast address. The method according to claim 1 or 2, The key issuing server 20 periodically requests and receives the current time from the real-time encryption server 10 using the time synchronization protocol to synchronize the current time of the real-time encryption server 10 and the key issuing server 20 and is protected. When the current time request is received from the video stream player 30, the current time is transmitted. A time synchronizer 202; A key information manager 203 for managing a key table, key table version information, and reference time information transmitted from the real time encryption server 10 for each broadcast channel; When a request for issuing a key for a specific channel is received from the protected video stream playback device 30, the protected video stream playback device 30 is generated by generating key information using the current time, the channel ID of the corresponding channel, the key table, and the reference time information. And a key information generation unit (201) for transmitting to the broadcast content protection system. The method of claim 3, wherein The protected video stream reproducing apparatus 30 turns on the power or periodically requests the current time from the key issuing server 20 using the time synchronization protocol at a set time, thereby protecting the key issuing server 20 and the protected video stream reproducing apparatus. Synchronize the current time of the 30, and when the key information is received from the key issuing server 20, the current time of the key issuing server 20 and the protected video stream playback device 30 by using the current time information included therein A time synchronization unit 301 for synchronizing; A content service information processing unit 303 for receiving a multicast connection address of a broadcast channel, a channel ID, version information of a current key table, and an address of a key issuing server 20, which are information required for viewing a broadcast channel from a content service server; Check whether the key information of the corresponding channel is stored in the storage 304 using the channel ID, and whether the version information of the current key table stored in the storage 304 is consistent using the version information of the current key table, and the key issuing server A key information processing unit 302 for requesting and receiving key information of a corresponding channel from the 20 and storing the key information in the storage 304; A streaming client 305 accessing an encrypted video multicast address of a corresponding channel to receive a multicast streaming packet and combine it into a TS stream; A packet decryption unit 306 for decrypting a TS stream in units of TS packets using a key of a key table; And a storage (304) for storing the unique identification information of the protected video stream reproducing apparatus (30), the certificate, the key information received from the key issuing server (20), and the like. The method according to claim 1 or 4, It shows a list and information on the broadcast channel to the user, and adds a content service server for transmitting the information necessary for receiving the streaming service to the protected video stream playback device 30 when the user selects the desired broadcast channel Broadcast content protection system. A streaming packet classification step of receiving a streaming packet of an original video sent from a streaming server, extracting IP and port information from the received streaming packet, and classifying the streaming packet for each channel by comparing the original video multicast address; A PID detection step of extracting a TS stream from the classified streaming packets and classifying and detecting a PID of a PMT packet and a PID of a video and audio packet from the TS stream; Encrypting the detected PID by classifying the PID of the PMT packet and the PID of the video and audio packet; A streaming packet transmission step of setting IP and port information of the streaming packet to an encrypted video multicast address of a channel currently being processed and retransmitting streaming in a multicast manner; And a decryption processing step of accessing the encrypted multicast address to receive the streaming packet, classifying and decrypting the packet according to the scambling control bit field value of the TS packet header. The method of claim 6, The PID detection step extracts a TS stream from the classified streaming packets, reads the TS stream in units of TS packets, checks whether the PID (Program ID) value is '0', and stores TS packets containing PAT (Program Association Table) information. Find. The next TS packet is read until a TS packet containing PAT information comes out. When the TS packet containing the PAT data is found, the PID value of the TS packet including the program map table (PMT) information is extracted, and the next TS packet is read to find a TS packet having the PID of the PMT packet. The next TS packet is read until a TS packet containing the PMT information comes out. If the TS packet containing the PMT information is found, the PID value of the TS packet containing the video data and the PID value of the TS packet containing the audio data are extracted from the PMT. The method according to claim 6 or 7, The encryption process reads the next TS packet and checks whether it is the PID of the TS packet containing the video or audio data. If the video or audio TS packet, encrypts only the payload part except the header of the TS packet, sets the scrambling control bit value of the header to '11', and does not encrypt the video or audio TS packet. The method of claim 8, In the decryption processing step, access the encrypted video multicast address of the corresponding channel to receive streaming packets, combine them into TS streams, read them in TS packet units, and check whether the scrambling control bit field value of the TS packet header is set to '11'. If the scrambling control bit field value is not set to '11', decoding is not performed. If the scrambling control bit field value is set to '11', the payload of the TS packet is decoded and the scrambling control bit field value is set to '11'. And resetting to '00' and processing the next TS packet. The method according to claim 6 or 9, And requesting a content service server for content service information necessary for selecting a broadcast channel desired by the user after the encryption processing step, and setting a key information for using the content service information. The method of claim 10, The key information setting step uses the received channel ID to check whether the key information of the corresponding channel is stored in the storage 304 and whether the version information of the stored key table is the same as the received version information of the current key table. If the key information is not stored or the version information of the key table does not match, access the key issuing server 20 using the address of the received key issuing server 20 to request and receive the key information, and the received key information. Checks whether the key information on the requested channel is correct using the channel ID and matches the version information of the current key table, extracts the key information, stores it in the storage 304, checks the key application time of the key table, and applies it to decryption. And a key to be set. The method of claim 11, In the decryption processing step, a method of selecting a key to be used for decryption among the keys in the key table and synchronizing the keys according to the time when the key is to be applied (1) calculating a value of 'reference time + key application time' in the index order in the current key table until the value is greater than the current time; (2) if the value of the reference time + key application time is greater than the current time, setting the key of the corresponding index as a key to be used when decrypting the current key; (3) setting the key corresponding to the next index as the decryption key if the value of 'reference time + key application time' becomes equal to the current time; And (4) performing decoding and repeating from step (1) each time a TS packet is input.

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