JP6822817B2 - Key authentication system - Google Patents

Description

The present invention relates to a key authentication system that synchronizes rolling code values while performing key authentication by wireless communication between a device and a portable device.

Vehicles to which the so-called smart key system (registered trademark) is applied perform key authentication by two-way communication with the portable device owned by the user, and unlock the door on condition that the key authentication is established. .. Further, when the unlock switch of the portable device is turned on, the rolling code value of the portable device is updated, and a wireless signal including the rolling code value is transmitted from the portable device. In this case, the vehicle performs key authentication by unidirectional communication with the portable device as the transmitting side, unlocks the door on the condition that the key authentication is established, and rolls the rolling code value of the vehicle on the portable device. Synchronize with the code value. A technique for updating the rolling code value when the switch of the portable device is turned on is described in, for example, Patent Document 1.

Japanese Unexamined Patent Publication No. 2011-59931 (paragraph [0038])

Assuming that unidirectional communication has not been established for a long period of time, if the switch of the portable device is turned on many times, the rolling code value of the portable device will be updated each time the switch is turned on, and the vehicle and the portable device will be updated. The difference value of the rolling code value of the above exceeds a predetermined threshold value. In this case, if the key authentication is performed on the condition that a specific operation is performed on the switch, the user feels annoyed.

The present invention has been made by paying attention to such a problem, and an object of the present invention is to provide a key authentication system capable of preventing a decrease in convenience.

The key authentication system that solves the above problems is a key authentication system that synchronizes rolling code values while performing key authentication by wireless communication between a device and a portable device. The device is a rolling code value of the portable device. The portable device is provided with a device control means for transmitting a first wireless signal requesting the above, and the portable device transmits a second wireless signal including a rolling code value of the portable device in response to the request by the first wireless signal. The gist is to provide key control means for the system.

According to this configuration, when a first wireless signal requesting the rolling code value of the portable device is transmitted from the device in the process of two-way communication, the request from the first wireless signal is received from the portable device. A second radio signal containing the rolling code value of the portable device is transmitted. Then, as the second radio signal is received by the device, the device can synchronize the rolling code value of the device with the rolling code value of the portable device included in the second radio signal. As a result, it is possible to reduce situations in which the user feels annoyed, such as performing a specific operation due to the difference value between the rolling code values of the device and the portable device. Therefore, it is possible to prevent a decrease in convenience.

Regarding the key authentication system, the portable device includes a switch for instructing the operation of the device, and the key control means updates the rolling code value of the own portable device when the switch is turned on. The updated rolling code value is stored in the memory, and when the key control means receives the first radio signal, the rolling code value is read from the memory and the second rolling code value including the rolling code value is included. It may be possible to transmit the radio signal of.

According to this configuration, the rolling code value of the device can be synchronized with the latest rolling code value of the portable device. As a result, it is possible to differentiate from the past rolling code value.

Regarding the key authentication system, the device control means transmits the first wireless signal when the key ID for which key authentication is established is acquired in connection with the transmission of the request signal requesting the key ID of the portable device. You may do it.

According to this configuration, the rolling code value can be synchronized in the state where the key authentication by the two-way communication is established. This enables reliable synchronization without missing the opportunity to synchronize.
Regarding the key authentication system, the device is a vehicle equipped with an outside switch instructing a door lock, and the device control means sends the request signal to the outside of the vehicle when the outside switch is turned on. The key control means may transmit a response signal including the key ID of the own portable device in response to the request by the request signal.

According to this configuration, the rolling code value can be synchronized when the door is locked by two-way communication. This enables synchronization in situations where the user is near the vehicle.
Regarding the key authentication system, the device is a vehicle equipped with a sensor that detects whether or not the vehicle is driving, and the device control means periodically when the sensor detects that the vehicle is driving. The request signal may be transmitted to the inside of the vehicle, and the key control means may transmit a response signal including the key ID of the own portable device in response to the request by the request signal.

According to this configuration, the rolling code value can be reliably synchronized in the situation where the portable device is in the vehicle. In addition, synchronization is possible in an environment where the rolling code value of the portable device is not easily eavesdropped.

Regarding the key authentication system, the device control means acquires a key ID for which the first key authentication of the key authentication is established in connection with transmitting a request signal requesting the key ID of the portable device, and the first key authentication means. The second radio signal is included in the alternative authentication of the second key authentication when the key authentication of 1 is established and the second key authentication different from the first key authentication is not established. The rolling code value of the device synchronized with the rolling code value of the portable device may be used.

According to this configuration, security can be improved by using the rolling code value of the device synchronized with the rolling code value of the portable device for the alternative authentication when the second key authentication is not established.

According to the present invention, it is possible to prevent a decrease in convenience.

A block diagram showing the configuration of a key authentication system. The figure which shows the process about the synchronization of the rolling code value in two-way communication.

(First Embodiment)
Hereinafter, the first embodiment of the key authentication system will be described.
As shown in FIG. 1, the key authentication system 1 is a so-called smart key system (registered trademark), which performs key authentication by two-way communication between the vehicle 2 and the portable device 3 and transmits the portable device 3. Key authentication is performed by unidirectional communication with the side, and the door of the vehicle 2 is locked or unlocked on condition that either key authentication is established. The vehicle 2 corresponds to a device.

The portable device 3 possessed as a vehicle key includes a microcomputer 31 that controls the overall control of its own key, an LF receiving circuit 32 that can receive LF band radio waves, and a UHF transmitting circuit that can transmit UHF band radio waves. It has 33.

When the WAKE signal that triggers bidirectional communication is received by the LF receiving circuit 32 among the LF band radio waves transmitted from the vehicle 2, the microcomputer 31 uses the ACK signal as the UHF band radio wave from the UHF transmission circuit 33. Send. Then, when the ACK signal is received by the vehicle 2 and the radio wave of the LF band of the next phase is received by the LF receiving circuit 32, the microcomputer 31 transmits the radio wave of the UHF band of the next phase to the UHF transmission circuit. It is transmitted from 33. In two-way communication, radio waves in the LF band and radio waves in the UHF band are transmitted and received a predetermined number of times.

In bidirectional communication, when a request signal requesting the key ID of the portable device 3 is received by the LF receiving circuit 32, the microcomputer 31 receives the request by the request signal and receives a response signal including the key ID of the portable device 3. Is transmitted from the UHF transmission circuit 33. The key ID of the portable device 3 is stored in the memory 34 in the microcomputer 31.

Then, when the response signal is analyzed by the vehicle 2 and the key IDs are collated and matched, the key authentication by two-way communication is established, and in this state, the unlocking of the door is permitted. As a result, when the user possessing the portable device 3 enters the bidirectional communication area by the radio wave of the LF band from the vehicle 2, the door is automatically unlocked by the bidirectional communication. Then, when the door handle is touched in this unlock permission state, the door is actually unlocked.

Further, the portable device 3 includes an unlock switch 35 for instructing the unlocking of the door and a lock switch 36 for instructing the lock of the door in the operation of the vehicle 2. Both the unlock switch 35 and the lock switch 36 are examples of switches that instruct the operation of the vehicle 2. The microcomputer 31 monitors the on operation of the unlock switch 35 or the lock switch 36, and when the unlock switch 35 is turned on, the operation code instructing the unlocking of the door, the above key ID, and the portable device 3 A wireless signal including the rolling code value of is transmitted from the UHF transmission circuit 33. On the other hand, when the lock switch 36 is turned on, the microcomputer 31 transmits a wireless signal including an operation code instructing the door lock, the key ID, and the rolling code value of the portable device 3 from the UHF transmission circuit 33. To do. The microcomputer 31 updates the rolling code value of the portable device 3 (incremented as an example) each time the unlock switch 35 or the lock switch 36 is turned on, and transfers the updated rolling code value to the memory 34. Remember.

Then, when each wireless signal is analyzed by the vehicle 2 and the key IDs are collated and matched, the key authentication by unidirectional communication is established. In this state, the door is unlocked or locked, and the vehicle The rolling code value of 2 is synchronized with the rolling code value of the portable device 3. As a result, when the user turns on the unlock switch 35 or the lock switch 36 of the portable device 3 in the area where the wireless signal reaches the vehicle 2 (unidirectional communication area), the door is unlocked or locked by the unidirectional communication. Will be.

In addition to the collation ECU 21 that controls the security control of the own vehicle, the vehicle 2 has an LF transmitter 22 capable of transmitting LF band radio waves, a UHF receiver 23 capable of receiving UHF band radio waves, and a touch on the door handle. It is equipped with a touch sensor 24 that detects an operation.

When the door is locked, the collation ECU 21 transmits a WAKE signal from the LF transmitter 22 to form a bidirectional communication area around the door in order to monitor the approach of the portable device 3 to the vehicle 2. Then, when the ACK signal is received by the UHF receiver 23, the collation ECU 21 transmits a radio wave in the LF band of the next phase from the LF transmitter 22, and receives the radio wave and transmits the UHF band from the portable device 3. The two-way communication is changed such that the radio wave of is received by the UHF receiver 23.

In the process of two-way communication, the collation ECU 21 transmits a request signal requesting the key ID of the portable device 3 from the LF transmitter 22, and a response signal including the key ID of the portable device 3 is transmitted by the UHF receiver 23. When received, the response signal is analyzed. The key ID of the portable device 3 is registered in the memory 25 in the collation ECU 21. Then, the collation ECU 21 collates with the key ID registered in the memory 25 when analyzing the response signal, and when the key authentication is established by collating and matching the key IDs, unlocking the door is permitted. When the collation ECU 21 detects a touch operation on the door handle through the touch sensor 24 in this unlock permission state, the collation ECU 21 actually unlocks the door.

Further, the collation ECU 21 analyzes the wireless signal when the wireless signal is received by the UHF receiver 23. Then, the collation ECU 21 first compares the rolling code values of the vehicle 2 and the portable device 3 when analyzing the wireless signal, the rolling code value of the portable device 3 is larger, and the difference value between the rolling code values of both is larger. The rolling code value of the vehicle 2 is synchronized with the rolling code value of the portable device 3 and stored in the memory 25 on condition that the value is equal to or less than the threshold value. The rolling code value of the vehicle 2 is updated every time the initial setting value is stored in the memory 25 and then synchronized with the rolling code value of the portable device 3.

Next, the collation ECU 21 collates with the key ID registered in the memory 25 when analyzing the wireless signal, and when the key authentication is established by collating and matching the key IDs, the collation ECU 21 receives an instruction by the operation code and opens the door. Unlock or lock.

According to the analysis of the wireless signal, the collation ECU 21 eavesdrops on the past wireless signal when the rolling code value of the portable device 3 is the same as the rolling code value of the vehicle 2 or the rolling code value of the portable device 3 is smaller. It does not unlock or lock the door, nor does it perform synchronization processing, as it may have been done.

Further, even if the rolling code value of the portable device 3 is larger, when the difference value between the two rolling code values exceeds the threshold value, the portable device 3 is repeatedly carried in the distance of the vehicle 2 within a short period of time or for a long period of time. It is suggested that the unlock switch 35 or the lock switch 36 of the machine 3 was turned on. Therefore, in this case, the collation ECU 21 does not unlock or lock the door at this point, does not perform the synchronization process, and later sends a wireless signal indicating that a specific operation to the unlock switch 35 or the like has been performed to the UHF. On condition that the door is received by the receiver 23, the door is unlocked and locked through key authentication, and synchronization processing is performed.

By the way, the door handle of the vehicle 2 is provided with a lock button 26 for instructing the door lock. The lock button 26 is an example of an external switch. The collation ECU 21 transmits a WAKE signal from the LF transmitter 22 when the lock button 26 is turned on, and forms a bidirectional communication area around the door outside the vehicle. Then, the collation ECU 21 performs bidirectional communication in the same manner as when the door is locked, and in the process, when the key ID for which key authentication is established is acquired by analyzing the response signal, the collation ECU 21 locks the door and carries it. A radio signal (corresponding to the first radio signal) requesting the rolling code value of the machine 3 is transmitted from the LF transmitter 22. At this time, the microcomputer 31 of the portable device 3 reads the rolling code value of the portable device 3 from the memory 34 in response to the request from the first wireless signal, and the wireless signal including the rolling code value (in the second wireless signal). (Equivalent) is transmitted from the UHF transmission circuit 33. The collation ECU 21 corresponds to the device control means, and the microcomputer 31 corresponds to the key control means.

When the second radio signal is received by the UHF receiver 23, the collation ECU 21 synchronizes the rolling code value of the vehicle 2 with the rolling code value of the portable device 3 included in the second radio signal, and then synchronizes the memory with the rolling code value of the portable device 3. Store in 25. That is, the collation ECU 21 sets the rolling code value of the vehicle 2 to the portable device 3 not only when the wireless signal is received by the UHF receiver 23 but also when the second wireless signal is received by the UHF receiver 23. It will be synchronized with the rolling code value.

Next, the operation of the key authentication system 1 will be described.
As shown in FIG. 2, in the process of bidirectional communication between the vehicle 2 and the portable device 3, a wireless signal (corresponding to the first wireless signal) requesting the rolling code value of the portable device 3 is transmitted from the vehicle 2. Then, in response to the request from the first wireless signal, the portable device 3 transmits a wireless signal (corresponding to the second wireless signal) including the rolling code value of the portable device 3. Then, as the second radio signal is received by the vehicle 2, the vehicle 2 may synchronize the rolling code value of the vehicle 2 with the rolling code value of the portable device 3 included in the second radio signal. it can.

As described above, according to the present embodiment, the following effects can be obtained.
(1) In addition to synchronizing rolling code values in the case of unidirectional communication, synchronization of rolling code values is also achieved in the case of two-way communication. As a result, it is possible to reduce situations in which the user feels annoyed, such as performing a specific operation due to the difference value between the rolling code values of the vehicle 2 and the portable device 3. Therefore, it is possible to prevent a decrease in convenience.

(2) The latest rolling code value of the portable device 3 is stored in the memory 34 of the portable device 3, and when the microcomputer 31 receives the first radio signal, the latest rolling code value is stored in the memory 34. It reads out and transmits a second radio signal including the rolling code value. According to this configuration, the rolling code value of the vehicle 2 can be synchronized with the latest rolling code value of the portable device 3. As a result, it is possible to differentiate from the past rolling code value. Therefore, it is possible to prevent theft method of illegally using the eavesdropped wireless signal.

(3) The collation ECU 21 of the vehicle 2 requests the rolling code value of the portable device 3 when the key ID for which the key authentication is established is acquired due to the transmission of the request signal requesting the key ID of the portable device 3. The first radio signal is transmitted. According to this configuration, the rolling code value can be synchronized in the state where the key authentication by the two-way communication is established. This enables reliable synchronization without missing the opportunity to synchronize.

(4) Regarding (3) above, the rolling code value can be synchronized when the door is locked by two-way communication triggered by the on operation of the lock button 26 mounted on the vehicle 2. This enables synchronization in a situation where the user is near the vehicle 2.

(5) Rolling code values can be synchronized by two-way communication without requiring user operation.
The first embodiment may be modified and embodied as follows.

-The timing for synchronizing the rolling code values is not limited to when the door is locked by two-way communication. It suffices as long as the key authentication by two-way communication is established. As an example, the vehicle 2 is equipped with a sensor 27 (see the broken line in FIG. 1) for detecting whether or not the vehicle is driving, and the matching ECU 21 detects that the sensor 27 is driving the vehicle 2. At this time, a configuration may be adopted in which a request signal is periodically transmitted into the vehicle, and the microcomputer 31 of the portable device 3 receives the request by the request signal and transmits a response signal including the key ID of the portable device 3. According to this configuration, the rolling code value can be surely synchronized in the situation where the portable device 3 is in the vehicle. In addition, synchronization is possible in an environment in which the rolling code value of the portable device 3 is unlikely to be eavesdropped.

Further, the timing for synchronizing the rolling code values is not limited to the time when the outside switch (lock button 26) instructing the door lock is pressed, but also when the in-vehicle switch instructing the engine start is pressed.

(Second Embodiment)
Next, a second embodiment of the key authentication system will be described.
In the key authentication system 1 of the second embodiment, the key authentication by two-way communication between the vehicle 2 and the portable device 3 following the first embodiment is defined as the first key authentication. When the first key authentication and the second key authentication different from the first key authentication are both established, unlocking of the door or the like is permitted. In this example, as the second key authentication, the delay time of a specific radio wave reciprocating between the vehicle 2 and the portable device 3 is measured, and the propagation distance is calculated by multiplying the delay time by a known speed of light. , Distance authentication by portable device position area authentication for estimating the distance from the vehicle 2 to the portable device 3 is adopted.

Therefore, the key IDs are collated and matched by key authentication (first key authentication) by two-way communication, and the estimated distance from the vehicle 2 to the portable device 3 is equal to or less than the threshold value by distance authentication (second key authentication). In that case, unlocking the door will be permitted. On the other hand, if the estimated distance value exceeds the threshold value, there is a possibility of fraudulent activity using the repeater, so even if the key IDs collate and match, unlocking the door or the like is not permitted.

By the way, when the above distance authentication is adopted as the second key authentication, the distance estimation accuracy may deteriorate due to the influence of the radio wave propagation environment, and the portable device 3 is actually near the vehicle 2 (LF band). Even though it is within the two-way communication area by radio waves, there is a concern that the distance estimate will exceed the threshold value and unlocking will not be permitted. In order to deal with this, even if the distance authentication (second key authentication) is not established, if the alternative authentication of the second key authentication is established, a backup means for permitting the unlocking of the door, etc. is provided. In the second embodiment, a device is devised to improve the security when the door is unlocked by the backup means.

In this example, as a backup means, a wireless unlock in which the user turns on the unlock switch 35 of the portable device 3 is adopted. Therefore, the key authentication by the one-way communication following the first embodiment is the alternative authentication of the second key authentication, and in this second embodiment, the key authentication by the one-way communication is further secure. Was made to be obtained.

That is, the collation ECU 21 of the vehicle 2 performs key authentication by unidirectional communication using the rolling code value of the vehicle 2 synchronized with the rolling code value of the portable device 3 according to the process of FIG. In addition, not only when the key IDs are collated and matched by the key authentication by two-way communication (first key authentication) and the distance authentication (second key authentication) is not established, the user can use the user in the unidirectional communication area. For all opportunities when the unlock switch 35 is turned on, key authentication by unidirectional communication may be performed using the rolling code value of the vehicle 2 synchronized last.

Next, the operation of the key authentication system 1 will be described.
With reference to FIG. 2, when the user possessing the portable device 3 enters the bidirectional communication area by the radio wave of the LF band from the vehicle 2, bidirectional communication is established between the vehicle 2 and the portable device 3. The first key authentication is established when the key IDs are collated and matched. Then, in the process of two-way communication, when a radio signal including the rolling code value of the portable device 3 is transmitted from the portable device 3 in response to a request from the vehicle 2, the rolling code value of the vehicle 2 becomes the portable device 3. Synchronized with the rolling code value.

After that, in this example, the second key authentication by the distance authentication is performed, but here, it is assumed that the second key authentication is not established. In this case, since the user cannot unlock the door even if he / she touches the door handle, he / she tries to unlock the door by a wireless unlock (backup means) that turns on the unlock switch 35 of the portable device 3. At this time, the microcomputer 31 of the portable device 3 updates the rolling code value of the portable device 3 (incremented in one example) in accordance with the on operation of the unlock switch 35, and then a wireless signal including the updated rolling code value. Is transmitted from the UHF transmission circuit 33. A wireless signal including the updated rolling code value of the portable device 3 is transmitted from the rolling code value of the portable device 3 transmitted by the portable device 3 to the vehicle 2 in the process of the immediately preceding two-way communication.

The collation ECU 21 of the vehicle 2 analyzes the wireless signal when the wireless signal is received by the UHF receiver 23. At this time, the collation ECU 21 first compares the rolling code value of the portable device 3 included in the wireless signal with the rolling code value of the vehicle 2 synchronized with the rolling code value of the portable device 3 in the process of the immediately preceding two-way communication. To do. Then, the collation ECU 21 sets the rolling code value of the vehicle 2 to the rolling code value of the portable device 3 on the condition that the rolling code value of the portable device 3 is larger and the difference value between the two rolling code values is equal to or less than the threshold value. It is stored in the memory 25 after being synchronized with the code value.

Next, the collation ECU 21 collates the key ID included in the wireless signal with the key ID registered in the memory 25, and when the key IDs collate and match, the alternative authentication of the second key authentication is established, the wireless The door is unlocked in response to the instruction from the operation code included in the signal.

According to the analysis of the wireless signal, the collation ECU 21 eavesdrops on the past wireless signal when the rolling code value of the portable device 3 is the same as the rolling code value of the vehicle 2 or the rolling code value of the portable device 3 is smaller. Since it may have been done, the door will not be unlocked and the synchronization process will not be performed.

Further, even if the rolling code value of the portable device 3 is larger, when the difference value between the two rolling code values exceeds the threshold value, the portable device 3 is repeatedly carried in the distance of the vehicle 2 within a short period of time or for a long period of time. It is suggested that the unlock switch 35 or the lock switch 36 of the machine 3 was turned on. Therefore, in this case, the collation ECU 21 does not unlock the door at this point, does not perform the synchronization process, and later sends a wireless signal indicating that a specific operation to the unlock switch 35 or the like has been performed to the UHF receiver. On the condition that it is received in 23, the door is unlocked and the synchronization process is performed after the required key authentication.

As described above, according to the present embodiment, the following effects can be obtained.
(6) Security can be improved by using the rolling code value of the vehicle 2 synchronized with the rolling code value of the portable device 3 for the alternative authentication when the second key authentication by the distance authentication is not established.

(7) In addition to being able to secure a backup means when distance authentication is not established, the security can be improved by a method rational for the user.
(8) In order to judge the validity of the backup means using the rolling code value synchronized in the process of the immediately preceding two-way communication, differentiate from the rolling code value in the past from the time of the last synchronization. Can be done. Therefore, it is possible to prevent theft method of illegally using the wireless signal eavesdropped in the past. In other words, the wireless unlock vulnerability can be eliminated.

It should be noted that the second embodiment can be modified and embodied as follows.
-The second key authentication combined with the first key authentication is not limited to distance authentication. For example, biometric authentication may be adopted as the second key authentication and combined with the first key authentication.

-Not only when unlocking, but also when starting the engine, it is possible to respond by adding the engine start function to the wireless function. In this case, the portable device 3 is provided with an engine start switch. Then, when the first key authentication is established and the second key authentication is not established, the engine is not started even if the in-vehicle switch instructing the engine start is pressed, so that the user can use the engine of the portable device 3. The engine will be started by wireless engine start (backup means) that turns on the start switch. Hereinafter, through the same action as in the case of unlocking, the same effect as in (6) to (8) according to the second embodiment is obtained.

-The alternative authentication of the second key authentication may be any method as long as it is an authentication using a common counter that can be synchronized between the vehicle 2 and the portable device 3 such as a rolling code value.
It should be noted that each of the above embodiments can be modified and embodied as follows.

-When updating the rolling code value of the portable device 3, instead of incrementing the rolling code value, the rolling code value may be created based on the date and time.

A configuration may be adopted in which the rolling code value of the portable device 3 is decremented each time the unlock switch 35 or the lock switch 36 is turned on. In this case, if the rolling code value of the portable device 3 is the same as the rolling code value of the vehicle 2 or the rolling code value of the portable device 3 is larger, the past wireless signal may have been eavesdropped. In addition to unlocking and locking, the synchronization process will not be performed.

-The device is not limited to vehicle 2. The present invention may be applied to a key authentication system for operating a building door, an electric appliance, or the like, provided that key authentication by wireless communication is established.

1 ... key authentication system, 2 ... vehicle (equipment), 3 ... portable device, 21 ... collation ECU (equipment control means), 22 ... LF transmitter, 23 ... UHF receiver, 24 ... touch sensor, 25 ... memory, 26 ... Lock button (outside switch), 27 ... Sensor, 31 ... Microcomputer (key control means), 32 ... LF reception circuit, 33 ... UHF transmission circuit, 34 ... Memory, 35 ... Unlock switch (switch), 36 ... Lock switch (switch).

Claims (3)

In a key authentication system that synchronizes rolling code values while performing key authentication by wireless communication between a device and a portable device.
The device includes device control means for transmitting a first radio signal requesting a rolling code value of the portable device.
The portable device includes a key control means for transmitting a second wireless signal including a rolling code value of the portable device in response to a request by the first wireless signal .
When the device control means acquires the key ID for which key authentication is established in connection with transmitting the request signal requesting the key ID of the portable device, the device control means transmits the first radio signal.
The device is a vehicle equipped with an external switch that indicates a door lock.
The device control means transmits the request signal to the outside of the vehicle when the outside switch is turned on.
The key authentication means is a key authentication system characterized in that it receives a request from the request signal and transmits a response signal including a key ID of the own portable device . In a key authentication system that synchronizes rolling code values while performing key authentication by wireless communication between a device and a portable device.
The device includes device control means for transmitting a first radio signal requesting a rolling code value of the portable device.
The portable device includes a key control means for transmitting a second wireless signal including a rolling code value of the portable device in response to a request by the first wireless signal.
When the device control means acquires the key ID for which key authentication is established in connection with transmitting the request signal requesting the key ID of the portable device, the device control means transmits the first radio signal.
The device is a vehicle equipped with a sensor that detects whether or not the vehicle is driving.
The device control means periodically transmits the request signal into the vehicle when the sensor detects that the vehicle is driving.
The key control means receives a request from the request signal and transmits a response signal including a key ID of the own portable device.
A key authentication system that features that . The device control means acquires the key ID for which the first key authentication of the key authentication is established and the first key authentication is established as a result of transmitting the request signal requesting the key ID of the portable device. However, when the second key authentication different from the first key authentication is not established, the rolling code value of the portable device included in the second radio signal is used for the alternative authentication of the second key authentication. The key authentication system according to claim 1 or 2 , wherein the rolling code value of the device synchronized with is used.