JP7079710B2 - Unauthorized communication prevention system and unauthorized communication prevention method - Google Patents

Description

The present invention relates to an unauthorized communication prevention system and an unauthorized communication prevention method for preventing unauthorized establishment of authentication communication.

Conventionally, a distance measuring system that communicates radio waves between a terminal and its communication partner, measures the distance between them, and determines the validity of the measured distance is well known (see Patent Document 1 and the like). It is considered that this type of ranging system will be used as an unauthorized communication prevention system that sets the validity / invalidity of communication based on the judgment result of whether or not the measured value calculated through radio communication between two parties is appropriate. Has been done. The fraudulent communication prevention system obtains a measured value according to the distance between the terminal and its communication partner, for example, and when it is determined that the measured value is appropriate (within a predetermined range), for example, wirelessly between the two parties. Allows the execution of ID verification to be established. This makes it possible to operate the communication partner with the terminal.

Japanese Unexamined Patent Publication No. 2014-227647

In this main unauthorized communication prevention system, there was a need to accurately detect unauthorized communication.
An object of the present invention is to provide an unauthorized communication prevention system and an unauthorized communication prevention method capable of ensuring the determination accuracy of communication being unauthorized communication.

An unauthorized communication prevention system that solves the above problems obtains a measured value according to the distance between the first communication device and the second communication device when communication is established between the first communication device and the second communication device, and based on the measured value. In addition, a determination unit that determines whether the communication between the two parties is regular communication or unauthorized communication, a confirmation unit that confirms whether or not the determination result determined to be unauthorized communication occurs multiple times, and unauthorized communication. When the determination result determined to be is generated a plurality of times, as a countermeasure against the unauthorized communication, a control unit that controls communication when the first communication device and the second communication device perform wireless authentication is provided. Prepared.

According to this configuration, when the determination result that the communication is unauthorized communication is detected multiple times, the communication when the first communication device and the second communication device perform wireless authentication is controlled to be appropriate for the unauthorized communication. Take appropriate action. In this way, when the determination result that the communication is unauthorized communication is detected multiple times, it is advantageous to determine the determination result of the presence of unauthorized communication and take measures to accurately determine the unauthorized communication. Will be. Therefore, it is possible to secure the determination accuracy that the communication is unauthorized communication.

In the unauthorized communication prevention system, the confirmation unit confirms whether or not the determination results determined to be unauthorized communication are continuous, and the control unit determines whether the determination results determined to be unauthorized communication are continuous. , It is preferable to take measures against the unauthorized communication. According to this configuration, it is possible to take measures against unauthorized communication in a situation where there is a high possibility that a third party will illegally shift the communication to establishment.

In the unauthorized communication prevention system, it is preferable that the confirmation unit causes the control unit to take measures against the unauthorized communication when the determination result in which the measured value is extremely unreasonable is detected a plurality of times. According to this configuration, it is possible to take measures against unauthorized communication in a situation where there is a high possibility that unauthorized communication by a third party is being attempted.

In the fraudulent communication prevention system, the confirmation unit uses the measured value and an index value different from the measured value, and a determination result of being determined to be fraudulent communication is obtained a plurality of times from a composite judgment of these values. It is preferable to confirm whether or not it occurs. According to this configuration, it is advantageous to accurately determine whether the communication is regular communication or unauthorized communication.

In the fraudulent communication prevention system, the determination unit causes one of the first communication device and the second communication device to transmit a plurality of radio waves by changing channels, and the determination unit is based on the phase difference of the radio waves of each channel. It is preferable to obtain the measured value and determine from the measured value whether the communication between the two parties is regular communication or unauthorized communication. According to this configuration, when radio waves are transmitted on multiple channels and the normality / invalidity of communication is determined based on the measured value obtained from the phase difference of the radio waves of each channel, if an attempt is made to establish this communication illegally, the radio waves It is necessary to falsify the phase information, but with random falsification, it can be said that the probability that unauthorized communication will be established is low. Therefore, when an unauthorized communication is attempted, there is a high possibility that the unauthorized communication is repeated many times, and the number of times that the normal / illegal determination result becomes the unauthorized communication increases. It can be said that this is highly effective in detecting unauthorized communication without omission when confirming the correctness of communication using the determination logic of this example.

The method for preventing unauthorized communication that solves the above problems is to obtain a measured value according to the distance between the first communication device and the second communication device when communication is established between the first communication device and the second communication device, and based on the measured value. In addition, there is a step of determining whether the communication between the two parties is regular communication or unauthorized communication, a step of confirming whether or not the determination result determined to be unauthorized communication occurs multiple times, and unauthorized communication. When the determination result determined to be is generated a plurality of times, as a countermeasure against the unauthorized communication, a step of controlling communication when the first communication device and the second communication device perform wireless authentication is provided.

According to the present invention, it is possible to ensure the accuracy of determining that the communication is unauthorized communication.

The block diagram of the electronic key system of one Embodiment. Schematic diagram of the unauthorized communication prevention system. A concrete configuration diagram of the unauthorized communication prevention system. A flowchart executed when determining whether it is regular communication or unauthorized communication. An example diagram of unauthorized communication by radio wave relay. An explanatory diagram showing a specific communication determination logic. The schematic diagram which shows the normal / invalidity judgment logic of another example of communication.

Hereinafter, an embodiment of the unauthorized communication prevention system and the unauthorized communication prevention method will be described with reference to FIGS. 1 to 6.
As shown in FIG. 1, the vehicle 1 includes an electronic key system 4 that wirelessly collates an ID with a terminal 2 to execute or permit the operation of the in-vehicle device 3. The electronic key system 4 is a key operation-free system that executes ID collation (smart collation) with the terminal 2 by narrow-range radio in the wake of communication from the vehicle 1. The in-vehicle device 3 includes, for example, a door lock device 5 and an engine 6. The terminal 2 is a terminal having a key function, a so-called electronic key.

The vehicle 1 includes a collation ECU (Electronic Control Unit) 7 for ID collation, a body ECU 8 for managing the power supply of vehicle-mounted electrical components, and an engine ECU 9 for controlling the engine 6. These ECUs are electrically connected via a communication line 10 in the vehicle. In the memory (not shown) of the collation ECU 7, the key ID of the terminal 2 registered in the vehicle 1 and the key unique key used at the time of authentication of ID collation are registered. The body ECU 8 controls a door lock device 5 that switches the lock / unlock of the vehicle door 11.

The vehicle 1 includes a communication unit 12 that executes communication in the vehicle 1. The communication unit 12 executes communication with the terminal 2 by, for example, LF (Low Frequency) -UHF (Ultra High Frequency) bidirectional communication (smart communication). In this case, the communication from the vehicle 1 to the terminal 2 is preferably LF communication, and the communication from the terminal 2 to the vehicle 1 is preferably UHF communication.

The terminal 2 includes a terminal control unit 15 that controls the operation of the terminal 2 and a communication unit 16 that executes communication at the terminal 2. The communication unit 16 executes wireless communication with the communication unit 12 of the vehicle 1 through the narrow range radio. The unique key ID and key unique key of the terminal 2 are written and stored in the memory (not shown) of the terminal control unit 15.

The vehicle 1 periodically transmits a wake signal from the communication unit 12 by LF in order to activate the terminal 2 in the standby state. When the communication unit 16 receives the wake signal transmitted from the communication unit 12, the terminal 2 switches from the standby state to the activation state, and UHF transmits the ack signal from the communication unit 16 to the vehicle 1. When the collation ECU 7 receives the AC signal transmitted from the terminal 2 by the communication unit 12 and recognizes the establishment of communication, the collation ECU 7 executes ID collation (smart collation). Smart verification includes key ID verification for confirming the correctness of the key ID registered in the terminal 2, challenge response authentication using a predetermined encryption key, and the like.

When the collation ECU 7 establishes communication with the terminal 2 located outdoors, the collation ECU 7 executes smart collation (outdoor smart collation) with the terminal 2. The establishment of smart collation (outdoor smart collation) with the terminal 2 located outdoors is one condition for permitting or executing the operation of the door lock device 5 by the body ECU 8. When the collation ECU 7 establishes communication with the terminal 2 located in the room, the collation ECU 7 executes smart collation (indoor smart collation) with the terminal 2. The establishment of smart collation with the terminal 2 located in the room (indoor smart collation) is one of the conditions for permitting the transition operation of the vehicle power supply (starting operation of the engine 6).

As shown in FIG. 2, the vehicle 1 and the terminal 2 are provided with a function (illegal communication prevention system 19) for determining the normality / illegality of communication by obtaining a measured value Dx according to the distance between these two parties through communication. Be prepared. The unauthorized communication prevention system 19 includes a first communication device 20 provided on one of the vehicle 1 and the terminal 2, and a second communication device 21 provided on the other. In the case of this example, for example, the first communication device 20 is the terminal 2, and the second communication device 21 is the vehicle 1 (verification ECU 7), for example. The communication between the first communication device 20 and the second communication device 21 is preferably, for example, Bluetooth (Bluetooth: registered trademark).

The fraudulent communication prevention system 19 transmits and receives radio wave Si between a first communication device 20 and a second communication device 21 wirelessly connected over a plurality of channels, and transmits and receives propagation characteristics (for example, amplitude and phase) in each of these channels. Ask. Then, the unauthorized communication prevention system 19 synthesizes the obtained propagation characteristics of the plurality of channels and performs an inverse Fourier transform on the propagation characteristics obtained by the synthesis to equivalently calculate the propagation time of the impulse, that is, the measured value Dx. ..

The fraudulent communication prevention system 19 transmits radio wave Si from the first communication device 20 to the second communication device 21 to measure the propagation characteristics, and also transmits radio wave Si from the second communication device 21 to the first communication device 20. And measure the propagation characteristics. As described above, in the unauthorized communication prevention system 19 of this example, the radio wave Si is transmitted and received between the first communication device 20 and the second communication device 21, and both the first communication device 20 and the second communication device 21 transmit and receive radio waves Si. Measure the propagation characteristics.

As shown in FIG. 3, the fraudulent communication prevention system 19 includes a determination unit 22 for determining whether the communication (smart communication) is correct or not based on the measured value Dx obtained from the radio wave communication between the two parties. When communication is established between the first communication device 20 and the second communication device 21 (exchange of wake signal and ack signal), the determination unit 22 of this example measures a measured value Dx according to the distance between the two. Is obtained, and based on this measured value Dx, it is determined whether the communication between the two parties is regular communication or unauthorized communication. The determination unit 22 is a radio wave transmission unit 23 that transmits radio wave Si for distance measurement, a radio wave reception unit 24 that receives radio wave Si for distance measurement, and a processing execution unit that executes a series of processing from the transmitted / received radio wave Si. 25 and.

The radio wave transmission unit 23 includes a waveform generation unit 28, a modulation unit 29, a DA converter 30, a mixer 31, an oscillator 32, and a transmission antenna 33. The waveform generation unit 28 generates a periodic signal Sk composed of a binarized code as a radio wave Si for distance measurement, and outputs this to the modulation unit 29. The periodic signal Sk is a signal in which the binarization codes "0" and "1" are switched every cycle. The modulation unit 29 modulates the input signal with GFSK (Gaussian Frequency Shift Keying). The periodic signal Sk is modulated by the modulation unit 29, D / A converted by the DA converter 30, and then the baseband signal Sb is superimposed on the carrier wave of the oscillator 32 by the mixer 31 and transmitted from the transmission antenna 33. ..

The radio wave receiving unit 24 includes a receiving antenna 34, a mixer 35, an oscillator 36, an AD converter 37, and a Fourier transform unit 38. When the radio wave receiving unit 24 receives the radio wave Si of the periodic signal Sk transmitted from the radio wave transmitting unit 23 by the receiving antenna 34, the received radio wave is converted into the baseband signal Sb by the mixer 35, and this is converted into the baseband signal Sb by the AD converter 37. Convert to D. The Fourier transform unit 38 performs a Fourier transform (FFT transform) on the signal after the A / D transform to extract the propagation characteristics of the radio wave Si. The propagation characteristic consists of a group of data on the amplitude and phase of the radio wave Si. The propagation characteristic is preferably a DC component propagation characteristic which is a characteristic value when the frequency is "0" in the frequency spectrum after the Fourier transform (after the FFT transform).

The unauthorized communication prevention system 19 measures the propagation characteristics during communication on all the channels to be communicated. When the communication is Bluetooth, since there are a plurality of channels (for example, 40 channels), the measurement of the propagation characteristics is performed in all the channels (CH1, CH2, ..., CHn). As described above, in the case of this example, the radio wave Si is transmitted on a plurality of frequencies by transmitting the radio wave Si on a plurality of channels.

The processing execution unit 25 includes a multiplication unit 41, a composition unit 42, an inverse Fourier transform unit 43, and a determination processing unit 44. The multiplication unit 41, the composition unit 42, the inverse Fourier transform unit 43, and the determination processing unit 44 may be provided in either the first communication device 20 or the second communication device 21.

The multiplication unit 41 has a propagation characteristic measured by transmitting radio waves from the first communication device 20 to the second communication device 21 and a propagation characteristic measured by transmitting radio waves from the second communication device 21 to the first communication device 20. To multiply. As described above, the multiplying unit 41 of this example transmits the FFT result obtained by transmitting radio waves from the first communication device 20 to the second communication device 21 and the radio wave transmission from the second communication device 21 to the first communication device 20. Multiply by the obtained FFT result.

The synthesis unit 42 synthesizes the propagation characteristics of the extracted plurality of channels. The synthesis unit 42 of this example obtains frequency data H (f) composed of a vector in which the propagation characteristics of each channel are arranged.
The inverse Fourier transform unit 43 performs an inverse Fourier transform on the propagation characteristics after synthesis, and calculates a measured value Dx according to the distance between the first communication device 20 and the second communication device 21. The inverse Fourier transform unit 43 of this example performs an inverse Fourier transform on the frequency data H (f) obtained by the synthesis unit 42, and obtains the time data y (t) as the measured value Dx from this calculation.

The determination processing unit 44 determines the validity of the measured value Dx (time data y (t)) calculated by the inverse Fourier transform. The determination processing unit 44 of this example compares the measured value Dx with the predetermined specified value Dk, and when the measured value Dx is less than the specified value Dk, the communication of the first communication device 20 and the second communication device 21 is regular communication. Is determined. On the other hand, when the measured value Dx is equal to or greater than the specified value Dk, the determination processing unit 44 determines that the communication between the first communication device 20 and the second communication device 21 is illegal communication. When the determination processing unit 44 determines that the communication is an unauthorized communication, even if the ID verification and the challenge response authentication are established in the smart verification, the determination processing unit 44 does not shift the smart verification to the establishment. Further, when the determination processing unit 44 determines that the communication is an illegal communication, if the smart communication is being executed, the smart communication is terminated in the middle of the process, so that the smart collation is not established.

When the communication between the first communication device 20 and the second communication device 21 is determined to be unauthorized communication, the unauthorized communication prevention system 19 re-executes (retries) the process of determining whether the communication is normal / illegal. Therefore, when the communication between the first communication device 20 and the second communication device 21 is illegal communication, a series of processes of transmitting and receiving radio waves Si, measuring the propagation characteristics, and obtaining the measured value Dx are performed again.

The fraudulent communication prevention system 19 includes a confirmation unit 45 for confirming whether or not a determination result determined to be fraudulent communication occurs a plurality of times in the determination of normality / fraudulent communication. The confirmation unit 45 of this example confirms whether or not the determination results determined to be unauthorized communication are continuous.

The fraudulent communication prevention system 19 includes a control unit 46 that controls communication between the first communication device 20 and the second communication device 21 based on the confirmation result of the confirmation unit 45. When a plurality of determination results determined to be unauthorized communication occur, the control unit 46 of this example performs wireless authentication of the first communication device 20 and the second communication device 21 as a countermeasure against the unauthorized communication. Control communication. When the determination results determined to be unauthorized communication are continuous, the control unit 46 determines the determination result that the communication is unauthorized communication and takes measures against the unauthorized communication. As a countermeasure, for example, there is a process of strictly (decreasing the value) the specified value Dk used for determining whether or not the communication is unauthorized, or forcibly stopping the function (smart function) of the smart collation system.

Next, the operation and effect of the unauthorized communication prevention system 19 of the present embodiment will be described with reference to FIGS. 4 to 6.
As shown in FIG. 4, in step 101, the first communication device 20 transmits the radio wave Si to the second communication device 21 and causes the second communication device 21 to measure the propagation characteristics. In the case of this example, the waveform generation unit 28 first generates a periodic signal Sk in which "0" and "1" are periodically repeated, and outputs this to the modulation unit 29. The modulation unit 29 GFSK-modulates the periodic signal Sk of the repeated signals of "0" and "1", and outputs this to the DA converter 30. The DA converter 30 performs D / A conversion of the modulated signal. The baseband signal Sb D / A-converted by the DA converter 30 is placed on a carrier wave by the mixer 31 and transmitted as radio wave Si from the transmission antenna 33. When the radio wave Si is transmitted by a plurality of channels, the radio wave Si of each channel is transmitted on the corresponding carrier.

The second communication device 21 receives the radio wave Si transmitted from the first communication device 20 by the receiving antenna 34. The signal received by the receiving antenna 34 is converted into a baseband signal Sb through the mixer 35. The baseband signal Sb is A / D converted by the AD converter 37 and output to the Fourier transform unit 38. The Fourier transform unit 38 Fourier transforms the signal after the A / D conversion, and measures the propagation characteristics (amplitude and phase of the frequency spectrum) of the baseband signal Sb. The propagation characteristic is preferably, for example, the propagation characteristic of the center frequency of the received radio wave received by the radio wave receiving unit 24.

In step 102, the second communication device 21 transmits the radio wave Si to the first communication device 20, and causes the first communication device 20 to measure the propagation characteristics (amplitude and phase). That is, the radio wave Si is transmitted from the second communication device 21 to the first communication device 20, and the propagation characteristics (amplitude and phase) are also measured in the first communication device 20. Since the measurement of the propagation characteristic is the same as the case where the radio wave is transmitted from the first communication device 20 to the second communication device 21, the description thereof will be omitted.

When the propagation characteristics are measured in the round trip between the first communication device 20 and the second communication device 21, the multiplication unit 41 transmits radio waves from the first communication device 20 to the second communication device 21 and measures the propagation characteristics. (FFT result) is multiplied by the propagation characteristics (FFT result) measured by transmitting radio waves from the second communication device 21 to the first communication device 20. As a result, even if a clock error or an initial phase error of the PLL occurs in each device of the unauthorized communication prevention system 19, these errors appear as phase errors of opposite signs on the transmitting side and the receiving side. The resulting multiplication cancels these errors.

In step 103, the first communication device 20 and the second communication device 21 sequentially measure the propagation characteristics in each channel of communication. When the communication is Bluetooth, since there are a plurality of channels (for example, 40 channels), the propagation characteristics of the communication (round trip) are measured in all of the channels. Therefore, for example, when radio waves of CH2 to CHn are transmitted and received, the propagation characteristics H (f2) to H (fn) of the center frequencies f2 to fn of each channel can be obtained. The reason for measuring the propagation characteristics of multiple frequencies is that an impulse cannot be created with the propagation characteristics of one frequency.

In step 104, the synthesis unit 42 synthesizes the round-trip propagation characteristics of all channels. In the case of this example, the synthesis unit 42 creates a vector in which the propagation characteristics of each channel are arranged. In this example, [H (f1), H (f2), ..., H (fn)] is obtained as a vector in which the propagation characteristics of each channel are arranged, that is, the frequency data H (f).

In step 105, the inverse Fourier transform unit 43 performs an inverse Fourier transform on the propagation characteristics (frequency data H (f)) after synthesis. In the case of this example, a vector (frequency data H (f)) is used as input data, which is subjected to inverse Fourier transform, and the calculation result is acquired. The operation result of the inverse Fourier transform can be acquired as time data y (t). The time data y (t) is represented by [y (t1), y (t2), ..., Y (tn)]. In addition, t1 to tn are time data corresponding to each propagation characteristic H (f1) to H (fn). The determination processing unit 44 uses the measured value Dx obtained from the time data y (t) to execute a normal / invalid determination of communication from the measured value Dx.

As shown in FIG. 5, it is assumed that an unauthorized communication is attempted in which an LF radio wave is relayed between the vehicle 1 and the terminal 2 by a repeater and authentication (smart verification) is illegally established between the two parties. In this fraudulent act, in order to make the terminal 2 appear to be located near the vehicle 1, the phase information of the radio wave Si for distance measurement is randomly altered and relayed, and the correctness judgment of the communication is illegally established. And. However, since this fraudulent activity is determined with a low probability, in fact, in the determination of the validity of the measured value Dx, if the determination result that the measured value Dx becomes the specified value Dk or more continues many times. is assumed.

In the case of unauthorized communication using a repeater, the confirmation unit 45 should confirm that the measured value Dx is equal to or higher than the specified value Dk multiple times. In this case, the vehicle 1 and the terminal 2 in the established state are tried. Take measures against unauthorized communication. Therefore, when the confirmation unit 45 confirms that the measured value Dx is equal to or higher than the specified value Dk, the confirmation unit 45 determines the determination result that the communication is illegal communication and notifies that the countermeasure against the illegal communication is to be taken. The request) is output to the control unit 46.

When the control unit 46 inputs a response implementation request from the confirmation unit 45, the control unit 46 executes countermeasures against unauthorized communication through radio wave relay. As a countermeasure against unauthorized communication through radio wave relay, the control unit 46 of this example strictly tightens (decreases) the specified value Dk used in the determination of normality / illegality of communication, or functions the smart collation system (smart function). Forcibly stop. Therefore, it is difficult for the correctness determination of the communication to be illegally transferred to the establishment, and it is possible to prevent the establishment of the unauthorized communication by a third party.

The fraudulent communication prevention system 19 may include a function (return function) of returning the smart collation system from the stop when the smart collation system (smart function) is forcibly stopped. In this case, it is preferable that the return of the smart collation system is, for example, a process that imposes an operation of the terminal 2 by the user. The operation of the terminal 2 by the user is, for example, through the operation of various buttons provided on the terminal 2 (remote operation by wireless communication) or the immobilizer communication in which the terminal 2 is held over the short-range wireless antenna of the vehicle 1 and authenticated by RFID. There are operations and so on.

By the way, in the case of this example, when the determination result that the communication is illegal communication is detected multiple times (continuous detection), the communication when the first communication device 20 and the second communication device 21 perform wireless authentication is controlled. Then, take appropriate measures against unauthorized communication. In this way, when the determination result that the communication is unauthorized communication is detected multiple times (continuous detection), if the determination result of the presence of unauthorized communication is confirmed and the countermeasure is taken, the unauthorized communication is accurately determined. It will be advantageous to do. Therefore, it is possible to ensure the accuracy of determining that the communication is unauthorized communication.

The confirmation unit 45 confirms whether or not the determination results determined to be unauthorized communication are continuous. The control unit 46 executes processing for unauthorized communication when the determination results determined to be unauthorized communication are continuous. Therefore, it is possible to take measures against unauthorized communication in a situation where there is a high possibility that the communication will be illegally transferred to the establishment by a third party.

When the confirmation unit 45 detects a determination result in which the measured value Dx has a significantly unreasonable value a plurality of times, the confirmation unit 45 may cause the control unit 46 to take measures against the unauthorized communication. The significantly unreasonable value is preferably, for example, a value sufficiently larger than the specified value Dk (for example, 50 m, 100 m, etc.). In this case, although the measured value Dx is equal to or greater than the specified value Dk, when a determination result of a significantly unreasonable value or less is obtained, the determination is retried without determining the communication as unreasonable, and the measured value Dx is a significantly unreasonable value. When is detected multiple times, the communication is recognized as invalid and the countermeasure is taken. Therefore, it is possible to take measures against unauthorized communication in a situation where there is a high possibility that unauthorized communication by a third party is being attempted.

Further, as shown in FIG. 6, the confirmation unit 45 uses the measured value Dx and an index value different from the measured value Dx, and the determination result is determined to be unauthorized communication from the combined determination of these values. You may check whether or not multiple occurrences occur. As an example of this, for example, when another index value is "integration of the difference (Dk-Dx) between the measured value Dx and the specified value Dk", the difference when the measured value Dx becomes the specified value Dk or more is not so large. If it is not significant, the determination result of unauthorized communication is shifted to finalization on condition that the number of times of determination of unauthorized communication occurs frequently (example in the upper part of FIG. 6). Further, if the difference when the measured value Dx becomes the specified value Dk or more is large, the judgment result of the fraudulent communication is shifted to the final decision even if the number of times the fraudulent communication is determined is small (example in the lower part of FIG. 6). ). Therefore, it is advantageous to accurately determine whether the communication is regular communication or illegal communication.

The distance measuring method of the unauthorized communication prevention system 19 is a distance measuring method using a signal of Bluetooth communication. In the case of this method, the determination unit 22 causes one of the first communication device 20 and the second communication device 21 to transmit a plurality of radio wave Si by changing the channel to the other, and measures the measured value based on the phase difference of the radio wave Si of each channel. Dx is obtained, and from this measured value Dx, it is determined whether the communication between the two parties is regular communication or unauthorized communication. By the way, in the case of this distance measuring method, it is necessary to falsify the phase information of the radio wave Si in order to establish communication illegally, but it can be said that the probability that unauthorized communication is established is low in random falsification. .. Therefore, when an unauthorized communication is attempted, there is a high possibility that the unauthorized communication is repeated many times, and the number of times that the normal / illegal determination result becomes the unauthorized communication increases. It can be said that this is highly effective in detecting unauthorized communication without omission when confirming the correctness of communication using the determination logic of this example.

In addition, this embodiment can be changed and carried out as follows. The present embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
-As shown in FIG. 7, as a method for determining unauthorized communication, for example, radio waves are transmitted and received between the first communication device 20 and the second communication device 21, and the time (time stamp or the like) required for the radio wave transmission / reception is measured. , It may be a method of determining the legitimacy / invalidity of communication. In this case, it is preferable to use, for example, a UWB (Ultra Wide Band) band radio wave as the radio wave to be transmitted and received.

-When the measured value Dx becomes the specified value Dk or more, the series of measurement-judgment processing is retried without confirming the normal / invalid judgment result of the communication, and the situation of unauthorized communication occurs multiple times. In addition, any aspect may be used as long as the determination result of unauthorized communication is determined.

-The communication when performing wireless authentication may be either distance measurement communication or smart collation communication.
The measured value Dx is not limited to the distance measurement value which is the distance between the first communication device 20 and the second communication device 21, and is not limited to other parameters such as the received signal strength (RSSI) when the radio wave Si is received. May be changed to.

-Multiple detection of unauthorized communication is not limited to continuous detection, and may be discontinuous, for example.
-The measures taken when unauthorized communication is detected are not limited to the examples described in the embodiment, and various methods can be applied as long as it is possible to prevent the establishment of communication between the two parties.

-The other index value is not limited to the difference when the measured value Dx becomes the specified value Dk or more and the number of times the determination is NG, and various other parameters can be appropriately adopted.
-Wireless authentication is not limited to smart verification, and may be any communication that can confirm the correctness of the terminal 2.

-The correctness determination of communication is not limited to being performed only on a plurality of channels, and may be performed using only one channel. In this case, for example, by switching the center frequency of the baseband signal in one channel, the radio wave Si is transmitted a plurality of times, and the correctness / rejection of the communication is determined using each radio wave Si.

-The propagation characteristics are not limited to both amplitude and phase, and may be only one. Further, parameters other than these may be used for the propagation characteristics.
-The propagation characteristic may be a characteristic value other than the DC component.

-The correctness judgment of communication is not limited to being carried out after distance measurement, and the timing of being carried out, such as before or during distance measurement, is not particularly limited.
-The periodic signal Sk is not limited to the periodic signals of "0" and "1", and may be, for example, only "0" or only "1". Further, the combination of "0" and "1" can be appropriately changed as long as the binarization code is periodically repeated, such as a signal in which the data group of "0", "0", and "1" is repeated. ..

The first communication device 20 may be a high-performance mobile phone having an electronic key function.
-Various frequencies can be adopted as the frequency of the radio wave.
-The digital code is not limited to the binarized code, and may be changed to another code assuming the case of using modulation such as QPSK (Quadrature Phase Shift Keying).

-The modulation unit 29 is not limited to GFSK, and may be changed to other members such as mere FSK.
The calculation of the measured value Dx is not limited to the calculation using the Fourier transform (inverse Fourier transform), and other calculation methods may be adopted.

The first communication device 20 is not limited to the terminal 2 (electronic key), and the second communication device 21 is not limited to the vehicle 1. For example, the first communication device 20 may be a wireless communication type personal computer, and the second communication device 21 may be a wireless LAN router.

-The fraudulent communication prevention system 19 is not limited to a system that transmits and receives radio waves to perform distance measurement. For example, a unidirectional method may be used in which radio waves are transmitted from one of the first communication device 20 and the second communication device 21 to only the other to measure the distance. Further, the first communication device 20 and the second communication device 21 transmit and receive radio waves, and once again, the radio waves are transmitted from one of the first communication device 20 and the second communication device 21 to the other, and then the propagation characteristics are obtained. The distance between the two may be measured.

-The communication method is not limited to Bluetooth and UWB, and may be other communication such as wireless LAN.
-The fraudulent communication prevention system 19 is not limited to being used for an electronic key system that wirelessly authenticates an electronic key for a vehicle, and may be applied to various systems and devices.

1 ... vehicle, 2 ... terminal, 20 ... first communication device, 21 ... second communication device, 22 ... judgment unit, 45 ... confirmation unit, 46 ... control unit, Dx ... measured value.

Claims (8)

When communication is established between the first communication device and the second communication device, a measured value according to the distance between the two parties is obtained, and based on the measured value, the communication between the two parties is regular communication or illegal. A judgment unit that determines which of the communications is used, and
A confirmation unit that confirms whether or not the determination result determined to be unauthorized communication occurs multiple times,
A control unit that controls communication when the first communication device and the second communication device perform wireless authentication as a countermeasure against the unauthorized communication when the determination result determined to be unauthorized communication occurs a plurality of times. And with
The confirmation unit is an unauthorized communication prevention system that causes the control unit to take measures against unauthorized communication when a determination result in which the measured value is extremely unreasonable is detected a plurality of times . When communication is established between the first communication device and the second communication device, a measured value according to the distance between the two parties is obtained, and based on the measured value, the communication between the two parties is regular communication or illegal. A judgment unit that determines which of the communications is used, and
A confirmation unit that confirms whether or not the determination result determined to be unauthorized communication occurs multiple times,
A control unit that controls communication when the first communication device and the second communication device perform wireless authentication as a countermeasure against the unauthorized communication when the determination result determined to be unauthorized communication occurs a plurality of times. And with
The determination unit causes one of the first communication device and the second communication device to transmit a plurality of radio waves by changing channels to the other, obtains the measured value based on the phase difference of the radio waves of each channel, and obtains the measured value. An unauthorized communication prevention system that determines whether communication between two parties is regular communication or unauthorized communication from measured values . The confirmation unit confirms whether or not the determination results determined to be unauthorized communication are continuous.
The unauthorized communication prevention system according to claim 1 or 2, wherein the control unit executes measures against the unauthorized communication when the determination results determined to be unauthorized communication are continuous. The confirmation unit uses the measured value and an index value different from the measured value, and confirms whether or not the determination result determined to be unauthorized communication occurs a plurality of times from the combined determination of these values. The unauthorized communication prevention system according to any one of claims 1 to 3. When communication is established between the first communication device and the second communication device, the measured value according to the distance between the two is obtained, and the two parties are based on the comparison between the measured value and the predetermined specified value . A determination unit that determines whether the communication between the two is legitimate communication or unauthorized communication,
A confirmation unit that confirms whether or not the number of times that it is determined to be unauthorized communication occurs a predetermined number of times ,
A control unit that controls communication when the first communication device and the second communication device perform wireless authentication as a countermeasure against the unauthorized communication when the determination result determined to be unauthorized communication occurs a predetermined number of times. And with
The confirmation unit is an unauthorized communication prevention system that changes the predetermined number of times according to the difference between the measured value and the specified value . When communication is established between the first communication device and the second communication device, a measured value according to the distance between the two parties is obtained, and based on the measured value, the communication between the two parties is regular communication or illegal. Steps to determine which is communication and
A step of confirming whether or not a determination result determined to be unauthorized communication occurs multiple times because the measured value becomes a significantly unreasonable value, and a step of confirming.
When the determination result determined to be unauthorized communication occurs a plurality of times, as a countermeasure against the unauthorized communication, a step of controlling communication when the first communication device and the second communication device perform wireless authentication. Unauthorized communication prevention method equipped with. When communication is established between the first communication device and the second communication device, a measured value according to the distance between the two parties is obtained, and based on the measured value, the communication between the two parties is regular communication or illegal. A judgment step for determining which of the communications is used, and
A confirmation step to confirm whether the determination result determined to be unauthorized communication occurs multiple times, and
A control step for controlling communication when the first communication device and the second communication device perform wireless authentication as a countermeasure against the unauthorized communication when the determination result determined to be unauthorized communication occurs a plurality of times. And with
In the determination step, a plurality of radio waves are transmitted from one of the first communication device and the second communication device by changing the channel to the other, and the measured value is obtained based on the phase difference of the radio waves of each channel. An unauthorized communication prevention method for determining whether communication between two parties is regular communication or unauthorized communication from measured values. When communication is established between the first communication device and the second communication device, the measured value according to the distance between the two is obtained, and the two parties are based on the comparison between the measured value and the predetermined specified value. A determination step for determining whether the communication between the two is legitimate communication or unauthorized communication, and
A confirmation step to confirm whether or not the number of times that it is determined to be unauthorized communication occurs a predetermined number of times, and
A control step for controlling communication when the first communication device and the second communication device perform wireless authentication as a countermeasure against the unauthorized communication when the determination result determined to be unauthorized communication occurs a predetermined number of times. And with
The confirmation step is a method for preventing unauthorized communication in which the predetermined number of times is changed according to the difference between the measured value and the specified value.

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