JP2018040133A - Authentication system and mobile unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent more reliably fraudulent authentication using wireless communication.SOLUTION: A mobile unit 2 includes: a second LF reception antenna 24 for receiving a signal of a frequency number f3 generated by tertiary intermodulation distortion between frequency numbers f2 and f1, when request signals of the frequency number f1 and the frequency number f2 are sent simultaneously; a second reception intensity identification part 25 for identifying signal intensity of the signal received by the second LF reception antenna 24; and a control part 29 for processing fraudulent authentication using wireless communication, on the basis of the reception signal intensity identified by the second reception intensity identification part 25.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an authentication system that performs authentication using wireless communication, and a portable device included in the authentication system.

  2. Description of the Related Art Conventionally, there is known an authentication system that enables vehicle control such as locking / unlocking of a vehicle door, engine starting, and the like based on the establishment of code verification by wireless communication between an in-vehicle device and a portable device such as an electronic key. . Since the distance range in which wireless communication is possible is limited to a short distance around the vehicle, authentication using wireless communication is normally possible only when the portable device is located in the vicinity of the vehicle.

  However, in such an authentication system, there is a concern that a third party with malicious intent can establish authentication by indirectly realizing communication between the portable device and the vehicle-mounted device using a repeater. . In the relay attack, although it is not intended by a legitimate user, authentication is established and vehicle control such as unlocking the vehicle door and starting the engine becomes possible.

  On the other hand, for example, Patent Document 1 discloses a technique for preventing a relay attack by utilizing that a repeater amplifies a signal to be relayed and transmits the signal with a constant signal strength. In the technique disclosed in Patent Document 1, the signal strength of a request signal transmitted from an in-vehicle device is changed in a fixed pattern, and a response is made only when a change in the strength is detected by a portable device, so that a relay attack is performed. Trying to prevent.

JP 2010-185186 A

  However, the technique disclosed in Patent Document 1 has a problem that a relay attack cannot be prevented when the repeater restores the change in signal strength of the request signal in a fixed pattern.

  The present invention has been made in view of the above-described conventional problems, and an object thereof is to provide an authentication system and a portable device that can more reliably prevent unauthorized authentication using wireless communication. It is in.

  The above object is achieved by a combination of the features described in the independent claims, and the subclaims define further advantageous embodiments of the invention. Reference numerals in parentheses described in the claims indicate a correspondence relationship with specific means described in the embodiments described later as one aspect, and do not limit the technical scope of the present invention. .

  In order to achieve the above object, an authentication system of the present invention includes a master device (10) including a transmission processing unit (102) for transmitting a request signal for requesting code verification by wireless communication at a predetermined frequency f1, and a user. And a portable device (2, 2a, 2b, 2c, 2d) provided with a reply unit (28) that transmits a response signal including an identification code for identifying the own device with respect to the request signal. The master device includes an authentication unit (104) that performs authentication by code verification using an identification code included in a response signal transmitted from the reply unit, and the transmission processing unit transmits the request signal to the frequency Simultaneously with the transmission at f1, a predetermined signal is transmitted by wireless communication at a frequency f2 different from the frequency f1, and the portable device receives the request signal transmitted at the frequency f1. Received by the request receiving antenna (21), the modulated wave receiving antenna (24) for receiving the signal of the frequency f3 generated by the third-order intermodulation distortion of the frequency f1 and the frequency f2, and the modulated wave receiving antenna A modulation wave signal intensity specifying unit (25) that specifies the signal intensity of the signal, and a fraud countermeasure unit (25) that performs processing for unauthorized authentication using wireless communication based on the signal intensity specified by the modulation wave signal intensity specifying unit. 29, 29b, 29c, 29d).

  In order to achieve the above object, the portable device of the present invention includes a master device (10) that transmits a request signal for requesting code verification by wireless communication at a predetermined frequency f1, and a portable device (2) carried by the user. , 2a, 2b, 2c, 2d), a request for receiving a request signal transmitted at the frequency f1 used in the vehicle authentication system (3) that performs authentication by code verification using wireless communication. Due to the third-order intermodulation distortion of the frequency f2 and the frequency f1, which are different from the frequency f1, which is the frequency of the signal transmitted at the same time as the request signal is transmitted at the frequency f1 by the receiving antenna (21) and the master device. Modulated wave receiving antenna (24) for receiving the signal of the generated frequency f3, and modulated wave signal strength specifying for specifying the signal strength of the signal received by the modulated wave receiving antenna Includes a (25), based on the signal strength identified in modulated signal strength specific unit, illegal coping unit that performs processing for unauthorized authentication using wireless communication (29,29b, 29c, 29d) and a.

  According to these, wireless communication based on the signal strength of the signal of the frequency f3 generated by the third-order intermodulation distortion of the frequency f1 and the frequency f2 of the signal simultaneously transmitted from the master device received by the modulated wave receiving antenna. Processing for unauthorized authentication using. The signal strength of the signal of the frequency f3 generated by the third-order intermodulation distortion has a waveform reproducibility due to signal amplification performed by the repeater when relaying wireless communication from the master device to the portable device using the repeater. There is a characteristic that changes. Therefore, the signal strength of the signal of frequency f3 changes depending on the presence or absence of unauthorized authentication using wireless communication. Therefore, unauthorized authentication using wireless communication can be more reliably prevented by performing processing for unauthorized authentication using wireless communication based on the signal strength specified by the modulated wave signal strength specifying unit. It becomes.

It is a figure which shows an example of a schematic structure of the authentication system. 2 is a diagram illustrating an example of a schematic configuration of a vehicle-side unit 1. FIG. It is a flowchart which shows an example of the flow of the smart related process at the time of boarding in collation ECU10. 2 is a diagram illustrating an example of a schematic configuration of a portable device 2. FIG. It is a figure for demonstrating the difference which deducted the transmission wave increase part from the intermodulation wave increase part at the time of receiving a signal directly from the vehicle side unit 1, and this difference at the time of using a repeater. 10 is a flowchart illustrating an example of a flow of mobile-side smart-related processing in the mobile device 2. It is a figure which shows an example of a schematic structure of the portable device 2a. It is a figure which shows an example of a schematic structure of the portable device 2b. It is a figure for demonstrating about the received signal strength of the signal of the intermodulation wave when receiving a signal directly from the vehicle side unit 1, and this received signal strength when passing through a repeater. It is a figure which shows an example of a schematic structure of the portable device 2c. For explaining the difference obtained by subtracting the received signal strength of the frequency f1 from the received signal strength of the intermodulation wave when the signal is directly received from the vehicle side unit 1 and this difference when passing through the repeater FIG. It is a figure which shows an example of a schematic structure of the portable device 2d.

  A plurality of embodiments for disclosure will be described with reference to the drawings. For convenience of explanation, among the embodiments, parts having the same functions as those shown in the drawings used in the explanation so far may be given the same reference numerals and explanation thereof may be omitted. is there. For the parts denoted by the same reference numerals, the description in other embodiments can be referred to.

(Embodiment 1)
<Schematic configuration of authentication system 3>
As shown in FIG. 1, the authentication system 3 includes a vehicle-side unit 1 used in a vehicle and a portable device 2 as an electronic key carried by the user. The authentication system 3 has a so-called smart function. The smart function performs code verification by short-range wireless communication between the vehicle-side unit 1 and the portable device 2, and permits the locking / unlocking of the vehicle door and starting of the driving source based on the code verification being established. Refers to the function to do.

<Schematic configuration of vehicle-side unit 1>
First, the schematic configuration of the vehicle-side unit 1 will be described with reference to FIG. As shown in FIG. 2, the vehicle-side unit 1 includes a verification ECU 10, a first LF transmission antenna 11, a first LF transmission unit 12, a second LF transmission antenna 13, a second LF transmission unit 14, a UHF reception antenna 15, a UHF reception unit 16, and A body ECU 17 is provided. The verification ECU 10 corresponds to the master device and the in-vehicle device in the claims.

  The first LF transmission antenna 11 is an antenna for transmitting a signal using radio waves in the LF band. The LF band is a frequency band of 30 kHz to 300 kHz, for example. A range in which signals can be transmitted from the first LF transmitting antenna 11 using radio waves in the LF band corresponds to a short-range wireless communication area where short-range wireless communication is possible. In the present embodiment, the first LF transmission antenna 11 will be described below assuming that the first LF transmission antenna 11 transmits a radio wave having a frequency f1 in the LF band.

  The first LF transmission unit 12 requests the portable device 2 to transmit a WAKE signal for releasing the sleep state of the portable device 2 and the identification code of the portable device 2 used for code verification via the first LF transmission antenna 11. Send a request signal. The first LF transmission unit 12 outputs a WAKE signal and a request signal from the first LF transmission antenna 11 by using a radio wave having a frequency f1 by outputting a signal obtained by modulating the WAKE signal and the request signal to the first LF transmission antenna 11.

  The second LF transmission antenna 13 is also an antenna for transmitting a signal using radio waves in the LF band. The second LF transmission antenna 13 is provided in a pair with the first LF transmission antenna 11 and transmits a radio wave having a frequency f2 different from the frequency f1 of the first LF transmission antenna 11. The transmission outputs of the second LF transmission antenna 13 and the first LF transmission antenna 11 are approximately the same, and the short-range wireless communication area is also approximately the same. The frequency f1 and the frequency f2 need only be different from each other as long as they are values that fall within the LF band as in the present embodiment. For example, when using a frequency band of 100 MHz or more, the frequencies f1 and f2 It is preferable to make the values close to each other so that the difference between them is several tens of MHz or less.

  In FIG. 2, for convenience, only one first LF transmission antenna 11 and one second LF transmission antenna 13 are shown, but a set of the first LF transmission antenna 11 and the second LF transmission antenna 13 is provided near the side door or in the trunk. It is good also as a structure by which each is arrange | positioned.

  The second LF transmission unit 14 transmits a signal via the second LF transmission antenna 13. The second LF transmission unit 14 may be configured to transmit a WAKE signal or a request signal. However, in order to suppress the possibility of inconvenience and waste due to overlapping transmission with the first LF transmission unit 12, the second LF transmission may be performed. A configuration in which the WAKE signal and the request signal are not transmitted from the unit 14 is preferable. The second LF transmission unit 14 outputs a signal obtained by modulating a predetermined signal (hereinafter referred to as an intermodulation signal) other than the WAKE signal and the request signal to the second LF transmission antenna 13, so that the second LF transmission antenna 13 receives the frequency f2. The intermodulation signal is transmitted using the radio wave.

  The UHF receiving antenna 15 is an antenna for receiving a signal transmitted with a radio wave in the UHF band. The UHF band is a frequency band of 300 MHz to 3 GHz, for example. The UHF receiving unit 16 demodulates the signal received by the UHF receiving antenna 15 and outputs the demodulated signal to the verification ECU 10. The response signal is a response signal to the WAKE signal or a response signal to the request signal.

  The body ECU 17 locks and unlocks each vehicle door by outputting a drive signal for controlling locking and unlocking of each vehicle door to a door lock motor provided in each vehicle door. The body ECU 17 is connected to a touch sensor provided on the outer door handle of each vehicle door, and detects that the outer door handle of each vehicle door has been touched by the user. In addition, a courtesy switch for each vehicle door is connected to the body ECU 17 to detect opening and closing of each vehicle door.

  The verification ECU 10 includes a processor, a volatile memory, a nonvolatile memory, an I / O, and a bus for connecting them, and executes various processes by executing a control program stored in the nonvolatile memory. The verification ECU 10 executes processing related to the smart function. A schematic configuration of the verification ECU 10 will be described below.

<Detailed Configuration of Verification ECU 10>
As shown in FIG. 2, the verification ECU 10 includes a registration unit 101, a transmission processing unit 102, a reception processing unit 103, a code verification unit 104, and a locking / unlocking permission unit 105. Note that some or all of the functions executed by the verification ECU 10 may be configured in hardware by one or a plurality of ICs.

  The registration unit 101 is, for example, an electrically rewritable nonvolatile memory, and the portable device identification code of the authorized user's portable device 2 is a portable device identification code that is a code for identifying the portable device 2. It is registered.

  The transmission processing unit 102 sends the WAKE signal to the first LF transmission unit 12 and causes the first LF transmission antenna 11 to transmit the WAKE signal using radio waves having the frequency f1. When the first LF transmission antenna 11 is arranged near the side door or in the trunk, the WAKE signal may be transmitted in order from each first LF transmission antenna 11.

  In addition, the transmission processing unit 102 transmits a request signal to the first LF transmission unit 12 and also transmits an intermodulation signal to the second LF transmission unit 14 to transmit signals from the first LF transmission antenna 11 and the second LF transmission antenna 13 simultaneously. . In this case, the first LF transmission antenna 11 transmits a request signal (hereinafter referred to as a request signal) including a vehicle identification code, which is a code for identifying the vehicle, by radio waves having a frequency f1, and the second LF transmission antenna 13 Causes the intermodulation signal to be transmitted by radio waves of frequency f2. The vehicle identification code may be the device ID of the verification ECU 10 mounted on the vehicle or the vehicle ID of the vehicle. What is necessary is just to set it as the structure which reads and uses what was stored in the non-volatile memory of collation ECU10 for vehicle identification code.

  In addition, when it is set as the structure by which the 1st LF transmission antenna 11 and the 2nd LF transmission antenna 13 are each arrange | positioned in the side door vicinity, a trunk, etc., it should just be as follows. Specifically, when the WAKE signal is transmitted, the reception processing unit 103 can receive the WAKE response signal from the first LF transmission antenna 11 and the second LF transmission antenna 13 paired with the first LF transmission antenna 11. What is necessary is just to set it as the structure which transmits a signal simultaneously.

  The reception processing unit 103 receives a WAKE response signal transmitted from the portable device 2 in the UHF band in response to the WAKE signal via the UHF reception unit 16. In addition, the reception processing unit 103 receives a response signal (hereinafter referred to as a request response signal) transmitted from the portable device 2 in the UHF band in response to the request signal via the UHF receiving unit 16.

  The code verification unit 104 performs authentication by code verification to determine whether the mobile device 2 that is the transmission source of the request response signal received by the reception processing unit 103 is the mobile device 2 of the authorized user. The code verification unit 104 corresponds to an authentication unit in the claims. The code verification is performed between the portable device identification code included in the request response signal received from the portable device 2 and the portable device identification code registered in the registration unit 101. The code verification unit 104 sends the authentication result to the locking / unlocking permission unit 105.

  When the lock / unlock permission unit 105 acquires an authentication result indicating that the authentication has been established from the code verification unit 104, the lock / unlock permission unit 105 sends a signal permitting locking / unlocking of each vehicle door to the body ECU 17. When the locking / unlocking of each vehicle door is permitted, the body ECU 17 starts energization to the touch sensor provided on the outer door handle of each vehicle door, and enters a standby state in which the user can detect the door handle operation. When the body ECU 17 detects that the user has touched the touch sensor, the body ECU 17 outputs a drive signal to the door lock motor to lock and unlock each vehicle door.

  Although description is omitted in the present embodiment, when permission to start the traveling drive source is given, for example, when it is detected that the vehicle door is opened and closed within a certain time from the unlocking, the unlocking and unlocking is performed. As in the case of permission, authentication may be performed by code verification using wireless communication. And when authentication is materialized, a permission signal may be sent to ECU which controls a traveling drive source, and it may be made into the starting standby state of a traveling drive source.

<Smart-related processing when boarding in verification ECU 10>
Next, a process related to the smart function executed by the verification ECU 10 when boarding (hereinafter referred to as a “smart-related process when boarding”) will be described with reference to the flowchart of FIG. The flowchart of FIG. 3 is started when the vehicle door is locked, for example, and is repeatedly executed at a predetermined cycle such as every 250 msec until the vehicle door is unlocked.

  First, in step S <b> 1, the transmission processing unit 102 transmits a WAKE signal from the first LF transmission antenna 11 via the first LF transmission unit 12 using radio waves having the frequency f <b> 1. In step S2, when the WAKE response signal from the portable device 2 is received by the reception processing unit 103 via the UHF receiving unit 16 (YES in S2), the process proceeds to step S3. On the other hand, if not received (NO in S2), the boarding smart-related processing is terminated.

  In step S3, the transmission processing unit 102 transmits the request signal from the first LF transmission antenna 11 via the first LF transmission unit 12 using radio waves having the frequency f1, and at the same time, the second LF transmission antenna via the second LF transmission unit 14. 13 causes the intermodulation signal to be transmitted by radio waves of frequency f2. In step S4, if the reception processing unit 103 receives the request response signal from the portable device 2 via the UHF receiving unit 16 (YES in S4), the process proceeds to step S5. On the other hand, if not received (NO in S4), the boarding smart-related processing is terminated.

  In step S5, the code verification unit 104 performs code verification using the portable device identification code included in the request response signal. If the code verification is established (YES in S5), the process proceeds to step S6 assuming that the authentication is established. On the other hand, when the code verification is not established (NO in S5), it is determined that the authentication is not established, and the boarding smart-related process is terminated. In step S <b> 6, the locking / unlocking permission unit 105 sends a signal permitting locking / unlocking of each vehicle door to the body ECU 17.

<Schematic configuration of portable device 2>
Next, the portable device 2 will be described with reference to FIG. As shown in FIG. 4, the portable device 2 includes a first LF reception antenna 21, an LF reception unit 22, a first reception intensity specifying unit 23, a second LF reception antenna 24, a second reception intensity specifying unit 25, a comparison calculation unit 26, A UHF transmission antenna 27, a UHF transmission unit 28, and a control unit 29 are provided. The portable device 2 is in a sleep state in which the power consumption is significantly lower than that in the wake-up state until the LF receiving unit 22 receives the WAKE signal, while the LF receiving unit 22 receives the WAKE signal. It shall be in a wake-up state.

  The first LF receiving antenna 21 is an antenna for receiving a signal transmitted by a radio wave having a frequency f1. The LF receiving unit 22 demodulates the WAKE signal and the request signal received by the first LF receiving antenna 21 and outputs them to the control unit 29. Therefore, the first LF reception antenna 21 corresponds to the request reception antenna of the claims. The first received strength specifying unit 23 specifies the received signal strength of the signal received by the first LF receiving antenna 21 using a known RSSI circuit or the like. The first received intensity specifying unit 23 corresponds to the required signal intensity specifying unit in the claims.

  The second LF receiving antenna 24 is an antenna for receiving a signal transmitted by a radio wave having a frequency f3 (hereinafter referred to as an intermodulation wave) generated by the third-order intermodulation distortion between the frequency f1 and the frequency f2. The frequency f3 of the intermodulation wave may be 2 × frequency f1−frequency f2 or 2 × frequency f2−frequency f1. The second LF receiving antenna 24 corresponds to the modulated wave receiving antenna of the claims. The second received intensity specifying unit 25 specifies the received signal intensity of the signal received by the second LF receiving antenna 24 using a known RSSI circuit or the like. The second received intensity specifying unit 25 corresponds to the modulated wave signal intensity specifying unit in the claims.

  The comparison calculation unit 26 increases the received signal strength specified by the first received strength specifying unit 23 with respect to the received signal strength set in advance as the received signal strength of the normal signal received by the first LF receiving antenna 21 (hereinafter referred to as the received signal strength). , Increase in transmission wave). Further, the comparison calculation unit 26 increases the received signal strength specified by the second received strength specifying unit 25 with respect to the received signal strength set in advance as the received signal strength of the normal signal received by the second LF receiving antenna 24. (Hereinafter referred to as an increase in intermodulation wave) is calculated. The legitimate signal here refers to a signal received directly from the vehicle-side unit 1 that is not for unauthorized authentication using wireless communication such as a relay attack using a repeater.

  The received signal strength of a normal signal received by the first LF receiving antenna 21 is a received signal strength estimated when a normal signal is received by the first LF receiving antenna 21 in the short-range wireless communication area. A configuration may be adopted in which data stored in advance in a nonvolatile memory is read out and used. This received signal strength may be obtained experimentally in advance or may be obtained by simulation. The received signal strength of the normal signal received by the second LF receiving antenna 24 may be the same as the received signal strength of the normal signal received by the first LF receiving antenna 21.

  Further, the comparison calculation unit 26 compares a difference obtained by subtracting the calculated increase in the transmission wave from the calculated increase in the intermodulation wave with a predetermined threshold (hereinafter referred to as a comparison threshold). The threshold value for comparison here refers to the difference obtained by subtracting the increase in the transmission wave from the increase in the intermodulation wave when the signal is directly received from the vehicle-side unit 1 without passing through the repeater, and through the repeater. The threshold value can be distinguished from this difference in the case. This comparison threshold corresponds to the first threshold of the claims.

  Here, with reference to FIG. 5, a description will be given of the difference obtained by subtracting the transmission wave increase from the intermodulation wave increase when the signal is directly received from the vehicle-side unit 1 and the difference when the signal passes through the repeater. I do. The vertical axis in FIG. 5 indicates the received signal strength, and the horizontal axis indicates the frequency. Further, FIG. 5 shows an example in which the RE passes through the repeater, shows an example in which the RN does not pass through the repeater, and IMD shows the third-order intermodulation distortion. Further, A in FIG. 5 indicates an increase in transmission wave, and B indicates an increase in intermodulation wave. In the example of FIG. 5, the transmission wave increase and the intermodulation wave increase in the case of passing through the repeater are shown.

  When the signal of frequency f1 and the signal of frequency f2 are received by the portable device 2 at the same timing, third-order intermodulation distortion occurs in the frequency f3 as shown in FIG. Further, for the purpose, the repeater amplifies the signal with an amplifier and performs transmission, so that the signal of the frequency f1 and the frequency f2 passed through the repeater and the signal of the frequency f3 generated by these signals are amplified. However, the signal of the frequency f3 due to the third-order intermodulation distortion has a characteristic that the received signal strength is significantly increased when the signal is amplified by the amplifier, compared to the signals of the frequency f1 and the frequency f2. Therefore, compared with the case where it does not pass through the repeater, when it passes through the repeater, there is a large difference between the increase in the transmission wave and the increase in the intermodulation wave as shown in FIGS.

  In this embodiment, using such characteristics, whether the signal received by the portable device 2 has passed through the repeater depends on whether the difference obtained by subtracting the transmission wave increase from the intermodulation wave increase is equal to or greater than the comparison threshold. It is possible to perform processing according to whether or not.

  The UHF transmission antenna 27 is an antenna for transmitting a signal using radio waves in the UHF band. The UHF transmission unit 28 transmits a WAKE response signal and a request response signal including a portable device identification code via the UHF transmission antenna 27. The UHF transmission unit 28 corresponds to a reply unit in the claims.

  The control unit 29 includes a processor, a volatile memory, a non-volatile memory, an I / O, and a bus for connecting them, and executes various processes related to the smart function by executing a control program stored in the non-volatile memory. Run. Details will be described later. Note that some or all of the functions executed by the control unit 29 may be configured in hardware by one or a plurality of ICs.

<Mobile-side smart-related processing in the portable device 2>
Next, processing related to the smart function in the portable device 2 (hereinafter referred to as portable smart related processing) will be described with reference to the flowchart of FIG. The flowchart of FIG. 6 may be configured to be started when, for example, the WAKE request signal is received by the LF receiving unit 22 and the portable device 2 enters the wake-up state.

  First, in step S <b> 21, the control unit 29 transmits a WAKE response signal to the UHF transmission unit 28 and causes the UHF transmission antenna 27 to transmit the WAKE response signal. In step S22, when the request signal transmitted from the vehicle unit 1 can be received by the first LF receiving antenna 21 within a predetermined time (YES in S22), the process proceeds to step S23. On the other hand, if it cannot be received within a certain time (NO in S22), the process proceeds to step S27. The control unit 29 may determine whether or not the request signal is received by the first LF receiving antenna 21 based on the input from the LF receiving unit 22. The fixed time here is a value that can be arbitrarily set.

  When the request signal can be received by the first LF receiving antenna 21, the above-mentioned intermodulation wave signal can also be received by the second LF receiving antenna 24. In this case, the first received strength specifying unit 23 specifies the received signal strength of the request signal received by the first LF receiving antenna 21, and the second received strength specifying unit 25 receives the intermodulation wave received by the second LF receiving antenna 24. The received signal strength of the signal is identified.

  In step S23, the control unit 29 performs code verification between the vehicle identification code included in the request signal received in S21 and the vehicle identification code for the legitimate user's vehicle registered in advance in the nonvolatile memory. . If the code verification is established (YES in S23), the process proceeds to step S24. On the other hand, if the code verification is not established (NO in S23), the process proceeds to S27.

  In step S25, the comparison calculation unit 26 uses the received signal strength specified by the first received strength specifying unit 23 and the received signal strength specified by the second received strength specifying unit 25 to The intermodulation wave increase is calculated. Further, the comparison calculation unit 26 compares the difference obtained by subtracting the calculated transmission wave increase from the calculated intermodulation wave increase with the comparison threshold. If the difference is equal to or greater than the comparison threshold value (YES in S25), the process proceeds to step S27. On the other hand, if the difference is less than the comparison threshold value (NO in S25), the process proceeds to S26.

  In step S <b> 26, the control unit 29 sends a request response signal including the portable device identification code to the UHF transmission unit 28, and causes the UHF transmission antenna 27 to transmit this request response signal. In step S27, when the portable device 2 shifts to the sleep state (YES in S27), the portable side smart-related process is terminated. On the other hand, if the portable device 2 is in the wake-up state (NO in S27), the process returns to step S22 and is repeated.

  In the mobile-side smart-related processing in the portable device 2, the control unit 29 establishes code verification of the vehicle identification code when the difference obtained by subtracting the transmission wave increase from the intermodulation wave increase is equal to or greater than the comparison threshold. Even in such a case, processing is performed in which the request response signal including the portable device identification code is not sent to the UHF transmitter 28. Therefore, the control unit 29 corresponds to the fraud handling unit in the claims. Further, when the difference is less than the comparison threshold value and the code verification of the vehicle identification code is established, the control unit 29 sends a request response signal including the portable device identification code to the UHF transmission unit 28. Will be processed. On the other hand, when the difference is less than the comparison threshold value and the code verification of the vehicle identification code is not established, a process of not causing the UHF transmission unit 28 to transmit the request response signal including the portable device identification code Will do.

  In the flowchart of FIG. 6, the configuration in which the processing in the comparison calculation unit 26 in S24 to S25 is performed when the code collation in S23 is established is not necessarily limited thereto. For example, if the difference obtained by subtracting the transmission wave increase calculated from the intermodulation wave increase is equal to or greater than the comparison threshold by performing the processing in the comparison calculation unit 26 in S24 to S25, the code verification in S23 is performed. Instead, the configuration may be shifted to S27. On the other hand, if the difference is less than the comparison threshold, the code collation of S23 is performed. If the code collation is established, the process proceeds to S26, and if the code collation is not established, the process proceeds to S27. .

<Summary of Embodiment 1>
According to the configuration of the first embodiment, as described above, when the signal received by the portable device 2 passes through the repeater, the difference obtained by subtracting the transmission wave increase from the intermodulation wave increase is equal to or greater than the first threshold. On the other hand, if it has not passed through the repeater, this difference is less than the first threshold. According to the configuration of the first embodiment, when this difference is greater than or equal to the first threshold value, the request response signal including the portable device identification code is not transmitted to the UHF transmission unit 28, and therefore fraud using a repeater is attempted. Authentication can be prevented from being established. Since the signal to be transmitted must be amplified for the purpose of the relay attack repeater, according to the configuration of the first embodiment, unauthorized authentication using wireless communication can be more reliably prevented.

(Embodiment 2)
In the first embodiment, the configuration using the increase in the transmission wave of the signal of the frequency f1 as the increase in the transmission wave is shown. However, the configuration is not necessarily limited thereto. For example, a configuration (hereinafter referred to as Embodiment 2) that uses an increase in the transmission wave of the signal of frequency f2 as the increase in the transmission wave may be used. Hereinafter, an example of the configuration of the second embodiment will be described. The authentication system 3 of the second embodiment is the same as the authentication system 3 of the first embodiment, except that the mobile device 2a is included instead of the mobile device 2.

  Here, the portable device 2a will be described with reference to FIG. As shown in FIG. 7, the portable device 2a includes a first LF reception antenna 21, an LF reception unit 22, a second LF reception antenna 24, a second reception intensity specifying unit 25, a comparison calculation unit 26a, a UHF transmission antenna 27, and a UHF transmission unit. 28, a control unit 29, a third LF reception antenna 30, and a third reception intensity specifying unit 31. The portable device 2 a does not include the first reception strength specifying unit 23, includes the third LF reception antenna 30 and the third reception strength specification unit 31, and includes a comparison calculation unit 26 a instead of the comparison calculation unit 26. Is the same as the portable device 2 of the first embodiment.

  The third LF receiving antenna 30 is an antenna for receiving an intermodulation signal transmitted by a radio wave having a frequency f2. The third LF receiving antenna 30 corresponds to the signal receiving antenna of the claims. The third received strength specifying unit 31 specifies the received signal strength of the signal received by the third LF receiving antenna 30 using a known RSSI circuit or the like. The third received intensity specifying unit 31 corresponds to the signal intensity specifying unit of the claims.

  The comparison calculation unit 26a uses the increase in the received signal strength specified by the third received strength specifying unit 31 instead of the increase in the received signal strength specified by the first received strength specifying unit 23 as the increase in the transmission wave. Is the same as that of the comparison operation unit 26 of the first embodiment. The comparison calculation unit 26a calculates an increase of the received signal strength specified by the third received strength specifying unit 31 with respect to the received signal strength set in advance as the received signal strength of the normal signal received by the third LF receiving antenna 30. To do.

  The comparison calculation unit 26a compares the difference obtained by subtracting the transmission wave increase for the reception signal intensity specified by the third reception intensity specifying unit 31 from the intermodulation wave increase, and the comparison threshold value. The comparison threshold mentioned here may be the same value as the comparison threshold described in the first embodiment when the transmission strength of the signal of frequency f2 is approximately the same as the transmission strength of the signal of frequency f1. . If not, the difference obtained by subtracting the transmission wave increase for the received signal intensity specified by the third reception intensity specifying unit 31 from the intermodulation wave increase without passing through the repeater, and the case of passing through the repeater What is necessary is just to set it as the threshold value which can distinguish this difference.

  As described above, the signal of the frequency f3 caused by the third-order intermodulation distortion has a characteristic that the received signal strength is increased when the signal is amplified by the amplifier as compared with the signals of the frequency f1 and the frequency f2. Therefore, even when the transmission wave increase for the reception signal strength of the frequency f2 signal is used instead of the transmission wave increase for the reception signal strength of the frequency f1 signal, as in the first embodiment, wireless communication is performed. It is possible to more reliably prevent unauthorized authentication that has been used.

(Embodiment 3)
In the first and second embodiments, the configuration using the received signal strength specified by the first received strength specifying unit 23 and the received signal strength specified by the third received strength specifying unit 31 is shown, but the configuration is not necessarily limited thereto. For example, a configuration that does not use these received signal strengths (hereinafter, Embodiment 3) may be employed. Hereinafter, an example of the configuration of the third embodiment will be described. The authentication system 3 of the third embodiment is the same as the authentication system 3 of the first embodiment, except that the mobile device 2b is included instead of the mobile device 2.

  Here, the portable device 2b will be described with reference to FIG. As shown in FIG. 8, the portable device 2b includes a first LF reception antenna 21, an LF reception unit 22, a second LF reception antenna 24, a second reception intensity specifying unit 25, a comparison calculation unit 26b, a UHF transmission antenna 27, and a UHF transmission unit. 28 and a control unit 29b. The portable device 2b is the portable device according to the first embodiment except that the first reception strength specifying unit 23 is not provided and that the comparison calculation unit 26b and the control unit 29b are provided instead of the comparison calculation unit 26 and the control unit 29. Similar to machine 2.

  The comparison calculation unit 26b compares the received signal strength of the signal having the frequency f3 (that is, the signal of the intermodulation wave) specified by the second received strength specifying unit 25 with a predetermined threshold value. The predetermined threshold value here is a threshold value that can distinguish between the received signal strength when the signal is directly received from the vehicle-side unit 1 without going through the repeater and the received signal strength when going through the repeater. do it. This predetermined threshold corresponds to the second threshold in the claims.

  Here, the received signal strength of the intermodulation wave signal when the signal is directly received from the vehicle side unit 1 and the received signal strength when the signal passes through the repeater will be described with reference to FIG. . The vertical axis in FIG. 9 indicates the received signal strength, the horizontal axis indicates the frequency, and Th indicates a predetermined threshold value. Further, symbols other than Th in FIG. 9 are the same as those described in FIG. As shown in FIG. 9, the signal of the frequency f3 due to the third-order intermodulation distortion has a characteristic that the received signal strength is greatly increased when the signal is amplified by the amplifier. Therefore, as shown in FIG. 9, it is possible to easily set a threshold value that can accurately distinguish the received signal strength when not passing through the repeater and the received signal strength when passing through the repeater.

  In the present embodiment, using such characteristics, the signal received by the portable device 2b is relayed depending on whether the received signal strength of the signal of the frequency f3 specified by the second received strength specifying unit 25 is equal to or higher than a predetermined threshold. It is possible to perform processing according to whether or not it has passed through a vessel.

  The control unit 29b is the same as the control unit 29 of the first embodiment except that the comparison result in the comparison calculation unit 26b is used instead of the comparison result in the comparison calculation unit 26. The control unit 29b also corresponds to the fraud handling unit in the claims. When the received signal strength of the signal of the frequency f3 specified by the second received strength specifying unit 25 is equal to or greater than a predetermined threshold, the control unit 29b sends a request response signal including the portable device identification code to the UHF transmitting unit 28. Do not let the process. This process may be performed when code verification of the vehicle identification code is established, or may be performed before code verification of the vehicle identification code.

  According to the configuration of the third embodiment, as described above, when the signal received by the portable device 2b passes through the repeater, the received signal strength of the signal of the frequency f3 specified by the second received strength specifying unit 25 is On the other hand, when it is not less than the predetermined threshold, it is less than the predetermined threshold when it does not pass through the repeater. According to the configuration of the third embodiment, the request response signal including the portable device identification code is not transmitted to the UHF transmission unit 28 when the received signal strength exceeds a predetermined threshold value. Authentication can be prevented from being established. Since the signal to be transmitted must be amplified for the purpose of the relay attack repeater, the configuration of the third embodiment can more reliably prevent unauthorized authentication using wireless communication.

(Embodiment 4)
In the first embodiment, the configuration using the difference obtained by subtracting the transmission wave increase from the intermodulation wave increase is shown, but the configuration is not necessarily limited thereto. For example, a configuration using a difference obtained by subtracting the received signal strength specified by the first received strength specifying unit 23 from the received signal strength specified by the second received strength specifying unit 25 (hereinafter, a fourth embodiment) may be employed. Hereinafter, an example of the configuration of the fourth embodiment will be described. The authentication system 3 according to the fourth embodiment is the same as the authentication system 3 according to the first embodiment except that the portable device 2c is included instead of the portable device 2.

  Here, the portable device 2c will be described with reference to FIG. As shown in FIG. 10, the portable device 2c includes a first LF reception antenna 21, an LF reception unit 22, a second LF reception antenna 24, a second reception intensity specifying unit 25, a comparison calculation unit 26c, a UHF transmission antenna 27, and a UHF transmission unit. 28 and a control unit 29c. The portable device 2c is the same as the portable device 2 of the first embodiment except that the comparison calculation unit 26c and the control unit 29c are provided instead of the comparison calculation unit 26 and the control unit 29.

  The comparison calculation unit 26c receives the signal of the frequency f1 specified by the first reception intensity specifying unit 23 from the reception signal intensity of the signal of the frequency f3 specified by the second reception intensity specifying unit 25 (that is, the signal of the intermodulation wave). The difference obtained by subtracting the signal intensity is calculated. Then, the calculated difference is compared with a predetermined threshold value. The predetermined threshold here is a difference obtained by subtracting the reception signal strength of the frequency f1 from the reception signal strength of the intermodulation wave when the signal is directly received from the vehicle-side unit 1 without passing through the repeater. What is necessary is just to set it as the threshold value which can distinguish this difference at the time of passing through a repeater. This predetermined threshold corresponds to the third threshold in the claims.

  Here, using FIG. 11, the difference obtained by subtracting the received signal strength of the frequency f1 from the received signal strength of the intermodulation wave when the signal is directly received from the vehicle-side unit 1, and this when the signal passes through the repeater The difference will be described. The vertical axis in FIG. 11 indicates the received signal strength, and the horizontal axis indicates the frequency. Further, C in FIG. 11 shows the difference in received signal strength between the intermodulation wave and the frequency f1 when passing through the repeater, and this difference when D does not pass through the repeater. Symbols other than C and D in FIG. 11 are the same as described in FIG. As described above, the signal of the frequency f3 due to the third-order intermodulation distortion has a characteristic that the received signal strength is significantly increased when the signal is amplified by the amplifier, compared to the signals of the frequency f1 and the frequency f2. Therefore, the difference obtained by subtracting the received signal strength of the frequency f1 from the received signal strength of the intermodulation wave is smaller when passing through the repeater than when not going through the repeater, as shown in C and D of FIG. .

  In the present embodiment, using such characteristics, the signal received by the portable device 2c is relayed depending on whether or not the difference obtained by subtracting the received signal strength of the frequency f1 from the received signal strength of the intermodulation wave is equal to or less than a predetermined threshold value. It is possible to perform processing according to whether or not it has passed through a vessel.

  The control unit 29c is the same as the control unit 29 of the first embodiment except that the comparison result in the comparison calculation unit 26c is used instead of the comparison result in the comparison calculation unit 26. The control unit 29c also corresponds to the fraud handling unit in the claims. When the difference obtained by subtracting the reception signal strength of the frequency f1 from the reception signal strength of the intermodulation wave is equal to or less than a predetermined threshold value, the control unit 29c sends a request response signal including the portable device identification code to the UHF transmission unit 28. Do not let the process. This process may be performed when code verification of the vehicle identification code is established, or may be performed before code verification of the vehicle identification code.

  According to the configuration of the fourth embodiment, as described above, when the signal received by the portable device 2c passes through the repeater, the difference obtained by subtracting the received signal strength of the frequency f1 from the received signal strength of the intermodulation wave is obtained. On the other hand, the value is equal to or less than the predetermined threshold value, and is greater than the predetermined threshold value when the signal does not pass through the repeater. According to the configuration of the fourth embodiment, when this difference is equal to or smaller than a predetermined threshold value, the request response signal including the portable device identification code is not transmitted to the UHF transmission unit 28. Therefore, fraud using a repeater has been attempted. In some cases, authentication can not be established. Since the signal to be transmitted must be amplified for the purpose of the relay attack repeater, even with the configuration of the fourth embodiment, unauthorized authentication using wireless communication can be more reliably prevented.

(Embodiment 5)
In the fourth embodiment, the configuration is shown in which the difference obtained by subtracting the received signal strength of the frequency f1 from the received signal strength of the intermodulation wave is compared with the predetermined threshold, but this is not necessarily the case. For example, a configuration in which a difference obtained by subtracting the received signal strength of the frequency f2 from the received signal strength of the intermodulation wave is compared with a predetermined threshold (hereinafter, Embodiment 5) may be employed. Hereinafter, an example of the configuration of the fifth embodiment will be described. The authentication system 3 according to the fifth embodiment is the same as the authentication system 3 according to the first embodiment except that the portable device 2d is included instead of the portable device 2.

  Here, the portable device 2d will be described with reference to FIG. As illustrated in FIG. 12, the portable device 2d includes a first LF reception antenna 21, an LF reception unit 22, a second LF reception antenna 24, a second reception intensity specifying unit 25, a comparison calculation unit 26d, a UHF transmission antenna 27, and a UHF transmission unit. 28, a control unit 29d, a third LF reception antenna 30, and a third reception intensity specifying unit 31. The portable device 2d does not include the first reception intensity specifying unit 23, includes the third LF reception antenna 30 and the third reception intensity specifying unit 31, and a comparison calculation unit instead of the comparison calculation unit 26 and the control unit 29. Except for the point provided with 26d and the control part 29d, it is the same as that of the portable device 2 of Embodiment 1.

  The third LF reception antenna 30 and the third reception intensity specifying unit 31 are the same as those described in the second embodiment. The comparison calculation unit 26d uses a difference obtained by subtracting the reception signal strength of the frequency f2 from the reception signal strength of the intermodulation wave instead of the difference obtained by subtracting the reception signal strength of the frequency f1 from the reception signal strength of the intermodulation wave. Except for this, it is the same as the comparison operation unit 26c of the fourth embodiment. The comparison calculation unit 26d subtracts the received signal strength specified by the third received strength specifying unit 31 from the received signal strength of the signal of the frequency f3 specified by the second received strength specifying unit 25 (that is, the signal of the intermodulation wave). Calculate the difference.

  Then, the comparison calculation unit 26d compares the difference obtained by subtracting the reception signal strength of the frequency f2 from the reception signal strength of the intermodulation wave with a predetermined threshold value. The predetermined threshold mentioned here may be the same value as the predetermined threshold described in the fourth embodiment when the transmission intensity of the signal of frequency f2 is approximately the same as the transmission intensity of the signal of frequency f1. . If not, the difference obtained by subtracting the received signal strength of the frequency f2 from the received signal strength of the intermodulation wave when the signal is directly received without passing through the repeater, and this difference when passing through the repeater And a threshold that can be distinguished from each other.

  The control unit 29d is the same as the control unit 29 of the first embodiment except that the comparison result in the comparison calculation unit 26d is used instead of the comparison result in the comparison calculation unit 26. The control unit 29d also corresponds to the fraud handling unit in the claims. When the difference obtained by subtracting the reception signal strength of the frequency f2 from the reception signal strength of the intermodulation wave is equal to or less than a predetermined threshold, the control unit 29d sends a request response signal including the portable device identification code to the UHF transmission unit 28. Do not let the process. This process may be performed when code verification of the vehicle identification code is established, or may be performed before code verification of the vehicle identification code.

  As described above, the signal of the frequency f3 caused by the third-order intermodulation distortion has a characteristic that the received signal strength is increased when the signal is amplified by the amplifier as compared with the signals of the frequency f1 and the frequency f2. Therefore, even when the difference obtained by subtracting the reception signal strength of the frequency f2 from the reception signal strength of the intermodulation wave is used instead of the difference obtained by subtracting the reception signal strength of the frequency f1 from the reception signal strength of the intermodulation wave, the embodiment As in the case of 4, unauthorized authentication using wireless communication can be more reliably prevented.

(Embodiment 6)
In the above-described embodiment, the unlocking and unlocking and the engine starting are shown as the types of vehicle control that is permitted by the smart function, but are not necessarily limited thereto. For example, it is good also as a structure which makes object control of vehicles other than locking / unlocking and engine starting.

(Embodiment 7)
In the above-described embodiment, an example in which the portable devices 2, 2a, 2b, and 2c are electronic keys has been shown, but the present invention is not necessarily limited thereto. For example, the portable devices 2, 2a, 2b, and 2c may be portable terminals such as multifunctional mobile phones that also function as electronic keys.

(Embodiment 8)
In the above-described embodiment, the configuration in which the request response signal including the portable device identification code is not transmitted is shown as processing for unauthorized authentication using wireless communication in the control units 29, 29b, and 29c. Not limited to. For example, the UHF transmitter 28 may be configured to transmit a signal indicating that unauthorized authentication using wireless communication has been attempted. In addition, a signal indicating that authentication should not be established, such as an NG command, may be transmitted to the UHF transmission unit 28. When these configurations are adopted, the code verification unit 104 of the verification ECU 10 may be configured not to establish code verification when these signals are received by the UHF reception unit 16.

(Embodiment 9)
In the above-described embodiment, the configuration in which the authentication system 3 is applied to a vehicle has been described. However, the configuration is not limited to this, and the configuration may be applied to other than the vehicle. For example, it may be configured to be applied to a house or facility that uses wireless communication for locking and unlocking a door.

  The present invention is not limited to the above-described embodiments and modifications, and various modifications are possible within the scope of the claims, and technical means disclosed in different embodiments and modifications, respectively. Embodiments obtained by appropriately combining the above are also included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Vehicle side unit, 2, 2a, 2b, 2c, 2d Portable machine, 3 Authentication system, 10 Verification ECU (master apparatus, in-vehicle apparatus), 21 1st LF receiving antenna (request receiving antenna), 23 1st receiving intensity specific | specification part (Requested signal strength specifying unit), 24 Second LF receiving antenna (modulated wave receiving antenna), 25 Second receiving strength specifying unit (modulated wave signal strength specifying unit), 28 UHF transmitting unit (reply unit), 29, 29b, 29c , 29d Control unit (fraud handling unit), 30 3rd LF receiving antenna (signal receiving antenna), 31 3rd received strength specifying unit (signal strength specifying unit), 102 transmission processing unit, 104 code verification unit (authentication unit)

Claims (10)

A master device (10) including a transmission processing unit (102) for transmitting a request signal for requesting code verification by wireless communication at a predetermined frequency f1,
A portable device (2, 2a, 2b, 2c, 2d) provided with a reply unit (28) that is carried by the user and transmits a response signal including an identification code for identifying the device itself in response to the request signal Including
The master device is
An authentication system including an authentication unit (104) that performs authentication by code verification using an identification code included in a response signal transmitted from the reply unit,
The transmission processing unit transmits a request signal at a frequency f1, and at the same time, transmits a predetermined signal by radio communication at a frequency f2 different from the frequency f1,
The portable device is
A request receiving antenna (21) for receiving a request signal transmitted at the frequency f1,
A modulated wave receiving antenna (24) for receiving a signal of the frequency f3 generated by the third-order intermodulation distortion of the frequency f1 and the frequency f2,
A modulated wave signal strength identifying unit (25) for identifying a signal strength of a signal received by the modulated wave receiving antenna;
An authentication system comprising: a fraud handling unit (29, 29b, 29c, 29d) that performs processing for unauthorized authentication using wireless communication based on the signal strength specified by the modulated wave signal strength specifying unit. In claim 1,
The authentication system, wherein the frequency f3 is a value obtained by subtracting the frequency f2 from a value twice the frequency f1, or a value obtained by subtracting the frequency f1 from a value twice the frequency f2. In claim 1 or 2,
The portable device (2)
A request signal strength specifying unit (23) for specifying the signal strength of the request signal received by the request receiving antenna;
The fraud handling unit (29) is configured to increase the signal strength specified by the modulated wave signal strength specifying unit with respect to a signal strength set in advance as a signal strength of a normal signal received by the modulated wave receiving antenna. The value obtained by subtracting an increase in the signal strength specified by the request signal strength specifying unit from the signal strength set in advance as the signal strength of the normal request signal received by the request receiving antenna is equal to or greater than the first threshold. An authentication system that performs processing against unauthorized authentication using wireless communication. In claim 1 or 2,
The fraud handling unit (29b) is an authentication system that performs processing for fraudulent authentication using wireless communication when the signal strength specified by the modulated wave signal strength specifying unit is equal to or greater than a second threshold. In claim 1 or 2,
The portable device (2c)
A request signal strength specifying unit (23) for specifying a signal strength of a request signal received by the request receiving antenna;
When the value obtained by subtracting the signal strength specified by the modulated wave signal strength specifying unit from the signal strength specified by the required signal strength specifying unit is less than a third threshold, the fraud handling unit (29c) An authentication system that performs processing against unauthorized authentication using wireless communication. In claim 1 or 2,
The portable device (2a, 2d)
A signal receiving antenna (30) for receiving a signal transmitted at the frequency f2,
A signal strength specifying unit (31) for specifying a signal strength of a signal received by the signal receiving antenna;
The fraud handling unit (29, 29d) performs processing for unauthorized authentication using wireless communication based on the signal strength specified by the signal strength specifying unit and the signal strength specified by the modulated wave signal strength specifying unit. Authentication system. In any one of Claims 1-6,
An authentication system in which the fraud handling unit performs a process of preventing the response signal including the identification code from being transmitted even when the request signal is received, as a process for unauthorized authentication using wireless communication. In any one of Claims 1-6,
The fraud handling unit indicates a signal indicating that unauthorized authentication using wireless communication has been attempted as a process for unauthorized authentication using wireless communication, or indicates that authentication must not be established. An authentication system for performing processing for transmitting a signal to the master device. In any one of Claims 1-8,
The master device is an in-vehicle device used in a vehicle,
The authentication unit is an authentication system that performs authentication for permitting control of the vehicle. Wireless communication between a master device (10) that transmits a request signal for requesting code verification at a predetermined frequency f1 by wireless communication and a portable device (2, 2a, 2b, 2c, 2d) carried by the user Used in the vehicle authentication system (3) that performs authentication by code verification used,
A request receiving antenna (21) for receiving a request signal transmitted at the frequency f1,
A frequency f3 generated by third-order intermodulation distortion between the frequency f2 different from the frequency f1 and the frequency f1, which is the frequency of the signal transmitted at the same time as the request signal is transmitted at the frequency f1 by the master device. A modulated wave receiving antenna (24) for receiving a signal;
A modulated wave signal strength identifying unit (25) for identifying a signal strength of a signal received by the modulated wave receiving antenna;
A portable device comprising a fraud handling unit (29, 29b, 29c, 29d) that performs processing for unauthorized authentication using wireless communication based on the signal strength specified by the modulated wave signal strength specifying unit.

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