KR20200021964A - Control apparatus for Distributed Control System with protection ability for impersonation attack and error of clock synchronization and clock synchronization method thereof - Google Patents

Abstract

The present invention relates to a control device for a distributed control system with a defense function for impersonation attacks and errors of clock synchronization and a clock synchronization method thereof. The defense function for the impersonation attacks and the errors of the clock synchronization is provided in the control device for the distributed control system so as to prevent control errors of the distributed control system, caused by malicious visual synchronization impersonation attacks or visual synchronization errors. Moreover, the control device for the distributed control system with the defense function for the impersonation attacks and the errors of the clock synchronization comprises a communication unit, a monitor unit, and a visual synchronization performance unit.

Description

Control apparatus for distributed control system with protection ability for impersonation attack and error of clock synchronization and clock synchronization method

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a time synchronization technology of a control device that performs control of a distributed control system, and more particularly, to a control device of a distributed control system having a time synchronization camouflage attack and an error protection function, and a method of time synchronization thereof.

Based on a pulse signal received every second period from an interrupt and an external synchronization device generated every first period by a timer of the system in the Republic of Korea Patent No. 10-1290785 (2013.07.23) registered in advance and registered by the applicant of the present invention The time synchronization device and method of the distributed control system including a correction reference calculation unit for calculating a correction reference and a correction unit for correcting the time of the system by using the calculated correction criteria.

The time synchronization of a distributed control system (DCS) applied to a nuclear power plant or the like is a time synchronization transmitted by a clock master device or a grand master device, which is a standard time synchronizer having accurate standard time. This is done by calibrating the internal time of the system based on the absolute signal.

In this case, the absolute signal for time synchronization may be a network time protocol (NTP) based time synchronization signal or / and a contact signal. Network time protocol (NTP) based time synchronization signals contain accurate standard time, and the contact signal is a periodic pulse signal.

Recently, the dual visual synchronization mechanism, which is a more advanced visual synchronization technique, is generally used. The redundant time synchronization mechanism is a technology for synchronizing system time using both network time protocol (NTP) based time synchronization signals and contact signals. In the case of the redundant time synchronization mechanism, a time jump occurs when an error occurs in any one of a network time protocol (NTP) based time synchronization signal or a contact signal.

If a malicious time synchronization spoofing attack or a time synchronization error that spoofs a network time protocol (NTP) based time synchronization signal or a contact signal occurs, serious problems may occur in the control of the distributed control system. In particular, when a distributed control system is applied to a dangerous facility such as a nuclear power plant, if the control of the distributed control system occurs due to a visual synchronization camouflage attack or a visual synchronization error, it may be fatal.

Therefore, the present inventors can prevent the control error of the distributed control system due to the malicious visual synchronization camouflage attack or the visual synchronization error by providing the visual synchronization camouflage attack and error defense functions, and thus enable stable distributed control system operation. We studied the control device of distributed control system with synchronous camouflage attack and error protection and its visual synchronization method.

Republic of Korea Patent No. 10-1290785 (2013.07.23)

The present invention can prevent the control error of the distributed control system due to malicious visual synchronization camouflage attack or visual synchronization error by providing a visual synchronization camouflage attack and error defense function, thereby enabling stable distributed control system operation. It is an object of the present invention to provide a control device of a distributed control system having attack and error protection functions and a method of visual synchronization thereof.

According to an aspect of the present invention for achieving the above object, the time synchronization of the control device of the distributed control system having a time-synchronized camouflage attack and error protection function is transmitted every set period from the standard time synchronizer having the correct standard time A communication unit for receiving an absolute signal; A monitoring unit for monitoring a continuous reception pattern of the time synchronization absolute signal received by the communication unit; Analyzes the continuous reception pattern of the time synchronization absolute signal monitored by the monitoring unit, and if no abnormality occurs in the continuous reception pattern of the time synchronization absolute signal for a certain number of times, the time synchronization of the control device is reflected by reflecting the absolute signal for time synchronization. If an abnormality occurs in the continuous reception pattern of the time synchronization absolute signal, the internal time of the control device is increased by ignoring the time synchronization absolute signal without performing the time synchronization by judging it as a time synchronization attack or a time synchronization error. It includes a time synchronization performing unit to be maintained continuously.

According to an additional aspect of the present invention, the time synchronization absolute signal may be a network time protocol (NTP) based time synchronization signal and a contact signal of the same or different periods.

According to an additional aspect of the present invention, when there is no new time synchronization absolute signal reception after a set period passes after the time synchronization execution unit receives the absolute time synchronization absolute signal, there is an abnormality in the continuous reception pattern of the time synchronization absolute signal. Judging that it occurred.

According to an additional aspect of the present invention, if a time difference between the time included in the network time protocol (NTP) based time synchronization signal and the controller internal time occurs, the continuous time of the absolute time signal is generated. It is determined that an abnormality has occurred in the reception pattern.

According to an additional aspect of the present invention, when the time synchronization unit performs a difference of more than the error time between the network time protocol (NTP) based time synchronization signal reception time and the contact signal reception time, continuous reception pattern of the absolute signal for time synchronization Judging that something wrong has occurred.

According to an additional aspect of the present invention, the time synchronization performing unit initially sets the synchronization mode of the control device to the abnormal mode, and counts the number of times that no abnormality occurs in the continuous reception pattern of the absolute signal for time synchronization through a counter. If no abnormality occurs in the continuous reception pattern of the time synchronization absolute signal for a specific number of times, change the synchronization mode of the controller to the normal mode.

According to an additional aspect of the present invention, when the synchronization mode of the control device is changed from the abnormal mode to the normal mode, the time synchronization of the control device is performed by reflecting the absolute signal for time synchronization.

According to an additional aspect of the present invention, the time synchronization performing unit performs time synchronization by reflecting an absolute signal for time synchronization transmitted every set period while the synchronization mode of the control apparatus is maintained in the normal mode.

According to an additional aspect of the present invention, if an error occurs in the continuous reception pattern of the absolute signal for time synchronization, the abnormal mode is continuously maintained when the synchronization mode of the control device is abnormal. If the sync mode is the normal mode, change to the abnormal mode.

According to an additional aspect of the present invention, when an error occurs in the continuous reception pattern of the absolute signal for time synchronization, the time synchronization performing unit initializes the counter.

According to another aspect of the present invention, the time synchronization method of a control device of a distributed control system having a time-synchronized camouflage attack and an error protection function is an absolute time synchronization transmitted at a set period from a standard time synchronizer having an accurate standard time. A signal receiving step of receiving a signal; A monitoring step of monitoring a continuous reception pattern of the time synchronization absolute signal received by the signal receiving step; A reception pattern analysis step of analyzing a continuous reception pattern of the time synchronization absolute signal monitored by the monitoring step to determine whether an abnormality occurs in the continuous reception pattern of the time synchronization absolute signal for a specific number of times; A vertical synchronization performing step of performing time synchronization of the control device by reflecting the absolute time synchronization signal when no abnormality occurs in the continuous reception pattern of the absolute time synchronization signal for a specific number of times as a result of the analysis by the reception pattern analysis step; As a result of the analysis by the reception pattern analysis step, when abnormality occurs in the continuous reception pattern of the time synchronization absolute signal, it is judged as a time synchronization attack or a time synchronization error and is controlled by ignoring the time synchronization absolute signal without performing time synchronization. Ignoring the time synchronization so that the internal time of the device is maintained.

According to an additional aspect of the present invention, when there is no new time synchronization absolute signal reception after the set period after receiving the previous time synchronization absolute signal in the reception pattern analysis step, the abnormal reception pattern of the time synchronization absolute signal is abnormal. Judging this has occurred.

According to an additional aspect of the present invention, when the difference between the time included in the network time protocol (NTP) based time synchronization signal in the reception pattern analysis step and the error time more than the error time, the continuation of the time synchronization absolute signal It is determined that an abnormality has occurred in the reception pattern.

According to an additional aspect of the present invention, continuous reception of an absolute signal for time synchronization when a difference in error time or more occurs between a network time protocol (NTP) based time synchronization signal reception time and a contact signal reception time in a reception pattern analysis step. It is determined that an abnormality has occurred in the pattern.

The present invention can effectively prevent the control error of the distributed control system due to malicious time-synchronized camouflage attacks and time-synchronization errors, thereby enabling stable distributed control system operation.

Figure 1 is a block diagram showing the configuration of an embodiment of a control device of a distributed control system having a visual synchronization camouflage attack and error protection function according to the present invention.
2 is a block diagram illustrating an embodiment of a time synchronization performing unit of a control device of a distributed control system having a time synchronization camouflage attack and error protection function according to the present invention.
3 is a flowchart illustrating an example of a time synchronization operation of a control device of a distributed control system having a time synchronization camouflage attack and error protection function according to the present invention.
4 is a diagram illustrating a network time protocol (NTP) based time synchronization signal and a contact signal received in the same period.
FIG. 5 is a flowchart illustrating a configuration of an embodiment of a time synchronization method of a control device of a distributed control system having a time synchronization camouflage attack and error protection function according to the present invention.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily understand and reproduce. Although specific embodiments are illustrated in the drawings and related detailed description is described, it is not intended to limit the various embodiments of the present invention to a specific form.

In the following description of the present invention, when it is determined that detailed descriptions of related known functions or configurations may unnecessarily obscure the gist of the embodiments of the present invention, the detailed description thereof will be omitted.

When a component is said to be "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but it may be understood that another component may be present in the middle. Should be.

On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that there is no other component in between.

Figure 1 is a block diagram showing the configuration of an embodiment of a control device of a distributed control system having a visual synchronization camouflage attack and error protection function according to the present invention. As shown in FIG. 1, the control device 100 of the distributed control system having the visual synchronization camouflage attack and error protection function according to this embodiment is a communication unit 110 implemented in software or hardware or a combination of both. And a monitoring unit 120 and a time synchronization performing unit 130.

The communication unit 110 receives an absolute signal for time synchronization transmitted every set period from the standard time synchronizer 200 having the correct standard time. For example, the communication unit 110 may be implemented to receive an absolute signal for time synchronization in a wireless communication scheme such as Ethernet based wired communication or Bluetooth.

At this time, the standard time synchronizing device having an accurate standard time may be a clock master device or a grand master device having an accurate standard time as a reference for time synchronization.

Meanwhile, the absolute signal for time synchronization may be a network time protocol (NTP) based time synchronization signal or / and a contact signal. Network time protocol (NTP) based time synchronization signals contain accurate standard time, and the contact signal is a periodic pulse signal that indicates to start time synchronization.

For example, the control apparatus 100 of the distributed control system having the time-synchronized camouflage attack and error protection function according to the present invention may be implemented to synchronize the time of the distributed control system using a redundant time synchronization mechanism. The dual time synchronization mechanism is a technology that synchronizes system time by using network time protocol (NTP) based time synchronization signals and contact signals simultaneously.

The monitoring unit 120 monitors the continuous reception pattern of the time synchronization absolute signal received by the communication unit 110. For example, the monitoring unit 120 may be implemented to monitor a continuous reception pattern of the time synchronization absolute signal by checking whether the time synchronization absolute signal is properly received every set period.

Specifically, the standard time synchronizer 200 having the correct standard time is set to simultaneously transmit the network time protocol based time synchronization signal and the contact signal in the same period, and the monitoring unit 120 is based on the network time protocol of the same or different period. It can be implemented to monitor the continuous reception pattern of the absolute signal for time synchronization by confirming that the time synchronization signal and the contact signal are properly received every set period.

If a malicious time-synchronized camouflage attack or time-synchronization error that masquerades Network Time Protocol (NTP) based time synchronization signals or contact signals occurs, serious problems may occur in the control of distributed control systems applied to hazardous facilities such as nuclear power plants, If an abnormality occurs in the control of the distributed control system, it can only be fatal, so that the monitoring unit 120 monitors the continuous reception pattern of the absolute signal for time synchronization and uses it for malicious time synchronization camouflage attack or time synchronization error determination. .

The time synchronization performing unit 130 analyzes the continuous reception pattern of the time synchronization absolute signal monitored by the monitoring unit 120, and if no abnormality occurs in the continuous reception pattern of the time synchronization absolute signal for a specific number of times, the time synchronization is performed. Time synchronization of the controller is performed by reflecting the absolute signal.

If no abnormality occurs in the continuous reception pattern of the time synchronization absolute signal for a certain number of times, it means that the time synchronization absolute signal is received without error every set period. Therefore, the time synchronization performing unit 130 performs time synchronization of the control device by reflecting the absolute signal for time synchronization.

At this time, the time synchronization may be achieved by roughly correcting the internal time of the distributed control system using the accurate standard time included in the Network Time Protocol (NTP), and then precisely correcting it using the contact signal. Since this time synchronization technique is a conventional matter that is variously known before this application, a detailed description thereof will be omitted.

On the other hand, if an abnormality occurs in the continuous reception pattern of the time synchronization absolute signal, the time synchronization performing unit 130 judges that the time synchronization error or time synchronization error does not perform the time synchronization and ignores the time synchronization absolute signal. This allows the internal time of the control unit to be maintained.

For example, when the time synchronization performing unit 130 does not receive a new time synchronization absolute signal such that a set period passes after the previous time synchronization absolute signal is received, it is determined that an abnormality has occurred in the continuous reception pattern of the time synchronization absolute signal. It can be implemented to.

For example, when a time difference between the time included in the network time protocol (NTP) based time synchronization signal and the internal time of the controller is greater than the error time, the time synchronization execution unit 130 may generate a continuous reception pattern of the absolute signal for time synchronization. It may be implemented to determine that an abnormality has occurred.

For example, when the time synchronization performing unit 130 experiences a difference of more than an error time between a network time protocol (NTP) based time synchronization signal reception time and a contact signal reception time, an error occurs in the continuous reception pattern of the absolute signal for time synchronization. It can be implemented to determine that it has occurred. 4 is a diagram illustrating a network time protocol (NTP) based time synchronization signal and a contact signal received in the same period.

An abnormality in the continuous reception pattern of the time synchronization absolute signal means that the time synchronization absolute signal is not received at every set period or is included in the network time protocol (NTP) based time synchronization signal and the internal time of the controller. This means that there is more than error time difference between the time or the time difference between network time protocol (NTP) based time synchronization signal reception time and contact signal reception time. The visual synchronization performing unit 130 ignores the absolute signal for time synchronization.

As a result, time synchronization is not achieved, and the internal time of the control unit of the distributed control system is maintained, thereby preventing malicious time synchronization spoofing attacks or time synchronization errors that impersonate network time protocol (NTP) based time synchronization signals or contact signals. The control error of the distributed control system can be effectively prevented, thereby enabling stable distributed control system operation.

2 is a block diagram illustrating an embodiment of a time synchronization performing unit of a control device of a distributed control system having a time synchronization camouflage attack and error protection function according to the present invention. As shown in FIG. 2, the time synchronization performing unit 130 includes a counter 131, a pattern analyzing unit 132, an abnormality detecting unit 133, a time synchronization processing unit 134, and a time synchronization disregarding unit. (135).

The counter 131 counts the number of times of receiving the absolute signal for time synchronization. For example, each time the counter 131 receives an absolute signal for time synchronization, the counter 131 may increase the number from 0 to one, and then initialize the counter 131 when an abnormality occurs in the continuous reception pattern of the time synchronization absolute signal.

The pattern analyzer 132 analyzes the continuous reception pattern of the time synchronization absolute signal. For example, the pattern analyzer 132 analyzes whether the number of receptions of the time synchronization absolute signal counted by the counter 131 reaches a predetermined number of times at a predetermined period.

The abnormality detector 133 detects whether an abnormality occurs in a continuous reception pattern of the absolute signal for time synchronization for a specific number of times based on the pattern analysis result by the pattern analyzer 132.

At this time, the abnormality detecting unit 133 does not receive an absolute signal for time synchronization at every set period, or there is a difference in error time or more between the time included in the network time protocol (NTP) based time synchronization signal and the internal time of the controller. Or when a difference in error time or more occurs between the NTP based time synchronization signal reception time and the contact signal reception time, it may be implemented to detect an abnormality in the continuous reception pattern of the absolute signal for time synchronization. .

If the abnormality detecting unit 133 detects that no abnormality has occurred in the continuous reception pattern of the absolute signal for time synchronization for a specific number of times, the time synchronization processing unit 134 reflects the absolute signal for time synchronization and visually synchronizes the control device. To process

When the abnormality detection unit 133 detects that an abnormality has occurred in the continuous reception pattern of the absolute signal for time synchronization, the time synchronization ignore unit 135 determines that the time synchronization camouflage attack or time synchronization error does not perform the time synchronization. And by ignoring the absolute signal for time synchronization, the internal time of the controller is maintained.

By implementing in this way, the present invention can effectively prevent the control error of the distributed control system due to malicious visual synchronization camouflage attack or visual synchronization error, thereby enabling stable distributed control system operation.

On the other hand, according to an additional aspect of the invention, the time synchronization performing unit 130 initially sets the synchronization mode of the control device to the abnormal mode, and the number of times that no abnormality occurs in the continuous reception pattern of the absolute signal for time synchronization Counting through the counter, if the abnormality does not occur in the continuous reception pattern of the absolute signal for time synchronization for a certain number of times, it can be implemented to change the synchronization mode of the control device to the normal mode.

In this case, when the synchronization mode of the control device is changed from the abnormal mode to the normal mode, the time synchronization unit 130 may be implemented to perform the time synchronization of the control device by reflecting the absolute signal for time synchronization. On the other hand, when the synchronization mode of the control device is changed from the abnormal mode to the normal mode, it may be implemented to initialize the counter.

That is, in this embodiment, if no abnormality occurs in the continuous reception pattern of the time synchronization absolute signal for a specific number of times while the synchronization mode of the controller is initially set to the abnormal mode, the synchronization mode is changed from the abnormal mode to the normal mode. In this case, the time synchronization of the controller is performed by reflecting the absolute signal for time synchronization.

Meanwhile, according to an additional aspect of the present invention, the time synchronization performing unit 130 may be implemented to perform time synchronization by reflecting the absolute signal for time synchronization transmitted every set period while the synchronization mode of the control device is maintained in the normal mode. Can be.

That is, in this embodiment, an abnormality occurs in the continuous reception pattern of the absolute signal for time synchronization while the synchronization mode of the control device remains in the normal mode while the synchronization mode of the control device is changed from the abnormal mode to the normal mode. Otherwise, time synchronization is performed by reflecting the absolute signal for time synchronization transmitted every set period.

On the other hand, according to an additional aspect of the present invention, if the time synchronization performing unit 130 has an abnormality in the continuous reception pattern of the absolute signal for time synchronization, if the synchronization mode of the control device is an abnormal mode, the abnormal mode is continuously maintained. In addition, when the synchronous mode of the control device is a normal mode, it may be implemented to change to an abnormal mode. In this case, when an error occurs in the continuous reception pattern of the absolute signal for time synchronization, the time synchronization performing unit 130 may be implemented to initialize the counter.

That is, in this embodiment, when an abnormality occurs in the continuous reception pattern of the absolute signal for time synchronization, the time synchronization is prevented from being performed by keeping the control mode in the abnormal mode or changing to the abnormal mode. Is initialized to determine whether the continuous reception pattern of the time synchronization absolute signal that has occurred is returned to normal.

The time synchronization process performed by the time synchronization performing unit 130 will be described in more detail with reference to FIG. 2. 3 is a flowchart illustrating an example of a time synchronization operation of a control device of a distributed control system having a time synchronization camouflage attack and error protection function according to the present invention.

Referring to FIG. 3, it can be seen that the time synchronization performing unit 130 initially sets the synchronization mode of the control device to the abnormal mode in step 310. The reason for setting the synchronous mode of the control device to the initial abnormal mode is to suspend the time synchronization of the control device until checking whether the synchronous mode of the control device is the normal mode.

In operation 320, the time synchronization performing unit 130 may determine whether an abnormality occurs in the continuous reception pattern of the absolute signal for time synchronization. At this time, whether the abnormality occurs in the continuous reception pattern of the time synchronization absolute signal is performed in the following three steps.

First, in step 321, if there is no new time synchronization absolute signal received after the set period after the previous time synchronization absolute signal reception, the abnormality in the continuous reception pattern of the time synchronization absolute signal. Judging that it occurred.

Next, in step 322, when the time synchronization unit 130 includes the time included in the network time protocol (NTP) based time synchronization signal and the difference between the error time or more occurs, the continuation of the time synchronization absolute signal occurs. It is determined that an abnormality has occurred in the reception pattern.

Then, in step 323, when the time synchronization performing unit 130 experiences a difference of more than the error time between the network time protocol (NTP) based time synchronization signal reception time and the contact signal reception time, continuous reception of the absolute time synchronization signal. It is determined that an abnormality has occurred in the pattern.

On the other hand, when an abnormality occurs in the continuous reception pattern of the time synchronization absolute signal, the time synchronization performing unit 130 maintains the abnormal mode when the synchronization mode of the control device is the abnormal mode in step 330. If the sync mode is the normal mode, change to the abnormal mode. Then, the time synchronization execution unit 130 initializes the counter.

On the other hand, if no abnormality occurs in the continuous reception pattern of the time synchronization absolute signal, the time synchronization execution unit 130 determines whether the synchronization mode of the control device is the normal mode in step 340, and if the normal mode is In operation 350, time synchronization is performed by reflecting the absolute signal for time synchronization, and in the abnormal mode, time synchronization is not performed.

As in step 360, the number of times no abnormality occurs in the continuous reception pattern of the time synchronization absolute signal is counted through a counter, and if no abnormality occurs in the continuous reception pattern of the time synchronization absolute signal for a specific number of times, At 370, the synchronous mode of the control device is changed to the normal mode and returns to step 320.

Accordingly, while the synchronization mode of the control device is the abnormal mode (when an abnormality occurs in the continuous reception pattern of the absolute signal for visual synchronization), the time synchronization of the control device is not performed, and the synchronization mode of the control device is normal for a certain number of times. Control of the distributed control system by malicious visual synchronization camouflage attacks or visual synchronization errors by performing time synchronization of the control device only when the mode (when no abnormality occurs in the continuous reception pattern of the absolute signal for visual synchronization) is maintained. The error can be effectively prevented.

The time synchronization method of the control apparatus of the distributed control system with a time-synchronized camouflage attack and error protection function according to the present invention as described above will be described with reference to FIG.

FIG. 5 is a flowchart illustrating a configuration of an embodiment of a time synchronization method of a control device of a distributed control system having a time synchronization camouflage attack and error protection function according to the present invention.

As shown in FIG. 5, the time synchronization method of the control apparatus of the distributed control system having the time-synchronized camouflage attack and error protection function according to the present invention includes a signal reception step 510, a monitoring step 520, and a reception step. The pattern analysis step 530, the angle synchronization performing step 540, and the time synchronization disregarding step 550 are included.

In the signal receiving step 510, the control device of the distributed control system having a time synchronization camouflage attack and error protection function receives an absolute signal for time synchronization transmitted every set period from a standard time synchronization device having an accurate standard time.

At this time, the standard time synchronizing device having an accurate standard time may be a clock master device or a grand master device having an accurate standard time as a reference for time synchronization.

Meanwhile, the absolute signal for time synchronization may be a network time protocol (NTP) based time synchronization signal or / and a contact signal. Network time protocol (NTP) based time synchronization signals contain accurate standard time, and the contact signal is a periodic pulse signal that indicates to start time synchronization.

In the monitoring step 520, the control device of the distributed control system having the time synchronization camouflage attack and error protection function monitors the continuous reception pattern of the time synchronization absolute signal received by the signal reception step 510.

For example, the monitoring step 520 may be implemented to monitor a continuous reception pattern of the time synchronization absolute signal by checking whether the time synchronization absolute signal is properly received at each set period.

Specifically, the standard time synchronizer having the correct standard time is set to simultaneously transmit the network time protocol based time synchronization signal and the contact signal in the same period, and in the monitoring step 520, the network time protocol based time synchronization signal of the same or different periods. And monitoring the continuous reception pattern of the absolute signal for time synchronization by checking whether the contact signal is properly received every set period.

If a malicious time-synchronized camouflage attack or time-synchronization error that masquerades Network Time Protocol (NTP) based time synchronization signals or contact signals occurs, serious problems may occur in the control of distributed control systems applied to hazardous facilities such as nuclear power plants, If an abnormality occurs in the control of the distributed control system, it can only be fatal. In the monitoring step 520, the continuous reception pattern of the absolute signal for time synchronization is monitored to be used for malicious time synchronization camouflage attack or time synchronization error determination.

In the reception pattern analysis step 530, the control device of the distributed control system having the visual synchronization camouflage attack and error protection functions analyzes the continuous reception pattern of the absolute signal for time synchronization monitored by the monitoring step 520 for a specific number of times. It is determined whether an abnormality occurs in the continuous reception pattern of the absolute signal for time synchronization.

For example, in the reception pattern analysis step 530, if there is no new time synchronization absolute signal reception after a set period passes after receiving the previous time synchronization absolute signal, it is determined that an abnormality has occurred in the continuous reception pattern of the time synchronization absolute signal. It can be implemented to.

For example, if a difference between the time included in the network time protocol (NTP) based time synchronization signal in the reception pattern analysis step 530 and an error time or more occurs between the internal time of the controller, the continuous reception pattern of the absolute signal for time synchronization occurs. It may be implemented to determine that an abnormality has occurred.

For example, in the reception pattern analysis step 530, if there is a difference in error time or more between the network time protocol (NTP) based time synchronization signal reception time and the contact signal reception time, an abnormality occurs in the continuous reception pattern of the absolute signal for time synchronization. It can be implemented to determine that it has occurred.

As a result of the analysis by the reception pattern analysis step 530 in the angle synchronization performing step 540, if there is no abnormality in the continuous reception pattern of the absolute signal for time synchronization for a specific number of times, the visual synchronization camouflage attack and error protection function is provided. A control device of a distributed control system reflects the absolute signal for time synchronization to perform time synchronization of the control device.

If no abnormality occurs in the continuous reception pattern of the time synchronization absolute signal for a certain number of times, it means that the time synchronization absolute signal is received without error every set period. Therefore, in the vertical synchronization performing step 540, the time synchronization of the controller is performed by reflecting the absolute signal for time synchronization.

At this time, the time synchronization may be achieved by roughly correcting the internal time of the distributed control system using the accurate standard time included in the Network Time Protocol (NTP), and then precisely correcting it using the contact signal. Since this time synchronization technique is a conventional matter that is variously known before this application, a detailed description thereof will be omitted.

If the abnormality occurs in the continuous reception pattern of the absolute signal for time synchronization as a result of the analysis by the reception pattern analysis step 530 in the time synchronization disregarding step 550, a distributed control system having a time synchronization camouflage attack and an error protection function. The controller determines that it is a visual synchronization camouflage attack or a visual synchronization error, so that the internal time of the controller is maintained by ignoring the absolute signal for visual synchronization without performing the visual synchronization.

An abnormality in the continuous reception pattern of the time synchronization absolute signal means that the time synchronization absolute signal is not received at every set period or is included in the network time protocol (NTP) based time synchronization signal and the internal time of the controller. This means that there is more than error time difference between the time or the time difference between network time protocol (NTP) based time synchronization signal reception time and contact signal reception time. In operation 550, the absolute signal for time synchronization is ignored.

As a result, time synchronization is not achieved, and the internal time of the control unit of the distributed control system is maintained, thereby preventing malicious time synchronization spoofing attacks or time synchronization errors that impersonate network time protocol (NTP) based time synchronization signals or contact signals. The control error of the distributed control system can be effectively prevented, thereby enabling stable distributed control system operation.

As described above, the present invention can effectively prevent the control error of the distributed control system due to malicious visual synchronization camouflage attack or visual synchronization error, and the stable distributed control system can be operated. Can achieve the purpose.

The various embodiments disclosed in the specification and drawings are merely presented as specific examples for clarity and are not intended to limit the scope of the various embodiments of the present invention.

Accordingly, the scope of various embodiments of the present invention includes all changes or modifications derived based on the technical spirit of the various embodiments of the present invention in addition to the embodiments described herein are included in the scope of the various embodiments of the present invention. Should be interpreted as

The present invention can be used industrially in the field of time synchronization technology and its application technology of the control device for performing the control of the distributed control system.

100: control device of distributed control system
110: communication unit
120: monitoring unit
130: time synchronization unit
131: Counter
132: pattern analysis unit
133: abnormal detection unit
134: time synchronization processor
135: ignore visual synchronization
200: standard time synchronizer

Claims (15)

A communication unit which receives an absolute signal for time synchronization transmitted every set period from a standard time synchronizing device having an accurate standard time;
A monitoring unit for monitoring a continuous reception pattern of the time synchronization absolute signal received by the communication unit;
Analyzes the continuous reception pattern of the time synchronization absolute signal monitored by the monitoring unit, and if no abnormality occurs in the continuous reception pattern of the time synchronization absolute signal for a certain number of times, the time synchronization of the control device is reflected by reflecting the absolute signal for time synchronization. If an abnormality occurs in the continuous reception pattern of the time synchronization absolute signal, the internal time of the controller is increased by ignoring the time synchronization absolute signal without performing the time synchronization by judging it as a time synchronization camouflage attack or a time synchronization error. A visual synchronization performing unit to be maintained continuously;
Control device of a distributed control system having a visual synchronization camouflage attack and error protection function comprising. The method of claim 1,
The absolute signal for visual synchronization is:
A control device of a distributed control system having a time synchronization spoofing attack and an error protection function that is a time synchronization signal and a contact signal based on a network time protocol (NTP) based on the same or different periods. The method of claim 2,
Visual Synchronization Performer:
If there is no new time synchronization absolute signal after a set period has passed since the previous time synchronization absolute signal reception, the function of visual synchronization camouflage attack and error protection that judges that an abnormality in the continuous reception pattern of the time synchronization absolute signal has occurred. Control device of the distributed control system provided. The method of claim 2,
Visual Synchronization Performer:
A time-synchronized camouflage attack that judges that an abnormality has occurred in the continuous reception pattern of the time-synchronized absolute signal when a time difference between the time included in the network time protocol (NTP) -based time synchronization signal and the internal time of the controller occurs. And a control device of a distributed control system having an error protection function. The method of claim 2,
Visual Synchronization Performer:
Visual synchronization camouflage attack and error that judges that there is an abnormality in the continuous reception pattern of the absolute signal for time synchronization when there is a difference in error time between the network time protocol (NTP) based time synchronization signal reception time and the contact signal reception time. Control device of a distributed control system with defense function. The method according to any one of claims 1 to 5,
Visual Synchronization Performer:
Initially, the synchronization mode of the controller is set to the abnormal mode, and the number of times that no abnormality occurs in the continuous reception pattern of the absolute signal for time synchronization is counted through a counter, so that continuous reception of the absolute signal for time synchronization for a specific number of times is performed. The control apparatus of the distributed control system provided with the time-synchronizing camouflage attack and error protection function which changes a synchronous mode of a control apparatus to a normal mode, when an abnormality does not occur in a pattern. The method of claim 6,
Visual Synchronization Performer:
When the synchronization mode of the control device is changed from the abnormal mode to the normal mode, the control device of the distributed control system having a time synchronization camouflage attack and error protection function to perform the time synchronization of the control device by reflecting the absolute signal for time synchronization. The method of claim 7, wherein
Visual Synchronization Performer:
A control device of a distributed control system having a time synchronization camouflage attack and error protection function, which performs time synchronization by reflecting an absolute signal for time synchronization transmitted every set period while the synchronization mode of the controller is maintained in the normal mode. The method of claim 6,
Visual Synchronization Performer:
If an abnormality occurs in the continuous reception pattern of the time synchronization absolute signal, the abnormal mode is maintained if the synchronous mode of the control device is abnormal, and the abnormal mode is changed if the synchronous mode of the control device is normal. Control device of distributed control system with visual synchronous camouflage attack and error protection. The method of claim 9,
Visual Synchronization Performer:
The control apparatus of the distributed control system provided with the time-synchronizing camouflage attack and error-protection function which initializes a counter, when an abnormality occurs in the continuous reception pattern of the time synchronization absolute signal. A signal receiving step of receiving an absolute signal for time synchronization transmitted every set period from a standard time synchronizing device having an accurate standard time;
A monitoring step of monitoring a continuous reception pattern of the time synchronization absolute signal received by the signal receiving step;
A reception pattern analysis step of analyzing a continuous reception pattern of the time synchronization absolute signal monitored by the monitoring step to determine whether an abnormality occurs in the continuous reception pattern of the time synchronization absolute signal for a specific number of times;
A vertical synchronization performing step of performing time synchronization of the control device by reflecting the absolute time synchronization signal when no abnormality occurs in the continuous reception pattern of the absolute time synchronization signal for a specific number of times as a result of the analysis by the reception pattern analysis step;
As a result of the analysis by the reception pattern analysis step, when abnormality occurs in the continuous reception pattern of the time synchronization absolute signal, it is judged as a time synchronization attack or a time synchronization error and is controlled by ignoring the time synchronization absolute signal without performing time synchronization. Disregarding time synchronization such that the internal time of the device is maintained;
A visual synchronization method of a control device of a distributed control system having a visual synchronization camouflage attack and error protection function. The method of claim 11,
The absolute signal for visual synchronization is:
A time synchronization method of a control device of a distributed control system having a time synchronization spoofing attack and an error protection function that is a time synchronization signal and a contact signal based on a network time protocol (NTP) based on the same or different periods. The method of claim 12,
At the receiving pattern analysis stage:
If there is no new time synchronization absolute signal after a set period has passed since the previous time synchronization absolute signal reception, the function of visual synchronization camouflage attack and error protection that judges that an abnormality in the continuous reception pattern of the time synchronization absolute signal has occurred. A time synchronization method of a control device of a distributed control system. The method of claim 12,
At the receiving pattern analysis stage:
A time-synchronized camouflage attack that judges that an abnormality has occurred in the continuous reception pattern of the time-synchronized absolute signal when a time difference between the time included in the network time protocol (NTP) -based time synchronization signal and the internal time of the controller occurs. And a visual synchronization method of a control device of a distributed control system having an error protection function. The method of claim 12,
At the receiving pattern analysis stage:
Visual synchronization camouflage attack and error that judges that there is an abnormality in the continuous reception pattern of the absolute signal for time synchronization when there is a difference in error time between the network time protocol (NTP) based time synchronization signal reception time and the contact signal reception time. A time synchronization method of a control device of a distributed control system having a defense function.

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