JP2011052412A - Electronic key system of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic key system of a vehicle, which is effective for the prevention of a forcible entry of a third person into a vehicle interior. <P>SOLUTION: In this electronic key system of the vehicle, a distance measurement signal Scd is given and received between an in-vehicle device 10 and a portable machine 20; it is determined through the giving and receiving of the signal that the portable machine 20 is positioned in a communicable area A; a request signal Srs and a response signal Sas are given and received; the authentication of the portable machine 20 is established through giving and receiving of the signals; and a vehicle door is unlocked on the basis of the determination and the establishment of the authentication. In this case, after a re-request signal Srr is transmitted after the transmission of the request signal Srs from the in-vehicle device 10, the portable machine 20 specifies a mode of a reply of the portable machine 20 to the re-request signal Srr. The vehicle door is unlocked under additional condition that the portable machine 20 replies to the re-request signal Srr on the basis of the specified reply mode. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electronic key system for a vehicle that performs various controls of the vehicle through wireless communication between the vehicle and a portable device.

  When the user holding the portable device (electronic key) approaches the vehicle door, the vehicle door is automatically unlocked, and when the user leaves the vehicle, the vehicle door is automatically locked. So-called electronic key systems are well known. Conventionally, as such an electronic key system, for example, a system described in Patent Document 1 is known. FIG. 11 shows an outline of an electronic key system that is generally employed in the past, including the system described in Patent Document 1.

  As shown in FIG. 11, in this electronic key system, the in-vehicle device 10 transmits a request signal to the communicable area A set around the vehicle door. In this electronic key system, the user has a portable device 20 that receives a request signal transmitted from the in-vehicle device 10 and transmits a response signal including an identification code (ID code) to the received request signal. . That is, when the user who has the portable device 20 enters the communicable area A, a response signal is transmitted from the portable device 20. In this system, the response signal transmitted from the portable device 20 is received by the in-vehicle device 10. In the in-vehicle device 10, the ID code of the portable device 20 included in the response signal is registered in advance in the in-vehicle device 10. The portable device 20 is authenticated by collating with the ID code. When the in-vehicle device 10 determines that the authentication of the portable device 20 has been established, the in-vehicle device 10 unlocks the vehicle door. On the other hand, in this system, for example, if the user who has the portable device 20 gets off the vehicle and then closes the door and then goes out of the communicable area A, the response signal is not transmitted from the portable device 20. Here, when the in-vehicle device 10 determines that the response signal cannot be received after transmitting the request signal, the in-vehicle device 10 locks the vehicle door.

  By the way, in such an electronic key system for a vehicle, wireless communication between the portable device 20 located outside the communicable area A and the in-vehicle device 10 is performed via a repeater. When a so-called relay attack that enables wireless communication is performed, the vehicle door may be unlocked illegally. If such a relay attack is performed by a third party, the vehicle door is unlocked in a situation where the user holding the portable device 20 is away from the vehicle, which is not preferable in terms of security.

  Therefore, in the electronic key system described in Patent Document 1, when the portable device 20 goes out of the communicable area A, a distance measurement signal is transmitted from the in-vehicle device 10 to the communicable area A. When the portable device 20 receives the distance measurement signal, it returns this signal to the in-vehicle device 10 as it is. Moreover, in this system, when the in-vehicle device 10 receives the distance measurement signal returned from the portable device 20, the in-vehicle device 10 calculates an elapsed time from transmission of the distance measurement signal to reception thereof, and based on the calculated elapsed time. The estimated distance from the vehicle to the portable device 20 is calculated. When the in-vehicle device 10 determines whether or not the portable device 20 is located in the communicable area A based on the calculated estimated distance, and determines that the portable device 20 is not located in the communicable area A The wireless communication with the portable device 20 is temporarily stopped. On the other hand, when the in-vehicle device 10 determines that the portable device 20 is located in the communicable area A based on the calculated distance, the in-vehicle device 10 transmits the above-described request signal and determines the ID code of the portable device 20. Collation is performed, and the vehicle door is unlocked based on the collation.

  According to such a configuration as an electronic key system of a vehicle, even if a third party performs a relay attack, in a situation where the portable device 20 is not located in the communicable area A, the in-vehicle device 10 and the portable device 20 Since the wireless communication between them is temporarily stopped, the vehicle door is kept locked. Therefore, illegal intrusion into the passenger compartment of a third party can be prevented and the security level of the vehicle as an electronic key system can be increased.

JP 2006-118886 A

  By the way, in such an electronic key system for a vehicle, in addition to the above-described repeater, a third party must prepare two types of repeaters that return the distance measurement signal transmitted from the in-vehicle device 10 as it is. If it is possible, a relay attack by a third party may be possible. More specifically, for example, the latter repeater is used when a distance measurement signal is transmitted from the in-vehicle device 10, and the former repeater is used when a request signal is transmitted from the in-vehicle device 10 thereafter. If used, there is a possibility that a relay attack by a third party becomes possible. Thus, in such an electronic key system, there is still room for improvement in that it is difficult to prevent unauthorized unlocking of the vehicle door when a relay attack higher than the above-described relay attack is performed. It has to be left.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a vehicle electronic key system that is effective in preventing illegal entry into a vehicle compartment by a third party.

  In order to solve the above problem, the invention according to claim 1 is a first reply mode in which a signal transmitted from an in-vehicle device to an area around the vehicle is returned as it is, and is transmitted from the in-vehicle device to the area. A portable device that can be set to any one of the second reply modes for returning a response signal including an identification code when receiving a request signal, and the portable device set to the first reply mode; A wireless signal is exchanged with the in-vehicle device, and it is determined that the portable device is located in the area through the signal exchange; and the portable device set in the second reply mode and On the condition that both the conditions that the request signal and the response signal are exchanged with the in-vehicle device and the authentication of the portable device is established through the signal exchange are satisfied. In the vehicle electronic key system that performs the unlocking of the vehicle, the in-vehicle device transmits a re-request signal after transmitting the request signal, and the request signal and the portable device are transmitted between the in-vehicle device and the portable device. In order to unlock the vehicle door by designating whether the portable device will reply in the first reply mode or the second reply mode in response to the re-request signal when sending / receiving a response signal The gist is that the condition further includes that the portable device makes a reply to the re-request signal based on the designated reply mode.

  According to this configuration, every time a request signal and a response signal are exchanged between the in-vehicle device and the portable device, the portable device sends a reply based on the first reply mode to the re-request signal, or A reply based on the second reply mode is made. For this reason, since it becomes difficult for a third party to specify the reply mode of the portable device for the re-request signal, even if the third party can prepare the two types of repeaters described above, the electronic device It becomes difficult to perform a relay attack on a key system. Therefore, if the vehicle door is unlocked on the condition that the portable device makes a reply based on the designated reply mode, a relay attack can be prevented, and a vehicle by a third party can be prevented. It becomes possible to prevent illegal intrusion into the room.

  According to a second aspect of the present invention, in the electronic key system for a vehicle according to the first aspect, the reply mode is designated by the portable device, and the portable device indicates the designated reply mode. Reply mode information is included in the response signal and transmitted to the in-vehicle device, and the in-vehicle device grasps the designated reply mode based on the reply mode information included in the response signal. Is the gist.

  In such an electronic key system for a vehicle, reply mode information indicating whether the portable device makes a reply in response to the re-request signal in the first or second reply mode is provided between the in-vehicle device and the portable device. Need to share between. In this regard, according to the above configuration, it is possible to share the reply mode information between the in-vehicle device and the portable device only by transmitting a response signal from the portable device to the in-vehicle device. The vehicle electronic key system according to claim 1 can be easily realized.

  According to a third aspect of the present invention, in the vehicle electronic key system according to the first or second aspect, the on-vehicle device transmits the re-request signal a plurality of times, and the portable device In response to a re-request signal transmitted a plurality of times from the in-vehicle device, a response is made a plurality of times in one of the first and second reply modes, and between the in-vehicle device and the portable device When the request signal and the response signal are transmitted / received, in which mode of the first reply mode and the second reply mode the portable device responds to each of the re-request signals transmitted a plurality of times. The gist is that it is specified.

  According to this configuration, every time a re-request signal is transmitted from the in-vehicle device a plurality of times, the portable device replies to the re-request signal based on the first reply mode, or a reply based on the second reply mode. Or to go. For this reason, since it becomes more difficult for a third party to specify the reply mode of the portable device for the re-request signal, it becomes very difficult for the third party to perform a relay attack on the electronic key system. Therefore, it becomes possible to prevent the relay attack more effectively, and it is possible to more appropriately prevent the illegal entry into the vehicle interior by a third party.

  According to the electronic key system for a vehicle according to the present invention, illegal intrusion into the vehicle interior by a third party can be prevented in advance.

The block diagram which shows the system configuration | structure about one Embodiment of the electronic key system of the vehicle concerning this invention. (A)-(d) is a timing chart which shows the operation example about the electronic key system of the vehicle of the embodiment. (A), (b) is a figure which shows typically the signal structure of the request signal transmitted from the vehicle-mounted apparatus about the electronic key system of the vehicle of the embodiment, and the figure which shows the authentication method of a portable device typically . The figure which shows typically the signal structure of the response signal transmitted from the portable device about the electronic key system of the vehicle of the embodiment. The flowchart which shows the process sequence about the process which unlocks the vehicle door by the vehicle-mounted apparatus about the electronic key system of the vehicle of the embodiment. Similarly, the flowchart which shows the process sequence about the process which unlocks the vehicle door by the vehicle-mounted apparatus about the electronic key system of the vehicle of the embodiment. The flowchart which shows the process sequence of the signal processing by the portable machine about the electronic key system of the vehicle of the embodiment. (A)-(d) is a timing chart which shows the other example of the operation | movement about the electronic key system of the vehicle of the embodiment. (A), (b) is the figure which shows typically the signal structure of the request signal transmitted from the vehicle-mounted apparatus about the electronic key system of the vehicle concerning this invention, and the other modification of the authentication method of a portable device FIG. The figure which shows typically the other modification of the signal structure of the response signal transmitted from the portable machine about the electronic key system of the vehicle concerning this invention. The top view which shows typically the outline | summary of the electronic key system generally employ | adopted conventionally.

  Hereinafter, an embodiment of an electronic key system for a vehicle according to the present invention will be described with reference to FIGS. The basic configuration of the electronic key system to which this embodiment is applied is the same as that of the electronic key system illustrated in FIG. FIG. 1 is a block diagram showing the system configuration of such an electronic key system. First, the configuration of this electronic key system will be described with reference to FIG.

  As shown in FIG. 1, in this electronic key system, various types of communication control by wireless communication are executed between an in-vehicle device 10 mounted on the vehicle side and a portable device 20 carried by the user.

  Here, the in-vehicle device 10 includes a receiving device 12 that receives a radio signal transmitted from the portable device 20 together with a transmitting device 11 that transmits a radio signal to the communicable area A set around the vehicle door. It has been. Incidentally, the radio signal transmitted from the transmitter 11 includes, for example, the switching element off signal Sds and the re-request signal Srr in addition to the distance measurement signal Scd and the request signal Srs described above. On the other hand, the radio signal received by the receiving device 12 includes, for example, the re-response signal Sar in addition to the distance measurement signal Scd and the response signal Sas described above. Then, transmission control of various wireless signals by the transmission device 11 and processing of various wireless signals received through the reception device 12 are performed in an integrated manner through the vehicle control device 13 that is also provided in the in-vehicle device 10. The vehicle control device 13 is also a part that controls the lock / unlock operation of the vehicle door through a door lock mechanism 14 provided on the vehicle door.

  On the other hand, the portable device 20 receives wireless signals such as the distance measurement signal Scd and response signal Sas together with the receiving device 21 that receives the wireless signals such as the distance measurement signal Scd and the request signal Srs transmitted from the in-vehicle device 10. A transmission device 22 for transmission is provided. Then, the generation of the response signal Sas and the reresponse signal Sar based on the reception of the request signal Srs and the rerequest signal Srr, and the transmission control of the response signal Sas and the reresponse signal Sar through the transmission device 22 are also performed on the portable device 20. It is performed in an integrated manner through the portable device control device 23 provided. The portable device 20 is provided with a signal transmission path 24 for transmitting the signal received by the receiving apparatus 21 to the transmitting apparatus 22 as it is, and a switching element 25 for intermittently connecting the path 24. In the portable device 20, the on / off control of the switching element 25 is performed through the portable device control device 23.

  In the electronic key system configured as described above, when the distance measurement signal Scd is issued from the transmission device 11 to the communicable area A, the portable device 20 possessed by the user is in the communicable area. Assuming that the vehicle has entered A, signals are exchanged between the in-vehicle device 10 and the portable device 20 in the manner shown in FIG. 2C and 2D, it is assumed that the switching element 25 is turned on as an initial state and the vehicle door is locked as an initial state.

  First, the vehicle control device 13 generates the distance measurement signal Scd, and transmits the generated distance measurement signal Scd to the communicable area A via the transmission device 11. In addition, when the vehicle control device 13 transmits the distance measurement signal Scd as described above, the vehicle control device 13 measures the delay time from the time when the distance measurement signal Scd is transmitted by the built-in timer. Here, as shown in FIG. 2A, if the distance measurement signal Scd is issued from the transmission device 11 to the communicable area A at the time t1, the distance measurement signal Scd is transmitted to the reception device 21. Received by. As a result, the distance measurement signal Scd is transmitted to the transmission device 22 via the signal transmission path 24, and is directly returned from the transmission device 22 to the in-vehicle device 10 as shown in FIG. 2B (time t2). ). When the distance measurement signal Scd is returned in this manner, the vehicle control device 13 receives this via the reception device 12 and stops measuring the timer when the distance measurement signal Scd is received. Then, the vehicle control device 13 calculates a delay time from when the distance measurement signal Scd is transmitted until it is received, that is, a time Ta from time t1 to time t2, based on the measured value of the timer. By the way, there is a correlation between the calculated delay time Ta and the distance from the vehicle to the portable device 20 such that the longer the distance from the vehicle to the portable device 20, the longer the delay time Ta. Therefore, in the present embodiment, a map indicating the relationship between the estimated distance from the vehicle to the portable device 20 and the delay time Ta is stored in the memory of the vehicle control device 13 in advance, and the vehicle is determined based on the calculated delay time Ta. The map calculates the estimated distance from the mobile device 20 to the mobile device 20.

  When the vehicle control device 13 determines that the estimated distance from the vehicle to the portable device 20 is within a predetermined distance, the vehicle control device 13 determines that the portable device 20 is located in the communicable area A, and FIG. As shown in FIG. 4, the switching element off signal Sds is generated and transmitted to the communicable area A via the transmitter 11 (time t3). Then, when the portable device control device 23 receives the transmitted switching element off signal Sds via the receiving device 21, the switching device 25 is turned off as shown in FIG.

  Thereafter, as shown in FIG. 2A, the vehicle control device 13 generates a request signal Srs and transmits it to the communicable area A via the transmission device 11 (time t4). Then, the portable device control device 23 receives the transmitted request signal Srs via the reception device 21 and generates a response signal Sas based on the reception of the request signal Srs. Then, as shown in FIG. 2B, the portable device control device 23 transmits the generated response signal Sas to the in-vehicle device 10 via the transmission device 22 (time t5). By transmitting the response signal Sas in this way, the vehicle control device 13 receives the response signal Sas via the receiving device 12, and authenticates the portable device 20 based on information included in the response signal Sas. I do. Incidentally, in this embodiment, in order to increase the security level of the electronic key system, a so-called challenge response authentication method is adopted as the authentication method of the portable device 20. Here, the challenge response authentication method is based on the result of having a common encryption key between the in-vehicle device 10 and the portable device 20 and encrypting random number information (challenge code) with each encryption key. Is to do.

  By the way, in such an electronic key system, when the vehicle door is unlocked on the condition that authentication of the portable device 20 is established, a repeater that returns a signal transmitted from the in-vehicle device 10 as it is, and the in-vehicle device 10 There is a possibility that the above-described relay attack may be possible by preparing two types of repeaters, ie, repeaters that relay wireless communication between the mobile device 20 and the portable device 20. That is, when the distance measurement signal Scd is exchanged between the in-vehicle device 10 and the portable device 20, the former repeater is used, and the switching element off signal Sds between the in-vehicle device 10 and the portable device 20 is used. If the latter repeater is used when sending / receiving the request signal Srs and the response signal Sas, there is a possibility that a relay attack may be possible. If a third party performs such a relay attack, the vehicle door may be unlocked illegally in a situation where the portable device 20 possessed by the user is located outside the communicable area A.

  Therefore, in the present embodiment, as shown in FIG. 2, after the authentication of the portable device 20 is established, the re-request signal Srr is transmitted from the in-vehicle device 10, and the portable device 20 that has received the re-request signal Srr is The reply is made in either the first reply mode in which the signal Srr is sent back as it is or the second reply mode in which the reply signal Sas is sent back. By the way, in this electronic key system, when the request signal Srs and the response signal Sas are exchanged between the in-vehicle device 10 and the portable device 20, the reply mode of the portable device 20 is designated on the portable device 20 side. The portable device 20 notifies the in-vehicle device 10 of information (reply mode information) designated by itself. Then, the vehicle control device 13 determines whether or not the portable device 20 makes a reply based on the reply mode information with respect to the re-request signal Srr, and the portable device 20 makes a reply based on the reply mode information. When it is determined, the vehicle door is unlocked.

  Next, with reference to FIGS. 3 and 4, a method in which the portable device 20 notifies the in-vehicle device 10 of the reply mode information will be specifically described. Here, for the sake of convenience, an overview of challenge response authentication will also be described. Further, it is assumed that the common encryption key K described above is stored in the memory of the vehicle control device 13 and the memory of the portable device 20.

  As shown in FIG. 3A, the vehicle control device 13 randomly generates the challenge code described above and transmits a request signal Srs including the challenge code to the communicable area A.

  On the other hand, as shown in FIG. 4, when the portable device control device 23 receives the request signal Srs, the portable device control device 23 determines in which of the first and second reply modes the reply is made to the re-request signal Srr. A reply mode code in which the information is coded and the information is encoded is generated. The portable device control device 23 generates a single code by combining the challenge code and the reply mode code included in the request signal Srs, and uses the generated code to store the encryption key K stored in the built-in memory. An encryption code is generated by using the encryption. Furthermore, the portable device control device 23 generates a response signal Sas including an encryption code and transmits it to the in-vehicle device 10. Thus, if the challenge code and the reply mode code are combined and encrypted as a whole, if the value of the challenge code changes, the value of the encrypted code changes. Even if it is done, it becomes difficult for a third party to know the contents of the reply mode code. For this reason, a security level can be raised now.

  On the other hand, as shown in FIG. 3 (b), when the vehicle control device 13 receives the response signal Sas, it decrypts the response signal Sas using the encryption key K stored in the built-in memory. The challenge code and the reply mode code are extracted. Then, the vehicle control device 13 collates the challenge code generated by itself shown in FIG. 3A and the challenge code included in the response signal Sas. If it is determined that the mobile device 20 is authenticated, it is determined that the authentication of the portable device 20 has been established. Further, when the vehicle control device 13 determines that the authentication of the portable device 20 is established, the vehicle control device 13 starts transmitting the re-request signal Srr. Incidentally, the vehicle control device 13 recognizes in which mode the portable device 20 performs a reply in the first reply mode or the second reply mode based on the reply mode code extracted from the response signal Sas.

When the re-request signal Srr is transmitted from the in-vehicle device 10 in this way, signals are exchanged between the in-vehicle device 10 and the portable device 20 in the following manner.
That is, for example, assume that the reply mode designated by the portable device control device 23 is the first reply mode. At this time, as shown in FIG. 2C, the portable device control device 23 turns on the switching element 25 when the transmission of the response signal Sas is completed (time t5). Therefore, as shown in FIG. 2B, when the re-request signal Srr is transmitted from the in-vehicle device 10 at time t6, the portable device is operated in the same manner as the above-described manner of sending and receiving the distance measurement signal Scd. 20, the re-request signal Srr is returned as it is. Therefore, as indicated by a solid line in FIG. 2B, the delay time from the time when the transmission of the re-request signal Srr is completed until the time when the reception of the re-request signal Srr is completed is from time t6 in the figure. Time Ts1 until time t7 is reached. Incidentally, the portable device control device 23 turns off the switching element 25 when a predetermined time Tb elapses from the time t5 when the switching element 25 is turned on (time t8).

  On the other hand, for example, assume that the reply mode designated by the portable device control device 23 is the second reply mode. At this time, as indicated by a two-dot chain line in FIG. 2C, the portable device control device 23 maintains the switching element 25 in the OFF state. For this reason, as shown in FIG. 2B, when the re-request signal Srr is transmitted from the in-vehicle device 10, the portable device 20 is operated in a manner similar to the manner of sending and receiving the request signal Srs and the response signal Sas. Transmits a re-response signal Sar. Incidentally, the re-response signal Sar has a signal configuration obtained by removing the reply mode code from the response signal Sas. At this time, the delay time from the completion of transmission of the re-request signal Srr to the completion of reception of the re-response signal Sar is a time Ts2 from time t6 to time t7 ′ in the figure, that is, the delay time Ts1. It will be a longer time.

  Therefore, in this embodiment, the vehicle control device 13 measures the delay time Ts from the completion of the transmission of the re-request signal Srr to the completion of the reception of the signal transmitted from the portable device 20 by the built-in timer. Based on the comparison between the measured delay time Ts and the predetermined time Tc, the following determinations (a1) and (a2) are performed. Incidentally, the predetermined time Tc is set in advance by experiments or the like so as to be longer than the delay time Ts1 and shorter than the delay time Ts2.

(A1) When it is determined that the measured delay time Ts is equal to or shorter than the predetermined time Tc. At this time, it is determined that the reply mode of the portable device 20 is the first reply mode.
(A2) When it is determined that the measured delay time Ts is longer than the predetermined time Tc. At this time, it is determined that the reply mode of the portable device 20 is the second reply mode.

  When the vehicle control device 13 determines that the return mode of the portable device 20 is the first return mode based on the return mode code included in the response signal Sas, for example, the determination result of (a1) Is obtained, it is determined that the legitimate portable device 20 is sending a reply, and the vehicle door is unlocked through the door lock mechanism 14 as shown in FIG. 2 (d) (time t7). On the other hand, if it is determined that the reply mode of the portable device 20 is the first reply mode, if the determination result of (a2) is obtained, it is determined that there is a possibility that a relay attack is being performed. , Keep the vehicle door locked.

  FIGS. 5 to 7 show processes executed through the vehicle control device 13 and the portable device control device 23 when unlocking the vehicle door, and are based on FIGS. 5 to 7 below. The specific procedures for these processes are summarized.

  As shown in FIG. 5, in the process executed through the vehicle control device 13, first, the distance measurement signal Scd is transmitted to the communicable area A (step 10), and the distance returned from the portable device 20 as it is. It is determined whether or not the measurement signal Scd has been received (step S11). When it is determined that the distance measurement signal Scd has been received (step S11: YES), as described above, from the vehicle based on the delay time Ta from when the distance measurement signal Scd is transmitted until it is received. An estimated distance to the portable device 20 is calculated (step S12), and it is determined whether the portable device 20 is located in the communicable area A based on the calculated estimated distance (step S13). When it is determined that the portable device 20 is not located in the communicable area A (step S13: NO), communication with the portable device 20 is temporarily stopped (step S14). That is, in this process, when it is determined that the portable device 20 is not located in the communicable area A, there is a possibility that the portable device 20 located outside the communicable area A is performing communication. It is determined that there is a possibility that a relay attack is being performed, and the communication with the portable device 20 is temporarily stopped to prevent the relay attack.

  On the other hand, when it is determined that the portable device is located in the communicable area A (step S13: YES), the switching element off signal Sds is transmitted to the communicable area A (step S15), and thereafter The request signal Srs is transmitted to the communicable area A (step S16). Subsequently, it is determined whether or not the response signal Sas has been received from when the request signal Srs is transmitted until a predetermined time elapses (step S17), and it is determined that the response signal Sas has been received. (Step S17: YES), the portable device 20 is authenticated based on the above-described challenge response authentication (Step S18). Then, it is determined whether or not the authentication of the portable device 20 has been established (step S19), and when it is determined that the authentication of the portable device 20 has been established (step S19: YES), as shown in FIG. The reply mode information is extracted from the reply mode code included in the response signal Sas (step S20), and the re-request signal Srr is transmitted to the communicable area A (step S21). Also, when the transmission of the re-request signal Srr is completed through the process of step S21, the timer starts counting up (step S22), and the predetermined time elapses from the time when the re-request signal Srr is transmitted. It is determined whether or not a signal returned from the portable device 20 has been received (step S23). If the signal returned from the portable device 20 cannot be received before the predetermined time has elapsed (step S23: NO), the timer count-up is stopped (step S24), and the vehicle The control device 13 ends this series of processing.

  On the other hand, when the signal returned from the portable device 20 can be received before the predetermined time elapses (step S23: YES), the timer count-up is stopped (step S25). Subsequently, based on the measured value of the timer, a delay time Ts from the time when transmission of the re-request signal Srr is completed to the time when reception of the signal returned from the portable device 20 is completed is calculated (step S26). ) Based on the calculated delay time Ts, the reply mode of the portable device 20 is determined by performing the determination shown in (a1) and (a2) described above (step S27). When it is determined whether or not the determined reply mode of the portable device 20 matches the reply mode information extracted in the process of step S19 (step S28), it is determined that they match each other. (Step S28: YES), the vehicle door is unlocked (step S29), and the vehicle control device 13 ends this series of processes. On the other hand, when it is determined that they do not match each other (step S28: NO), the vehicle control device 13 ends this series of processes without unlocking the vehicle door.

  On the other hand, as shown in FIG. 7, in the process executed by the portable device control device 23, first, it is determined whether or not the switching element off signal Sds has been received (step S30), and the switching element off signal Sds. Is determined (step S30: YES), the switching element 25 is turned off (step S31). Thereafter, it is determined whether or not the request signal Srs has been received before a predetermined time has elapsed since the switching element OFF signal Sds was received (step S32), and when it is determined that the request signal Srs has been received. (Step S32: YES), it is determined at random whether the reply is made in the first or second reply mode in response to the re-request signal Srr (step S33). Subsequently, a reply mode code is generated based on the determined reply mode (step S34), and a response signal Sas is generated based on the generated reply mode code and the challenge code included in the response signal Sas. (Step S35), this is transmitted to the in-vehicle device 10 (Step S36).

  Then, following the processing in step S36, it is determined whether or not the reply mode determined in step S33 is the first reply mode (step S37), and it is determined that the reply mode is the first reply mode. In that case (step S37: YES), the switching element 25 is turned on (step S38). Further, in the subsequent step S39, it is determined whether or not the predetermined time Tb has elapsed since the switching element 25 was turned on. Specifically, the elapsed time from when the switching element 25 is turned on is measured through a timer built in the portable device control device 23, and the elapsed time is equal to or longer than the predetermined time Tb. Thus, it is determined that the predetermined time Tb has elapsed since the switching element 25 was turned on. When it is determined that the predetermined time Tb has elapsed since the switching element 25 is turned on (step S39: YES), the switching element 25 is turned off (step S40), and the portable device control device 23 is turned on. Terminates this series of processing.

  On the other hand, if it is determined through the process of step S37 that the reply mode determined in step S33 is not the first reply mode (step S37: NO), that is, it is determined that the reply mode is the second reply mode. If the response signal Sas has been received, it is determined whether or not the re-request signal Srr has been received before a predetermined time has elapsed since the response signal Sas was transmitted (step S41). When it is determined that the re-request signal Srr has been received (step S41: YES), the re-response signal Sar is transmitted to the in-vehicle device 10 (step S42), and the portable device control device 23 performs this series. Terminate the process.

  According to such a configuration as the electronic key system, every time the request signal Srs and the response signal Sas are exchanged between the in-vehicle device 10 and the portable device 20, the portable device 20 receives the first request signal Srr for the first request signal Srr. Or a reply based on the second reply mode or a reply based on the second reply mode. For this reason, since it becomes difficult for a third party to specify the reply mode of the portable device 20 for the re-request signal Srr, even if the third party can prepare the two types of repeaters described above, It is difficult to perform a relay attack on the electronic key system. Accordingly, if the vehicle door 20 is unlocked on the condition that the mobile device 20 makes a reply based on the reply mode designated by the mobile device 20, a relay attack can be prevented. As a result, illegal intrusion into the vehicle interior by a third party can be prevented in advance.

As described above, according to the electronic key system for a vehicle according to the present embodiment, the following effects can be obtained.
(1) When the request signal Srs is transmitted from the in-vehicle device 10 and then the re-request signal Srr is transmitted, and when the request signal Srs and the response signal Sas are exchanged between the in-vehicle device 10 and the portable device 20. The portable device 20 specifies whether the portable device 20 makes a reply in response to the re-request signal Srr in the first or second reply mode. The in-vehicle device 10 unlocks the vehicle door on the condition that the portable device 20 makes a reply to the re-request signal Srr based on the designated reply mode. As a result, it becomes difficult for a third party to specify the reply mode of the portable device 20 for the re-request signal Srr, so that it is possible to prevent a relay attack, and thus an illegal entry into the vehicle interior by the third party is obviated. Will be able to prevent.

  (2) The challenge response authentication method is adopted as the authentication method of the portable device 20. Thereby, the security level as a system can be raised.

  (3) By including reply mode information indicating the reply mode designated by the portable device 20 in the response signal Sas and transmitting it from the portable device 20 to the in-vehicle device 10, the in-vehicle device 10 can grasp the reply mode designated by the portable device. I did it. Thereby, it becomes possible to share the reply mode information between the in-vehicle device 10 and the portable device 20 only by transmitting the response signal Sas from the portable device 20 to the in-vehicle device 10.

  (4) A single code is generated by combining the challenge code and the reply mode code, and the generated code is encrypted to generate an encrypted code, and the encrypted code is included in the response signal and transmitted. did. As a result, the value of the encryption code changes with the change in the value of the challenge code, so that even if the encryption code is intercepted by a third party, the third party can know the contents of the reply mode code. It becomes difficult. For this reason, a security level can be raised now.

In addition, the said embodiment can also be implemented with the following forms which changed this suitably.
In the above-described embodiment, the portable device 20 designates whether to reply in the first or second reply mode with respect to the re-request signal Srr. In addition to this, for example, the delay time from when the in-vehicle device 10 transmits the re-request signal Srr to the reception of the re-response signal Sar, that is, the delay time Ts2 shown in FIG. . Incidentally, as a method for designating the delay time Ts2, for example, there is a method in which the portable device control device 23 designates a delay time from when the re-request signal Srr is received until the re-response signal Sar is transmitted. If such a method is adopted, this delay time information is included in the response signal Sas together with the reply mode information, and is transmitted from the portable device 20 to the in-vehicle device 10, so that the delay time designated by the portable device control device 23. Can be grasped by the vehicle control device 13. The vehicle control device 13 measures the delay time from when the re-request signal Srr is transmitted until the re-response signal Sar is received by the built-in timer, and the measured delay time is the specified delay time. The vehicle door is unlocked based on the further determination that there is. According to such a configuration, every time the request signal Srs and the response signal Sas are exchanged between the in-vehicle device 10 and the portable device 20, the delay time becomes shorter or longer. It is very difficult for a third party to perform a relay attack that reflects the length of the delay time. Therefore, it becomes possible to effectively prevent relay attack, so that it is possible to suitably prevent illegal entry into the vehicle interior by a third party.

  The in-vehicle device 10 transmits the re-request signal Srr a plurality of times, and the portable device 20 has a plurality of the re-request signal Srr transmitted a plurality of times in any one of the first and second reply modes. A reply may be made once. In this case, it may be specified whether the portable device 20 performs a reply in one of the first and second reply modes for each of the re-request signals Srr transmitted a plurality of times. Specifically, as shown in FIG. 8, for example, if the in-vehicle device 10 is configured to transmit two re-request signals Srr1, Srr2, the portable device control device 23 responds to the first re-request signal Srr1. The reply mode is determined in such a manner that a reply is made in the first reply mode and a reply is made in the second reply mode to the next re-request signal Srr2. In the vehicle control device 13, the portable device 20 makes a reply in the first reply mode to the first re-request signal Srr1, and the portable device in the second reply mode to the next re-request signal Srr2. When it is determined that 20 has made a reply, that is, at time t9 in the drawing, the vehicle door is unlocked. Needless to say, the portable device may reply in response to the two re-request signals Srr1, Srr2.

  In the above embodiment, the mobile device 20 is authenticated based on the method illustrated in FIGS. 3 and 4, but instead, for example, based on the method illustrated in FIGS. 9 and 10. Authentication of the portable device 20 may be performed. That is, as shown in FIG. 10 as a diagram corresponding to FIG. 4, the portable device 20 generates an encryption code by the same method as the method illustrated in FIG. The response signal Sas including the unit is generated and transmitted to the in-vehicle device 10. On the other hand, as shown in FIG. 9 as a diagram corresponding to the previous FIG. 3, the vehicle control device 13 generates a single code by combining the challenge code generated by itself and the code indicating the first reply mode, A first encryption code is generated by encrypting the generated code using the encryption key K. Further, the vehicle control device 13 generates a single code by combining the challenge code and the code indicating the second reply mode, and encrypts the generated code by using the encryption key K to generate the second encryption. Generates the code. Then, the vehicle control device 13 extracts a part of each of the generated first and second encrypted codes, and collates each part with a part of the encrypted code included in the response signal Sas. Then, when it is determined that a part of the encryption code included in the response signal matches the part of the first encryption code, or a part of the encryption code included in the response signal is the second When it is determined that it matches a part of the encrypted code, it is determined that authentication of the portable device 20 has been established. For example, when the vehicle control device 13 determines that a part of the encrypted code included in the response signal matches a part of the first encrypted code, the portable device 20 uses the first reply mode. Understand that you will reply. By adopting such a method as the authentication method of the portable device 20, even if the portable device 20 cannot transmit all the encryption codes due to the limitation of the number of transmission bits, the encryption is performed on the portable device 20 side. Even when the converted code cannot be decrypted on the vehicle control device 13 side, the vehicle control device 13 can authenticate the portable device 20 and grasp the reply mode of the portable device 20.

In the above embodiment, authentication of the portable device 20 is performed based on challenge response authentication. However, other authentication methods can be appropriately employed.
In the above embodiment, the portable device 20 designates in which mode the first or second reply mode is replied to the re-request signal Srr on the portable device 20 side. Instead, it may be specified on the in-vehicle device 10 side. In this case, if the reply mode information indicating the reply mode designated by the in-vehicle device 10 is included in the request signal Srs and transmitted to the portable device 20, the reply mode information between the in-vehicle device and the portable device is indicated. Sharing becomes possible.
(Appendix)
Next, a technical idea that can be grasped from the above embodiment and its modifications will be additionally described.

  (A) The vehicle electronic key system according to any one of claims 1 to 3, wherein the authentication of the portable device is authentication based on challenge response authentication. Specifically, if the authentication method based on the challenge response method is adopted as the portable device authentication method as in the same configuration, the security level as the system can be increased.

  (B) In the electronic key system for a vehicle described in Appendix A, the portable device generates a single code by combining a challenge code used for the challenge response authentication and a return mode code indicating the return mode information. An electronic key system for a vehicle, wherein the generated code is encrypted to generate an encrypted code, and the encrypted code is included in the response signal and transmitted to the in-vehicle device. According to this configuration, since the value of the encryption code changes with the change in the value of the challenge code, even if the encryption code is intercepted by a third party, the third party It becomes difficult to know. For this reason, the security level can be further increased.

  (C) In the electronic key system for a vehicle according to any one of claims 1 to 3, appendix i, and appendix b, from when the in-vehicle device transmits the re-request signal until the response signal is received. Measuring means for measuring the delay time, and when the request signal and the response signal are exchanged between the in-vehicle device and the portable device, the response is made after the in-vehicle device transmits the re-request signal. A delay time until receiving a signal is further specified, and the condition for unlocking the vehicle door further includes the delay time measured through the measuring means being the specified delay time. The vehicle's electronic key system. According to this configuration, every time a request signal and a response signal are exchanged between the in-vehicle device and the portable device, the delay time from when the in-vehicle device transmits a re-request signal to when the response signal is received is short. It becomes very difficult for a third party to perform a relay attack that reflects the length of the delay time. Therefore, after the delay time is measured through the measuring means, the vehicle door is unlocked on condition that the delay time detected through the measuring means is the specified delay time. A relay attack can be effectively prevented, and an illegal intrusion by a third party into the vehicle interior can be suitably prevented.

  A ... Communicable area, Sar ... Re-response signal, Sas ... Response signal, Scd ... Distance measurement signal, Sds ... Switching element off signal, Srr ... Re-request signal, Srs ... Request signal, 10 ... In-vehicle device, 11 ... Transmission device , 12 ... receiving device, 13 ... vehicle control device, 14 ... door lock mechanism, 20 ... portable device, 21 ... receiving device, 22 ... transmitting device, 23 ... portable device control device, 24 ... signal transmission path, 25 ... switching element .

Claims (3)

A first reply mode for returning a signal transmitted from the in-vehicle device to the area around the vehicle as it is, and a response signal including an identification code when receiving a request signal transmitted from the in-vehicle device to the area. A portable device that can be set to any one of the two reply modes, and exchanges radio signals between the portable device set to the first reply mode and the in-vehicle device, and through this signal exchange It is determined that the portable device is located in the area, and the request signal and the response signal are exchanged between the portable device set in the second reply mode and the in-vehicle device. In an electronic key system for a vehicle that unlocks a vehicle door on the condition that both conditions that the authentication of the portable device is established through lever signal exchange are satisfied
The in-vehicle device transmits a re-request signal after transmitting the request signal, and when the request signal and the response signal are exchanged between the in-vehicle device and the portable device, the re-request signal In which of the first and second reply modes the mobile device sends a reply, and the condition for unlocking the vehicle door is designated for the re-request signal. The vehicle electronic key system further comprising: the portable device performing a reply based on the reply mode. The reply mode is designated by the portable device, and the portable device includes reply mode information indicating the designated reply mode in the response signal and transmits the reply signal to the in-vehicle device. The vehicle electronic key system according to claim 1, wherein the device grasps the designated reply mode based on reply mode information included in the response signal. The in-vehicle device performs transmission of the re-request signal a plurality of times, and the portable device performs the first and second reply modes in response to the re-request signal transmitted from the in-vehicle device a plurality of times. Each of the re-request signals that are replied a plurality of times in any mode, each of the re-request signals transmitted a plurality of times when the request signal and the response signal are exchanged between the in-vehicle device and the portable device 3. The vehicle electronic key system according to claim 1, wherein the portable device designates in which of the first and second reply modes a reply is made.

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