KR100655027B1 - Digital two-way communication control device and its method - Google Patents

Abstract

The interface block 11 formats the input downstream data STRM. The CPU 12 receives the format-converted data DIF to implement the MAC function. The TEK processing block 13 receives the TEK processing data DTEK obtained from the data DIF, analyzes the data structure, and performs decoding processing based on the analysis result.

Description

DIGITAL TWO-WAY COMMUNICATION CONTROL DEVICE AND ITS METHOD}

The present invention relates to an apparatus for performing two-way control in digital two-way communication, and particularly belongs to a technique for performing configuration optimization related to downlink communication from the central apparatus side to the terminal apparatus.

The digital bidirectional communication system represented by bidirectional CATV is composed of a bidirectional communication network in which a plurality of terminal devices are connected to a central device. In this individual terminal apparatus, the bidirectional control of the downlink communication from the central apparatus side to the terminal apparatus and the uplink communication from the terminal apparatus side to the central apparatus is called a MAC (Media Access Control) function, and usually, a sublayer (sub) The processing function is realized by decrypting a protocol having a structure specific to MAC embedded as a layer).

As an example of the MAC structure, the MCC (Multimedia Cable Network Systems Partners), a group of US cable operators and cable TV sets suppliers, is currently the industry standard Data Over Cable Service Interface Specifications (DOCSIS) method This exists. The details are disclosed in "Radio Frequency Interface Specification SP-RFIv1.1-I06-001215" in the "Data-Over-Cable Service Interface Specifications" specification provided by CableLabs (Cable Television Laboratories Inc.) in the United States.

Usually, in downlink communication, video data is mainly transmitted. Therefore, the communication data has an MPEG structure, but the MAC structure is defined as its sublayer. Since the downlink communication is allocated a communication channel frequency in a relatively wide band, the communication control itself is relatively simple, but since the video data is transmitted, it is necessary to handle an enormous amount of data. do.

In the upcoming communication, on the other hand, control data is usually transmitted. This control data includes the command request from the terminal apparatus side and status display data for notifying the status of each terminal apparatus. Receiving the control data transmitted in the uplink communication, the central apparatus responds to the request command of each terminal device or transmits various kinds of information for correctly controlling the terminal device as the control data for the downlink communication. In the uplink communication, since a plurality of communication channel frequencies are allocated to a narrow band, complex control is generally required, such as a collision between a plurality of terminal devices or a case in which a required communication channel frequency is not obtained. It greatly affects the communication performance in two-way communication.

The DOCSIS MAC structure basically has the same structure as the Ethernet communication in order to increase the affinity with IP communication according to Ethernet, but sets various header fields as DOCSIS-specific areas. Among them, a cipher or other additional function is defined by a field of a variable length area called an "extended header".

To realize the MAC function, as shown in the specification, it is necessary to analyze various data structures having a complicated multilayer structure, and then execute various processes at appropriate timings. Realizing a large number of processing for a huge number of combinations, and verifying the accuracy of the combination operation, is very difficult and has a high throughput.

Next, focusing on the respective processing contents, the individual processings that make up the MAC function are mainly the calculation processing of the control system, and basically the individual processing such as data filtering (allocation), synchronization processing, arrangement change, formatting, and the like. It is a combination. These individual processes themselves are never called heavy loads.

However, the MAC function includes data security that is indispensable to the communication system, and the details of the DOCSIS method are detailed in the Baseline Privacy Plus Interface in the Data-Over-Cable Service Interface Specifications, published by CableLabs of the United States. Specifications SP-BPI + -106-001215.

The security function of the MAC function is called Baseline Privacy and uses a protocol called BPKM (Baseline Privacy Key Management). Since BPKM performs secure key exchange, it has a function of encrypting and receiving the encryption key itself, and a message authentication function for confirming that the message of the encryption key exchange has been sent from the correct partner or that there is no write change. . In BPKM, a key distribution is performed using an Authorization Key, which is to be a master key, and a two-step key called a DES encryption key (TEK), which is actually used to encrypt and decrypt data.

The terminal device receives the Authorization Key encrypted by the RSA public key method and decrypts the Authorization Key using the RSA public key. Next, TEK data is obtained from the obtained Authorization Key through several processes of decrypting and authenticating the TEK. Finally, the TEK data is used to decrypt the actual communication data. In this case, the decoding processing of the RSA encryption for decoding the Authorization Key and the decoding of the DES encryption for decoding the TEK data also require individual processing since the numerical operations using a plurality of 64-bit units are required in parallel and repetition. It can also be said that the processing is quite heavy.

In order to realize the MAC function for performing bidirectional control in digital bidirectional communication, it is necessary to combine these processes.

Challenge

 The MAC function is generally realized by using a general purpose processor (CPU). This is because the CPU has the advantage of being able to flexibly cope with complex processing, and the verification and the number of functions for establishing the reliability of the system can be relatively easily realized.

However, in order to realize the enormous processing of the MAC function, it is essential to use a high performance CPU. Not only does it occupy the CPU, it is very difficult to achieve all the desired functions on a single CPU. Therefore, in order to construct a device that realizes all the MAC functions, the circuit scale becomes extremely large, resulting in an unrealistically high cost device.

In view of the above problems, the present invention aims at reducing the load on CPU processing in digital bidirectional communication control and realizing the appropriateness of the overall circuit size of the apparatus.

The present invention provides an apparatus for performing bidirectional control in digital bidirectional communication, comprising: an interface block for converting input downstream data to generate downlink data, and data other than TEK (Traffic Encryption Key) processing data among the downlink data; And a TEK processing block which receives the TEK processing data obtained from the downlink data, analyzes the data structure, and executes decoding processing based on the analysis result. And a TEK processing block which inputs TEK processing data, analyzes the MPEG structure of the TEK processing data and the MAC structure embedded in the MPEG structure, and indicates the state and meaning of MAC data which is data having a MAC structure. And a structural analysis block for outputting status information data.

As a result, during the process for realizing the MAC function, the structural analysis of the TEK processing data and the decoding processing based on the analysis result are executed by a TEK processing block separate from the CPU. Therefore, the load of CPU processing is reduced and the whole apparatus can be comprised by the appropriate circuit scale.

The TEK processing block in the digital two-way communication control apparatus according to the present invention determines the encrypted portion of the TEK processing data with reference to the MAC state information data, and the TEK data for decrypting the encrypted portion. It is preferable to have a decryption block which decodes using and integrates the decryption result with an unencrypted portion.

The structure analysis block in the digital bidirectional communication control apparatus according to the present invention analyzes the MPEG header which is the header of the MPEG structure among the TEK processing data, and displays the MAC data position signal indicating the position of the MAC data, and the MAC frame. An MPEG header analysis block for outputting a MAC data head position signal indicating a head byte position, the MAC data position signal and a MAC data head position signal as inputs, and an extension header and MACMM (MAC Management) in the MAC header which is a header of the MAC structure. Recognizes the status information for fields other than the header, and outputs the extension header position information data indicating the position of the extension header when the extension header is present in the TEK processing data, and the MACMM header is present in the TEK processing data. A MAC header analysis block for outputting MACMM header location information data indicating a location of a MACMM header, and the extended header location information data. In addition, an extension header analysis block which checks each field of the extension header and outputs extension header state information data indicating the state information of the extension header, receives the MACMM header position information data, checks each field of the MACMM header, and checks the MACMM header. And a MACMM header analysis block for outputting MACMM header status information data indicating status information of the header, wherein the MAC header analysis block receives the extended header status information data and the MACMM header status information data, and includes an extended header and a MACMM in the MAC header. Generating the MAC state information data based on the state information of each field other than the header, the state information of the extended header indicated by the extended header state information data, and the state information of the MACMM header indicated by the MACMM header state information data. It is desirable to.

The MPEG header parsing block preferably checks the field of the MPEG header to detect the position of the MAC data and the head byte position of the MAC frame, and outputs the MAC data position signal and the MAC data head position signal.

Alternatively, the MAC header analysis block preferably performs error detection of the MAC header by HCS checking. Alternatively, the MAC header analysis block performs a check on a field indicating the length of the MAC data in the MAC header. The check is performed by calculating the data length of the MAC frame with reference to the MAC data head position signal. It is preferable to carry out by determining whether the length coincides with the sum of the value of the field and the predetermined data length. Alternatively, the MAC header analysis block performs error detection of the MAC header by HCS check, MAC frame length check and extended header length check, and performs MAC frame length check and extended header length check. It is preferable to invalidate the check result by the HCS check when the check result is no error.

Alternatively, the extended header analysis block may check the field of the extension header, determine the data length or type of the extension header, and if the field value of the extension header is invalid with reference to the extension header position information data. It is preferable to recognize that there is an error and output the contents as the extended header state information data.

Alternatively, the MACMM header analysis block may check the field of the MACMM header, determine the data length and type of the MACMM, and if the field data value of the MACMM header is invalid, by referring to the MACMM header position information data. It is preferable to recognize that there is an error and to output the contents as the MACMM header status information data.

In the digital bidirectional communication control apparatus according to the present invention, the decryption block selects encrypted and unencrypted portions of the TEK processing data from the TEK processing data with reference to the MAC state information data. Extract TEK control data for selecting TEK data, refer to the extracted TEK control data, select TEK data to be used for decryption among a plurality of pre-stored TEK data, and convert the encrypted portion to the bit width of the decoding processing unit. It is desirable to decode using the selected TEK data, and to integrate the undecrypted data with the decoded data.

In addition, the present invention provides a method for performing bidirectional control in digital bidirectional communication, comprising: converting input downstream data to generate downlink data, and processing a TEK (Traffic Encryption Key) of the downlink data by a CPU; Receiving data other than the data to realize the MAC (Media Access Control) function, receiving the TEK processing data obtained from the downlink data by the TEK processing block, and analyzing the data structure based on the analysis result. And a TEK processing step for executing the decoding process, wherein the TEK processing step analyzes the MPEG structure and the MAC structure embedded in the MPEG structure in the TEK processing data, and indicates the state and meaning of the MAC data which is the data having the MAC structure. And a structural analysis step of generating state information data.

The TEK processing step in the digital two-way communication control method according to the present invention is characterized in that the encrypted portion of the TEK processing data is determined with reference to the MAC state information data, and the encrypted portion is TEK data for decrypting. It is preferable to have a decryption step of decrypting using a function and integrating the decryption result with an unencrypted part.

In the structural analysis step, the MPEG header, which is the MPEG structure header of the TEK processing data, is analyzed to generate a MAC data position signal indicating the position of the MAC data and an MPEG data position position signal indicating the head byte position of the MAC frame. By using the header analysis step and the MAC data position signal and the MAC data head position signal, status information is recognized for fields other than the extended header and MACMM (MAC Management Message) header in the MAC header which are MAC structure headers. MAC header which generates the extended header position information data indicating the position of the extension header when the header exists in the TEK processing data, and generates the MACMM header position information data indicating the position of the MACMM header when the MACMM header is present in the TEK processing data. Receiving the extension header position information data, checking each field of the extension header, and obtaining the state information of the extension header. An extended header analysis step of generating extended header state information data, a MACMM header receiving the MACMM header position information data, checking each field of the MACMM header, and generating MACMM header state information data indicating the status information of the MACMM header. And an analysis step, wherein each field state information other than the extended header and the MACMM header in the MAC header determined in the MAC header analysis step, the extended header state information indicated by the extended header state information data, and the MACMM header state information. It is preferable to generate the MAC state information data based on the state information of the MACMM header indicated by the data.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram showing the structure of a digital bidirectional communication control device according to an embodiment of the present invention.

FIG. 2 is a diagram showing the internal structure of the structural analysis block shown in FIG. 1; FIG.

3 is a state machine of MPEG header analysis according to the embodiment of the present invention;

4 illustrates the format of an MPEG header.

5 is a diagram illustrating a format of MPEG data including a pointer field.

6 is a state machine of MAC header analysis according to the embodiment of the present invention;

7 illustrates the format of a MAC header.

8 is a view for explaining a MAC header error detection method other than the HCS check.

9 is a state machine of the extended header analysis according to the embodiment of the present invention.

10 illustrates the format of an extension header.

FIG. 11 is a diagram illustrating a format of an extended header privacy example.

12 is a state machine of the MACMM header analysis according to the embodiment of the present invention.

13 illustrates the format of a MACMM header.

14 is a flowchart showing the operation of a decoding block according to the embodiment of the present invention.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described, referring drawings.

1 is a block diagram showing the configuration of a digital bidirectional communication control device according to an embodiment of the present invention. The digital bidirectional communication control device 1 shown in FIG. 1 executes bidirectional communication control in a bidirectional communication network composed of a central device and a plurality of terminal devices, and is configured inside the terminal device.

In Fig. 1, reference numeral 11 denotes an input of downstream data (STRM), which is an image transmitted from the central unit, and transmission control data, and is converted to format to be sent to the CPU 12, thereby generating CPU interface data DIF as downstream data. Interface block 12 for receiving CPU interface data (DIF) through the CPU bus 15 to realize a MAC (Media Access Control) function, and 14 for data with the CPU 12 via the CPU bus 15. It is a data storage device that performs sorghum.

13 is inputted TEK processing data (DTEK), which is data used for TEK processing among images and transmission control data, to analyze the data structure, confirm existence of encryption, decrypt data, and convert data. Is a TEK processing block for outputting TEK processing result data (RTEK). The TEK processing block 13 executes structural analysis of the TEK processing data DTEK, and outputs the delay TEK processing data DTTK and the MAC status information data STMC, and the delay TEK processing. Decoding for outputting the TEK processing result data (RTEK) by performing encryption / determination of the delay TEK processing data (DDTK), decoding processing, and bit conversion of the data using the data (DDTK) and the MAC state information data (STMC). Block 30. The TEK processing result data RTEK output from the TEK processing block 13 is input to the data storage device 14.

Here, the MAC state information data STMC indicates the state and meaning of the data (MAC data) having the MAC structure, which is a sublayer for communication network processing, embedded in the MPEG structure in the TEK processing data DTEK. The delay TEK processing data DTTK is a delay of 0 or 1 clock or more of the TEK processing data DTEK in order to correspond in time to the MAC state information data STMC. The CPU interface data DIF includes a control signal of the CPU bus 15 in addition to the result data of the format conversion of the downstream data STRM.

The operation of the digital bidirectional communication control device 1 shown in FIG. 1 will be described.                 

When the terminal apparatus receives the downstream data STRM, it sends it to the interface block 11 in the digital bidirectional communication control apparatus 1. The interface block 11 converts the format of the downstream data STRM and outputs it as CPU interface data DIF. The CPU 12 receives the CPU interface data DIF through the CPU bus 15, and executes various processes for realizing the MAC function together with the data storage device 14. However, TEK processing data DTEK, which is data used for TEK processing among the MAC functions, is sent from the CPU 12 to the TEK processing block 13 via the CPU bus 15.

In the TEK processing block 13, when the TEK processing data DTEK is input, the structural analysis block 20 first performs a structural analysis of the MPEG structure of the TEK processing data DTEK and the MAC structure embedded in the MPEG structure. do. The delay TEK processing data DTTK and the MAC status information data STMC output from the structure analysis block 20 are sent to the decoding block 30. The decryption block 30 executes a decryption process on the data encrypted according to the DES (Data Encryption Standard) on the central device side to protect the data confidentiality of the delay TEK process data (DDTK), and transmits the data to the data storage device 14. Outputs TEK processing result data (RTEK). Details of the processing in the structural analysis block 20 and the decoding block 30 will be described later.

With this arrangement, the structural analysis of the TEK processing data DTEK during the processing for realizing the MAC function and the decoding processing based on the analysis result are carried out in a TEK processing block 13 separate from the CPU 12. Is executed by This greatly reduces the CPU processing load. In addition, since most of the processing in the TEK processing block 13 is realized by repeatedly performing similar numerical operations in parallel, the hardware configuration is also simple. Therefore, the whole apparatus can be comprised by an appropriate circuit scale.

Here, by making the path for sending the TEK processing data DTEK from the CPU bus 15 to the TEK processing block 13 bidirectionally, a part of the TEK processing can be executed by the CPU 12. In addition, by directly transmitting video and control data from the interface block 11 to the TEK processing block 13, the CPU bus 15 can be reduced in occupancy and the CPU processing can be speeded up. In addition, bidirectional communication control is possible by bidirectionally providing the input path of the downstream data STRM and the path of the CPU interface data DIF from the interface block 11 to the CPU bus 15, respectively.

<Structure Analysis Block>

FIG. 2 is a block diagram showing the internal structure of the structural analysis block 20 shown in FIG. In Fig. 2, reference numeral 21 denotes an MPEG header, which is a header of an MPEG structure among TEK processing data DTEK, extracts a MAC structure from the MPEG structure, and indicates a MAC data position signal (PMC) and a MAC frame indicating a data position of the MAC data. An MPEG header analysis block that outputs a MAC data head position signal (LPMC) indicating the head byte position of a. The MPEG header analysis block 21 outputs the MAC data position signal PMC and the MAC data head position signal LPMC relating thereto together with the delay TEK processing data DTTK obtained by delaying the TEK processing data DTEK. .

22, the MAC data position signal PMC and the MAC data head position signal LPMC are input, except for the extension header and the MACMM (MAC Management Message) header in the header portion (MAC header) of the MAC data having the MAC structure. The MAC header analysis block performs an analysis on a portion of and determines the state information of each field, that is, the meaning of data. The MAC header analysis block 22 also outputs the extended header position information data PEH indicating the position of the extended header when the extended header exists in the delay TEK processing data DDTK, and the delay TEK processing data DDTK. When the MACMM header is present, MACMM header location information data (PMM) indicating the location of the MACMM header is output.

Further, 23 receives the extended header position information data (PEH), performs extended header analysis in the MAC header, and outputs extended header status information data (STEH) indicating the state of the extended header, that is, the state and meaning. Block 24 is a MACMM header analysis block that receives MACMM header position information data (PMM) and performs MACMM header analysis, and outputs MACMM header status information data (STMM) indicating status information, that is, status and meaning of the MACMM header. to be.

The MAC header analysis block 22 receives the extended header status information data STEH and the MACMM header status information data STMM, and the status information of fields other than the extended header and MACMM header in the MAC header, and the extended header status information. Based on the state information of the extended header indicated by the data STEH and the state information of the MACMM header indicated by the MACMM header state information data STMM, the MAC state information data STMC is generated.

The operation of each analysis block 21 to 24 will be described in more detail.

<MPEG Header Analysis>

The MPEG header analysis block 21 extracts the MAC structure from the MPEG structure by analyzing the MPEG header in the TEK processing data DTEK. Specifically, each field of the MPEG header is checked in order, the data meaning of each field is determined, and a state is given to the data.                 

3 is a diagram illustrating a state machine of MPEG header analysis in the MPEG header analysis block 21. 4 is a diagram illustrating the format of an MPEG header. The processing flow of MPEG header analysis will be described with reference to FIG.

The state of the state machine transitions by byte clock. The initial state of the state is "IDLE". If there is an error in the TEK processing data DTEK, the state is set to "ERR".

When the state is " IDLE ", the state is maintained until the packet synchronization included in the TEK processing data DTEK indicates the head of the MPEG frame (S11). When the packet synchronization indicates the head of the MPEG frame, when the head data of the MPEG data, that is, the value of the MPEG packet sync byte data (sync byte) shown in FIG. 4 is "0x47", the state is changed to "S1". (S12). On the other hand, when it is not same as the above, the state is set to "ERR".

When the state is "S1", the value of the TEI (Transport Error Indicator) data shown in FIG. 4 is "0x0" (S13), and the upper 5 bit values of the PID (Program ID) shown in FIG. 4 are "0." When " 1F " (S14), the state is set to " S2 ", otherwise the state is set to &quot; ERR &quot;. The TEI data indicates whether or not there is an error in the MPEG structure and is added in the error correction process. In addition, PID is set in MPEG data which transmits MAC frame of DOCSIS specification.

When the state is " S2 ", the state is " S3 " when the lower 8 bit value of the PID is " 0xFE ", otherwise, the state is " ERR " (S15). When the state is "S3", the value of the transport scrambling control data shown in FIG. 4 is "0x0", and the value of the adaptation field control data shown in FIG. At 0x1 ", the state is set to" S4 ", otherwise, the state is set to" ERR "(S16). The transmission scramble control data is control data relating to scramble control, and the adaptation field control data is field allocation control data for DOCSIS.

When the state is "S4", when the value of the payload unit start indicator (PUSI) shown in FIG. 4 is "0x1", it is determined that the pointer field exists and the state is set to "POINTER" (S17). Otherwise, the status is set to "MAC_FRM". PUSI indicates whether the head of MAC data exists in MPEG data. The pointer field is important data when generating the MAC data head position signal LPMC, which will be described later in detail.

When the state is "MAC_FRM", the state is maintained until the MPEG packet sync byte data appears (S18), and when the MPEG packet sync byte data appears and the value is "0 x 47" (S12), the state is changed to "S1". "" Otherwise, the status is set to "ERR".

On the other hand, when the state is "ERR", the state is maintained until packet synchronization indicates the head of MPEG data (S19), and when the packet synchronization indicates the head of MPEG data, the value of MPEG packet synchronization byte data is "0." In the case of x47 ", the state is set to" S1 "(S12), otherwise, the state is maintained.

5, a method for generating a pointer field, a MAC data head position signal LPMC and a MAC data position signal PMC will be described. FIG. 5 is a diagram conceptually showing a format of MPEG data including a pointer field, and MPEG data as shown in FIG. 5 is included in TEK processing data DTEK.                 

In FIG. 5, the PUSI value of the MPEG header is "0x1", indicating that there is a pointer field. There is a pointer field after the MPEG header, and the value of the pointer field is M (M: integer). This indicates that after the pointer field, the remaining data of one MAC frame (MAC Frame # 1) is present in M bytes, and a new MAC frame (MAC Frame # 2) starts thereafter. Therefore, the position of the head byte of the MAC frame can be detected from the value M of the pointer field.

That is, since the data whose state is "POINTER" is a pointer field, a pointer field counter is constructed, and the pointer field counter performs calculations from the position of the "POINTER" state, that is, the position of the pointer field. When the value calculated by the pointer field counter is equal to the value of the pointer field, it is recognized that the position is the first byte position of the MAC frame. This generates the MAC data head position signal LPMC.

In addition, since the data for the state "MAC_FRM" is a MAC structure, it generates a MAC data position signal (PMC) accordingly. 5 conceptually shows the relationship between MPEG data, MAC data head position signal LPMC and MAC data position signal PMC.

In addition, the state information of each field obtained here is kept in a register. In order to associate the TEK processing data with the status information, the TEK processing data DTEK is delayed by 0 or 1 clock or more to generate the delay TEK processing data DDTK.

Here, the MPEG frame length counter that calculates the MPEG structure data length (188 bytes) as well as the front protection and back protection counters for the TEI data for the protection function of the MPEG structure is configured so that the TEI data may be corrupted. Even if not shown, if the length of the MPEG structure data up to the head of the next MPEG structure is not 188, it is possible to set a function that determines that the MPEG structure is an error.

<MAC header interpretation>

The MAC header analysis block 22 executes MAC header analysis in the delay TEK processing data (DDTK). Specifically, each field of the MAC header is checked in order, the data meaning of each field is determined, and a state is given to the data.

6 is a diagram showing a state machine of MAC header analysis in the MAC header analysis block 22. As shown in FIG. The state machine of MAC header analysis operates only when the MAC data position signal PMC is valid. 7 is a diagram showing the format of MAC data. 6, the processing flow in MAC header analysis will be described.

The state of the state machine transitions by byte clock. The initial state of the state is "IDLE". If there is an error in the MAC structure, the state is set to "ERR".

When the state is "IDLE", the state is maintained when the MAC data head position signal LPMC is not valid, and the state is "FC" when it is valid (S21). Here, the MAC header when the state is " FC " is FC (Field Control) data, which indicates the type of MAC data and the presence or absence of an extension header that enables expansion of the MAC data configuration.

When the state is "FC", the value of FC data is analyzed (S22). If the FC data value indicates SYNC data, the state is set to "PARM_T" (S22A). If the MAC data value is shown, the state is set to "PARM_M" (S22B). (S22C). If the FC data value is 0xff and STUFF bytes, which are dummy data of MPEG structure data, are present (S22D), the state is set to "ERR" if the FC data is other (S22E). . Here, the SYNC data is a MAC structure for transmitting data required for synchronization processing transmitted from the central apparatus side, and the MACMM transmits band allocation data used for MAC control, data required for synchronization processing, and the like transmitted from the central apparatus side. A MAC structure for transmitting the PacketPDU is a MAC structure for transmitting normal video data.

The presence or absence of an extension header in the MAC data is determined by the value of EHDR_ON included in the FC data. If it is "0", there is no extension header. If it is "1", there is an extension header.

When the states are "PARM_T", "PARM_M", and "PARM_D", the state is set to "LEN_H". When the state is "LEN_H", the state is set to "LEN_L". When the state is "LEN_L", the presence or absence of the extension header is determined by the value of EHDR_ON (S23). If there is an extension header, the state is set to "EHDR", otherwise the state is set to "HCS_H".

Since the period in which the status is "EHDR" is the location of the extended header, the extended header location information data PEH is generated and transmitted to the extended header analysis block 23 together with the delay TEK processing data DTTK. The processing contents of the extended header analysis block 23 will be described later.

When the state is "EHDR", the state is maintained while the processing of the extended header analyzing block 23 is executed. When it is confirmed from the extended header state information data STEH outputted from the extended header analyzing block 23 that the extended header analyzing process is normally completed, the state is set to "HCS_H" (S25). On the other hand, when it is confirmed from the extended header state information data (STEH) that an error exists in the extended header, that is, an error exists in the MAC structure, the state is set to "ERR" (S24). The extended header state information data STEH is information representing the state of each field of the extended header.

When the state is "HCS_H", the state is set to "HCS_L". When the state is "HCS_L", the state is set to "DA_LD". When the state is "DA_LD", the state is set to "SA_LD".

When the status is " SA_LD ", it is checked whether or not the destination address (DA) of the delay TEK processing data (DDTK) and the address of the terminal device match. If not, the data to be processed by the terminal device. Since it is not, the state is set to "ERR" (S26). When there is a match, it is determined whether the MAC structure is SYNC data or MACMM, that is, whether there is a MACMM header in the MAC structure, and if so, the state is set to "MAC_MNG", otherwise the state is set to "TL_H" ( S27).

Since the period in which the status is "MAC_MNG" is the location of the MACMM header, the MACMM header location information data (PMM) is generated and transmitted to the MACMM header analysis block 24 together with the delay TEK processing data (DDTK). The MACMM header analysis process will be described later.

When the state is "MAC_MNG", the state is maintained while the processing of the MACMM header analysis block 24 is executed. When it is confirmed from the MACMM header state information data (STMM) output from the MACMM header analysis block 24 that the MACMM header analysis process is normally completed, the state is set to "VALID" (S29). On the other hand, when it is confirmed from the MACMM header state information data (STMM) that an error exists in the MACMM header, that is, an error exists in the MAC structure, the state is set to "ERR" (S28). MACMM header status information data (STMM) is information indicating the state of each field of the MACMM header.

When the status is " TL_H ", it is checked whether or not the source address (SA) of the delay TEK processing data (DDTK) matches the address of the terminal apparatus. It is determined that the state is "ERR", and when it does not match, the state is "TL_L" (S2A). When the status is "TL_L", the status is set to "VALID".

When the state is "VALID", the state is maintained until the last data of the MAC structure, and when the last data of the MAC structure is received, the state is "FC", and the structure analysis of the next MAC structure is executed (S2B). .

That is, as a result of the operation according to the state, the MAC header analysis block 22 generates the extended header position information data (PEH) because the period in which the state is "EHDR" indicates the extension header, and the period in which the state is "MAC_MNG" Since the MACMM header is shown, MACMM header location information data (PMM) is generated. The MAC state information data STMC is generated from the extended header state information data STEH and the MACMM header state information data STMM and the MAC header state information analyzed by the MAC header analysis block 22. In order to correspond with the state obtained here, the delay TEK processing data DDTK is further delayed and output from the structural analysis block 20.

(Error detecting MAC header)

Here, according to the HCS check, error detection of the MAC header is executed. The HCS check is a method of detecting MAC header errors by CRC calculation of MAC headers other than HCS (FC field, PARM field, LEN field, EHDR field) in the structure of MAC data shown in FIG. to be.

8 is a diagram for explaining error detection of MAC headers other than the HCS check. In Fig. 8, (a) shows the LEN field check (MAC frame length check), and (b) shows the PARM field check (extended header length check).

As shown in Fig. 8A, a LEN counter for calculating the LEN field is used for checking the LEN field value. The LEN counter starts calculation when the MAC data head position signal LPMC becomes valid at a position indicating the head of one MAC data (MAC data 1), and starts the calculation at a position indicating the head of the next MAC data (MAC data 2). When it is valid, the calculation stops. Thus, the value of the LEN counter indicates the data length of MAC data 1, and if there is no error, it will match the MAC_LEN length (= LEN field value + 6 bytes (corresponding to FC, PALM, LEN, HCS field length). Here, when the value of the LEN counter matches the length of MAC_LEN, it is determined that there is no error in the LEN field, and when the value of the LEN counter does not match the length of MAC_LEN, it is determined that there is an error in the LEN field.

As shown in Fig. 8B, a PARM counter that calculates only the PARM field value is used to check the PARM field. The PARM counter calculates at the position where 6 bytes (corresponding to the FC, PLM, and LEN field lengths) have progressed since the MAC data head position signal LPMC became valid at the position indicating the head of one MAC data (MAC data 3). Start and stop calculation at the position calculated by the PARM field value. As a result, the position where the PARM counter stops calculating becomes equivalent to the end of the extension header, and then the state analysis according to FIG. 6 is advanced. If the final position of the extended header indicated by the PARM counter is incorrect, the result of the subsequent status analysis will be an error. Therefore, when the status analysis of the MAC data 3 ends, it is determined that there is no error in the PARM field when the status result is not "ERR", and the result of the PARM field check is ignored when the status result is "ERR".

In the FC field check, it is confirmed that the processing of checking the value of the FC field and the subsequent state analysis processing according to Fig. 6 are adapted to the type of data determined as the value of the FC field, and the status result is " ERR " If not, it is determined that there is no error in the FC field. If the status result is "ERR", the FC field check result is ignored.

In the check of the EHDR field, it is determined that there is no error in the EHDR field when the state analysis result of the extended header analysis block 23 described later is not "ERR", and an error in the EHDR field when the state analysis result is "ERR". Judging that there is.

As a result of checking each field of the MAC header as described above, if there is no error for all the fields, it is possible to set a function for determining that there is no error in the MAC header even if the HCS check result is an error. For example, when the check result of the MAC frame length check and the extended header length check is error free, the check result of the HCS check may be invalidated. It is also possible to perform MAC header error detection only by checking the HCS, without using such a MAC header error detection method.

<Expand Header Analysis>

The extension header analysis block 23 analyzes this extension header when an extension header exists in the delay TEK processing data DDTK. Specifically, each field of the extension header is checked in order, the data meaning of each field is determined, and a state is given to the data.                 

9 is a diagram illustrating a state machine of extended header analysis in the extended header analysis block 23. 10 is a diagram illustrating the format of an extended header. As shown in Fig. 10, the extension header is composed of an EH TYPE field indicating the type of the extension header, an EH VALUE field indicating the data portion of the extension header, and an EH LEN field indicating the length of the EH VALUE field. Each field of EH LEN and EH VALUE is repeated in a set.

9, the processing flow in extended header analysis will be described. The state of the state machine transitions by byte clock.

If the state is "IDLE" which is the initial state, the state is set to "EH_TL" when the extended header positional information data PEH transmitted from the MAC header analysis block 22 is valid, and otherwise maintained. (S31).

The MAC data when the state is "EH_TL" indicates the type of extension header and the data length. There are three kinds of extension headers: That is, when downlink privacy, which is data related to encryption of MCA data, and MAC data are transmitted continuously and they have the same header, a payload header suppression (PHS) function, which is a function that enables bandwidth saving by compressing repeated headers, is performed. Data "Downstream PHS", and "Null" used to embed the extension header. 11 is a diagram illustrating a format of an extended header of "Downstream Privacy".

When the status is "EH_TL", the status is set to "EH_VAL" when the MAC data indicates any one of the above three types. Otherwise, it is determined that there is an error in the delay TEK processing data (DDTK) and the status is set to "ERR". (S32).                 

When the status is "EH_VAL" and the extension header is "Downstream Privacy" (S33), the value of the Version Data (Protocol Version Number) indicating the version of the protocol is not 0x01 or the end of the EH VALUE field. If the value of the reserved data, which is data, is not 0x00, it is determined that there is an error in the delay TEK processing data DDTK, and the state is set to "ERR" (S34, S35).

If not, it is checked whether the EH VALUE field is the last (S36). The confirmation here is performed by the EH LEN counter which calculates the value of the EH LEN field. That is, when the value of the EH LEN counter does not match the value of the EH LEN field, the state is maintained. On the other hand, if there is a match, it is checked whether the extended header field is the last (S37). The check here is performed with reference to the extended header position information data (PEH). At the end of the extension header field, it is determined that the analysis of the extension header has ended normally, and the state is set to "IDLE". Otherwise, the state is set to "EH_TL".

As a result, the extended header analysis block 23 indicates that the error information of the extended header and the error status information when it is determined that there is an error in the state information of each field of the extended header, the delay TEK processing data (DDTK), and the extension header have been completed normally. The normal termination status information when judged is output to the MAC header analysis block 22 as the extended header status information data STEH.

<MACMM header interpretation>

The MACMM header analysis block 24, when there is a MACMM header in the delay TEK processing data (DDTK), analyzes the MACMM header. Specifically, each field of the MACMM header is checked in order, the data meaning of each field is determined, and a state is given to the data.

12 is a diagram showing a state machine of MACMM header analysis in the MACMM header analysis block 24. As shown in FIG. 13 shows the format of the MACMM header. In Fig. 13, DA is a source address field of delay TEK processing data (DDTK), SA is a source address field of delay TEK processing data (DDTK), MsgLEN is a data length field of MACMM, and DSAP is based on ISO 8802-2. A field indicating an LLC source address point, an SSAP field indicating an LLC source address point according to ISO 8802-2, a Control field indicating an Unnumbered information frame field according to ISO 8802-3, a Version field indicating a version of MACMM, Type is a field indicating the type of MACMM, RSVD is a preliminary data field for placing the MAC Management Payload on a 32-bit boundary, MAC Management Payload is a real data field of the MACMM, and CRC is a CRC calculation for DA to MAC Management Payload. Check sequence data field.

12, the processing flow in MACMM header analysis will be described. The state of the state machine transitions by byte clock.

If the state is " IDLE " which is the initial state, the state is set to " MSGL_H " when the MACMM header positional information data (PMM) transmitted from the MAC header analysis block 22 is valid; S41).

When the status is "MSGL_H", the source address SA of the received delay TEK processing data DDTK is compared with the address of the terminal apparatus, and when it matches, the delay TEK processing data DTTK is judged to be invalid data. Is set to "ERR", and if not, the status is set to "MSGL_L" (S42).

When the state is "MSGL_L", the state is set to "DSAP". When the status is "DSAP", when the value of the delay TEK processing data (DDTK) is 0x00, the status is "SSAP". Otherwise, it is determined that the delay TEK processing data (DDTK) is invalid, and the status is set to "ERR." "(S43).

When the status is "SSAP", when the value of the delay TEK processing data (DDTK) is 0x00, the status is set to "CONTROL". Otherwise, it is determined that the delay TEK processing data (DDTK) is invalid data. It is set to "ERR" (S44).

When the status is "CONTROL", the status is set to "VERSION" when the value of the delayed TEK processing data (DDTK) is 0x03. Otherwise, it is determined that the delayed TEK processing data (DDTK) is invalid data. It is set to "ERR" (S45).

When the status is "VERSION", when the value of the delay TEK processing data (DDTK) is 0x01 or 0x02, the status is "TYPE". Otherwise, the delay TEK processing data (DDTK) is invalid data. The judgment is made as "ERR" (S46).

When the state is "TYPE", the state is set to "RSVD". When the state is " RSVD ", it is determined that the MACMM header analysis is normally completed, and the state is " IDLE ".

As a result, the MACMM header analysis block 24 determines that the status information of each field of the MACMM header, the error status information when it is determined that there is an error in the delay TEK processing data (DDTK), and the MACMM header analysis have been completed normally. If so, the normal termination status information is output to the MAC header analysis block 22 as MACMM header status information data (STMM).                 

By the processing of the MAC header analyzing block 22, the extended header analyzing block 23, and the MACMM header analyzing block 24, the processing of the structural analysis block 20 is completed. After the end of the processing, the MAC state information data STMC and the corresponding delay TEK processing data DTTK are sent to the decoding block 30.

<Decryption block>

The decoding block 30 receives the delay TEK processing data DTTK and the MAC state information data STMC outputted from the structural analysis block 20, and protects the confidentiality of the data in the delay TEK processing data DDTK. In order to do this, the decryption process is performed on the data encrypted by the DES (Data Encryption Standard) on the central device side, and the processing result is output to the data storage device 14 as TEK processing result data (RTEK).

14 is a flowchart showing the operation of the decoding block 30. In Fig. 14, 31 denotes input of delay TEK processing data DTTK and MAC state information data STMC, and the presence or absence of encryption of the delay TEK processing data DDTK is determined, and the first decoding processing target data DD1 and An encryption presence check block that outputs out-of-decoding data DDX, 32 converts the first decoding-processing data DD1 into 64-bits, which is a bit width adapted to the decoding process, and outputs it as second decoding-processing data DD2. Is a first bit conversion block. 33 is a TEK collation data extraction block for extracting TEK collation data (ITEK) for selecting TEK data (TEK) from the delay TEK processing data (DDTK), and 34 is a TEK collation data (TEK) using TEK collation data (ITEK). ) Is a TEK data extraction block. 35 is a decoding processing block which performs decoding processing on the second decoding processing target data DD2 and outputs the first decoding processing result data RD1, and 36 denotes that the first decoding processing result data RD1 is outside the decoding processing target. The second bit conversion block 37, which is converted into 8 bits having the same bit width as the data DDX and output as the second decoding result data RD2, 37 is the second decoding result data RD2 and the non-decoding data DDX. ), A data combining block 38 for outputting as combined data (CBD), 38 converts the combined data (CBD) into a bit width adapted to the data storage device 14, and outputs it as TEK processing result data (RTEK). The third bit conversion block.

Here, the first decryption processing data DD1 is data of the DES encrypted portion of the delay TEK processing data DDTK, and the non-decoding data DDX is undecrypted DES encryption of the delay TEK processing data DDTK. Part of the data. TEK data (TEK) is data for decryption, and in this case, it is actually a DES encryption key used for encrypting and decrypting data. The TEK collation data ITEK is sequence data for inquiring to select TEK data TEK to be used for decoding from a plurality of TEK data previously held. Here, the TEK data TEK is assumed to contain initial value data of the decoding process.

Since the TEK data is periodically changed to prevent decryption, the TEK data extraction block 34 includes the initial TEK data before and after the decoding process so that the communication between the central apparatus and the terminal apparatus is not interrupted when the TEK data is updated. A data storage buffer for storing in advance the index / sequence number of the TEK data set in the extension header among the value data and the delay TEK processing data (DDTK) is configured.

Hereinafter, the processing of the decoding block 30 will be described with reference to FIG. 14. Here, the MAC state information data (STMC) is at least, MAC data Encrypt signal generated by the Encrypt bit indicating whether the MAC data included in the extension header is encrypted, and enable indicating the position of the MAC header and address data (SA, DA) The signal and a TEK collation data enable signal indicating the position of the TEK collation data existing in the extension header are assumed to be included.

First, in the encryption presence check block 31, the encrypted portion and the unencrypted portion of the delay TEK processing data DDTK are determined by referring to the MAC state information data STMC, and the first decryption processing target data DD1. And out-of-decoding data DDX. That is, when the MAC data encrypt signal indicates that the MAC data is encrypted, the MAC header and the address data in the MAC data are output as the out-of-decryption data (DDX), and other MAC data is output to the first decoding process. It outputs as data DD1. On the other hand, when the MAC data encrypt signal does not indicate that the MAC data is encrypted, the entire MAC data is output as the out-of-decryption data DDX.

Thereafter, the first decoding processing target data DD1 is converted into 64 bits, which is the bit width of the decoding processing unit in the first bit conversion block 32, and output as the second decoding processing target data DD2.

Further, in the TEK contrast data extraction block 33, the TEK contrast data ITEK for selecting TEK data is extracted from the delay TEK processing data DDTK. That is, the data indicated by the TEK contrast data enable signal is extracted and output as TEK contrast data ITEK. In the TEK data extraction block 34, the TEK data TEK is extracted from the data storage buffer using the TEK reference data ITEK.

Thereafter, in the decoding processing block 35, decoding processing is performed using the second decoding processing target data DD2 and TEK data TEK, and the processing result is referred to as the first decoding processing result data RD1. .

Next, in the second bit conversion block 36, the first decoding result data RD1 is converted into 8 bits having the same bit width as the non-decoding data DDDX, and the second decoding result result data is converted. It outputs as (RD2). In the data combining block 37, the second decoding processing result data RD2 and the non-decoding data DDX are integrated and output as combined data CBD, and then in the third bit conversion block 38, The combined data CBD is converted into a bit width adapted to the data storage device 14, and the processing result is output to the data storage device 14 as TEK processing result data RTEK.

Here, 64 bits as the decoding processing unit and 8 bits as the bit width of the second decoding processing result data RD2 are not limited to the value and can be freely selected, for example, by 8 × n (n: integer) bits.

As described above, according to the present invention, in the digital bidirectional communication control apparatus in a bidirectional communication network constituted by a central apparatus and a plurality of terminal apparatuses, exclusive processing of the TEK function having a large computational throughput among the MAC functions is carried out. Execute as a processing block. As a result, the CPU load can be reduced, the circuit scale can be optimized, and the processing capacity is improved, thereby increasing the overall cost performance of the device.

Claims (13)

Apparatus for performing bidirectional control in digital bidirectional communication, An interface block for converting input downstream data to generate downstream data; A CPU for receiving data other than TEK (Traffic Encryption Key) processing data among the downlink data to realize a MAC (Media Access Control) function; A TEK processing block for receiving TEK processing data obtained from the downlink data, analyzing the data structure, and performing decoding processing based on the analysis result; The TEK processing block, MAC state information data indicating the state and meaning of MAC data which is data having a MAC structure by inputting TEK process data, analyzing the MPEG structure in the TEK process data and the MAC (Media Access Control) structure embedded in the MPEG structure. Digital two-way communication control device comprising a structural analysis block for outputting. The method of claim 1, The TEK processing block, And a decryption block for determining an encrypted portion of TEK processed data with reference to the MAC state information data, decrypting the encrypted portion using TEK data for decryption, and integrating the decryption result with an unencrypted portion. Digital two-way communication control device characterized in that. The method of claim 2, The structural analysis block, An MPEG header analysis block which analyzes an MPEG header which is an MPEG structure header in the TEK processing data, and outputs a MAC data position signal indicating the position of the MAC data and a MAC data head position signal indicating the head byte position of the MAC frame; The MAC data position signal and the MAC data head position signal are input to recognize the status information for fields other than the extension header and MACMM (MAC Management Message) header in the MAC header which are headers of the MAC structure, and at the same time, TEK processing. MAC header analysis block which outputs the extension header position information data indicating the position of the extension header when the header exists in the data, and outputs the MACMM header position information data indicating the position of the MACMM header when the MACMM header is present in the TEK processing data. and, An extension header analysis block which receives the extension header position information data, checks each field of the extension header, and outputs extension header state information data indicating state information of the extension header; A MACMM header analysis block which receives the MACMM header position information data, checks each field of the MACMM header, and outputs MACMM header status information data indicating the status information of the MACMM header, The MAC header analysis block, Receives the extended header state information data and the MACMM header state information data, each field state information other than the extended header and the MACMM header in the MAC header, the state information of the extended header indicated by the extended header state information data, and the MACMM header. And generating the MAC state information data based on the state information of the MACMM header indicated by the state information data. The method of claim 3, wherein The MPEG header analysis block is And checking the MAC data position and the leading byte position of the MAC frame by checking a field of the MPEG header, and outputting the MAC data position signal and the MAC data head position signal. The method of claim 3, wherein The MAC header analysis block, Digital two-way communication control device characterized in that for detecting the error of the MAC header by the HCS check. The method of claim 3, wherein The MAC header analysis block, To check the field indicating the MAC data length in the MAC header, The check is performed by calculating the data length of the MAC frame with reference to the MAC data head position signal, and determining whether the MAC frame length is equal to the sum of the value of the field and the predetermined data length. Digital two-way communication control device. The method of claim 3, wherein The MAC header analysis block, In addition to the HCS check, the MAC header length check and the extended header length check are used to perform error detection of the MAC header. And a check result by the HCS check is invalid when the check result by the MAC frame length check and the extended header length check is no error. The method of claim 3, wherein The extended header analysis block, Refer to the extension header position information data, check the field of the extension header, and determine the data length or type of the extension header, And if the field value of the extension header is invalid, recognizes that there is an error in the extension header, and outputs the contents as the extension header state information data. The method of claim 3, wherein The MACMM header analysis block, The MACMM header field information is checked with reference to the MACMM header location information data, and the data length and type of the MACMM are determined. And if the data value of the MACMM header field is invalid, recognizes that there is an error in the MACMM header, and outputs the contents as the MACMM header status information data. The method of claim 2, The decoding block, By referring to the MAC state information data, an encrypted portion and an unencrypted portion of the TEK processing data are selected, From the TEK processing data, TEK control data for selecting TEK data is extracted, With reference to the extracted TEK control data, TEK data to be used for decoding is selected from a plurality of TEK data previously held, Converts the encrypted part to the bit width of the decryption processing unit, decrypts it using the selected TEK data, Digital two-way communication control device characterized in that to integrate the data after decryption and the unencrypted portion. In a method of performing bidirectional control in digital bidirectional communication, Generating downstream data by format converting the input downstream data; Receiving, by the CPU, data other than the TEK (Traffic Encryption Key) processing data among the downlink data to realize a MAC (Media Access Control) function; A TEK processing step of receiving, by the TEK processing block, the TEK processing data obtained from the downlink data, analyzing the data structure, and performing decoding processing based on the analysis result; The TEK processing step, Analyze the MPEG structure in the TEK processed data and the MAC (Media Access Control) structure embedded in the MPEG structure, and have a structure analysis step of generating MAC state information data indicating the state and meaning of the MAC data which is the data having the MAC structure. Digital two-way communication control method characterized in that. The method of claim 11, The TEK processing step, A decryption step of determining an encrypted portion of the TEK processing data with reference to the MAC state information data, decrypting the encrypted portion using TEK data for decryption, and integrating the decryption result with the unencrypted portion; Digital two-way communication control method characterized in that. The method of claim 12, The structural analysis step, An MPEG header analysis step of analyzing an MPEG header, which is an MPEG structure header of TEK processing data, to generate a MAC data position signal indicating the position of the MAC data and a MAC data head position signal indicating the head byte position of the MAC frame; By using the MAC data position signal and the MAC data head position signal, status information is recognized for fields other than the extended header and MACMM (MAC Management Message) header in the MAC header, which are headers of the MAC structure, and TEK processing data. An MAC header analysis step of generating extended header location information data indicating the location of the extension header when the header exists in the header, and generating the MACMM header location information data indicating the location of the MACMM header when the MACMM header is present in the TEK processing data; , An extension header analysis step of receiving the extension header position information data and checking each field of the extension header to generate extension header state information data indicating the state information of the extension header; Receiving the MACMM header location information data and checking each field of the MACMM header, and generating a MACMM header status information data indicating the status information of the MACMM header; The status information of each field other than the extended header and MACMM header in the MAC header determined in the MAC header analysis step, the status information of the extended header indicated by the extended header status information data, and the MACMM header represented by the MACMM header status information data. And generating the MAC state information data based on the state information.

Images