JP7578011B2 - Electronic information storage medium, key sharing method, and program - Google Patents

Description

The present invention relates to technologies such as systems and methods that use keys (digital keys) to control controlled objects such as vehicles.

Conventionally, a system is known in which a key is used from a mobile terminal such as a smartphone to start a vehicle engine or unlock the doors. For example, in Patent Document 1, a digital key for accessing the vehicle is stored in the vehicle, and when a proximity condition between the mobile computing device and the vehicle is satisfied, communication based on the digital key is performed.

Special table 2017-509171 publication

The above-mentioned keys need to be stored in a secure element (SE) installed in the vehicle, but since a vehicle has multiple doors, it is desirable to store and manage the keys for unlocking each of the multiple doors (i.e., the keys for unlocking the doors) in separate SEs. It is also desirable to store and manage the key for starting the engine in a different SE from the key for unlocking the doors. If each of the above-mentioned keys were stored and managed in a single SE, processing would be concentrated in that SE, which could cause processing delays. Furthermore, if that SE breaks down, it could become difficult to unlock each door and start the engine. However, since the same keys need to be stored in each SE, a mechanism for sharing these keys is required.

The present invention has been made in consideration of the above points, and aims to provide an electronic information storage medium, a key sharing method, and a program that enable efficient key sharing among controlled objects such as vehicles.

In order to solve the above problem, the invention described in claim 1 is a system in which each of a plurality of electronic information storage media mounted on a controlled object can write a key used to control each of a plurality of facilities within the controlled object into its respective memory, characterized in that the first electronic information storage medium communicates with a device outside the controlled object among the plurality of electronic information storage media, the first electronic information storage medium comprising a writing means for writing a key obtained by performing key pairing with the device into memory, a mutual authentication means for performing mutual authentication with a second electronic information storage medium among the plurality of electronic information storage media, and a transmitting means for transmitting the obtained key and a command to write the key into memory to the second electronic information storage medium through a secure session established by the mutual authentication.

The invention described in claim 2 is characterized in that, in the first electronic information storage medium described in claim 1, when the key and a command to write the key to memory are transmitted to the second electronic information storage medium, the writing means writes data indicating that the key has been transmitted to the memory in association with the key.

The invention described in claim 3 is characterized in that, in the first electronic information storage medium described in claim 2, when there are multiple second electronic information storage media among the multiple electronic information storage media, the writing means writes data that can distinguish whether the key has been transmitted or not for each second electronic information storage medium to the memory in correspondence with the key.

The invention described in claim 4 is characterized in that, in the first electronic information storage medium described in any one of claims 1 to 3, the first electronic information storage medium is capable of wireless communication with a plurality of devices, the writing means writes each key obtained by performing key pairing with each of the plurality of devices into a memory distinguished for each of the devices, and the transmission means transmits each key obtained by performing key pairing with each of the plurality of devices and a command to write each key into a memory to the second electronic information storage medium through a secure session established by the mutual authentication.

The invention described in claim 5 is characterized in that, in the first electronic information storage medium described in claim 4, when the key and a command to write the key to memory are transmitted to the second electronic information storage medium, the writing means writes data indicating that the key has been transmitted to the memory in correspondence with the key, distinguishing it for each device.

The invention described in claim 6 is a key sharing method in a system in which each of a plurality of electronic information storage media mounted on a controlled object can write a key used to control each of a plurality of facilities in the controlled object into its respective memory, and is characterized by including a step in which a first electronic information storage medium, which communicates with a device outside the controlled object among the plurality of electronic information storage media, writes a key obtained by performing key pairing with the device into its memory; a step in which the first electronic information storage medium performs mutual authentication with a second electronic information storage medium among the plurality of electronic information storage media; a step in which the first electronic information storage medium transmits the obtained key and a command to write the key into its memory to the second electronic information storage medium through a secure session established by the mutual authentication; and a step in which the second electronic information storage medium writes the key into its memory in response to the command from the first electronic information storage medium.

The invention described in claim 7 is characterized in that, in the key sharing method described in claim 6, the method further includes a step of, when the first electronic information storage medium is inoperable, writing to memory a key obtained by the second electronic information storage medium executing key pairing with the device on behalf of the first electronic information storage medium, and a step of the device notifying a user of the device that the key pairing has been performed on behalf of the second electronic information storage medium.

The invention described in claim 8 is characterized in that, in the key sharing method described in claim 6 or 7, when the first electronic information storage medium is replaced with a third electronic information storage medium other than the plurality of electronic information storage media after the key has been written to the memory of each of the first electronic information storage medium and the second electronic information storage medium, the invention further includes a step of the second electronic information storage medium performing mutual authentication with the third electronic information storage medium, a step of the second electronic information storage medium transmitting the written key and a command to write the key to the memory to the third electronic information storage medium through a secure session established by the mutual authentication, and a step of the third electronic information storage medium writing the key to the memory in response to the command from the second electronic information storage medium.

The invention described in claim 9 is characterized in that, in the key sharing method described in claim 6 or 7, when the first electronic information storage medium is replaced with a third electronic information storage medium other than the plurality of electronic information storage media after the key is written in the memory of each of the first electronic information storage medium and the second electronic information storage medium, the third electronic information storage medium executes mutual authentication with the second electronic information storage medium, the third electronic information storage medium transmits a command to transmit the key to the second electronic information storage medium through a secure session established by the mutual authentication, the second electronic information storage medium acquires the key from the memory in response to the command from the third electronic information storage medium and transmits the acquired key to the third electronic information storage medium through the secure session established by the mutual authentication, and the third electronic information storage medium writes the key from the second electronic information storage medium to its memory.

The invention described in claim 10 is characterized in that in a system in which each of a plurality of electronic information storage media mounted on a controlled object can write a key used to control each of a plurality of facilities within the controlled object into its respective memory, the computer included in a first electronic information storage medium among the plurality of electronic information storage media that communicates with a device outside the controlled object is made to function as a writing means for writing a key obtained by performing key pairing with the device into memory, a mutual authentication means for performing mutual authentication with a second electronic information storage medium among the plurality of electronic information storage media, and a transmitting means for transmitting the obtained key and a command to write the key into memory to the second electronic information storage medium through a secure session established by the mutual authentication.

The present invention makes it possible to efficiently share keys among controlled objects such as vehicles.

1 is a diagram showing an example of a schematic configuration of a communication system S according to an embodiment of the present invention; FIG. 2 is a diagram illustrating an example of a schematic configuration of a device 1. FIG. 2 is a diagram illustrating an example of a schematic configuration of an ECU 2. A diagram showing an example of the general configuration of a parent eSE3a and a child eSE3b. A diagram showing an example of the connection state between parent eSE3a and child eSE3b. (A) is a diagram showing an example in which a common key obtained by pairing with device 1-1, its key ID, and a child eSE distribution flag are associated and stored, and (B) is a diagram showing an example in which a common key obtained by pairing with device 1-2, its key ID, and a child eSE distribution flag are associated and stored. 13A is a flowchart showing an example of pairing processing performed by the CPU 35 in the parent eSE 3a, and FIG. 13B is a flowchart showing an example of mutual authentication processing performed by the CPU 35 in the parent eSE 3a. FIG. 11 is a sequence diagram showing details of the mutual authentication in step S13.

Below, an embodiment of the present invention will be described in detail with reference to the drawings. The embodiment described below is an embodiment in which the present invention is applied to a communication system equipped with multiple eSEs (embedded secure elements) mounted on a vehicle (an example of a controlled object) in which a user can board. However, the present invention can also be applied to controlled objects other than vehicles, such as a control device for locking and unlocking the doors of a house, a control device for locking and unlocking the doors of a locker in which items are stored, and a control device for restricting the destination floors of an elevator with a key.

[1. Overview of communication system S]
First, a schematic configuration of a communication system S according to the present embodiment will be described with reference to Fig. 1 and the like. The communication system S is a system in which each of a plurality of eSEs mounted on a vehicle C can write a key (digital key) used to control each of a plurality of facilities in the vehicle C to each memory (for example, a non-volatile memory of each eSE). Fig. 1 is a diagram showing a schematic configuration example of the communication system S according to the present embodiment. As shown in Fig. 1, the communication system S includes a device 1 that is outside the vehicle C and is possessed by a user, an ECU (Electronic Control Unit) 2 mounted on the vehicle C, a parent eSE 3a (an example of a first electronic information storage medium) mounted on the vehicle C, and a child eSE 3b (an example of a second electronic information storage medium) mounted on the vehicle C.

The device 1 and the ECU 2 are capable of short-range wireless communication using, for example, NFC (Near field communication), Bluetooth (registered trademark), or UWB (Ultra Wide Band) technology. The user is a passenger of the vehicle C. If there are multiple passengers of the vehicle C (for example, when the vehicle C is used by a family), there may be a device 1 for each passenger. In this case, the devices 1 are distinguished as device 1-1, 1-2, etc. The parent eSE 3a holds, for example, a key used to control the engine (an example of equipment) of the vehicle C. The child eSE 3b holds, for example, a key used to control the doors (an example of equipment) of the vehicle C. If the vehicle C is equipped with four doors, a child eSE 3b for each door may be installed. In this case, the child eSE 3b is distinguished as child eSE 3b-1, 3b-2, etc.

Fig. 2 is a diagram showing an example of the schematic configuration of device 1. As shown in Fig. 2, device 1 is configured with a wireless communication unit 11, a memory unit 12, an operation/display unit 13, and a control unit 14. For example, a mobile phone or a smartphone can be used as device 1. Wireless communication unit 11 is a wireless communication device that has an antenna and performs contactless communication using NFC, Bluetooth, or UWB technology, and performs wireless communication with a communication partner (e.g., ECU 2) within a range where short-distance wireless communication is possible.

The storage unit 12 stores an operating system (OS) and applications. The applications include a pairing processing program. The storage unit 12 also stores in advance a key pair of the public key and private key of the device 1 (itself). This key pair is used for pairing a key (common key) with the parent eSE 3a. The common key obtained by the pairing is written to the storage unit 12. The operation/display unit 13 includes, for example, a display (touch panel) having an input function for accepting user operations and a display function for displaying various screens.

The control unit 14 is configured with a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), etc. The control unit 14 executes key pairing with the parent eSE 3a via the ECU 2 according to a pairing processing program. Pairing refers to a procedure in which each party exchanges public keys and generates a shared key using its own private key and the communication partner's public key. Such pairing may utilize ECDH (Elliptic curve Diffie-Hellman key exchange) technology. In this case, the parameters of the elliptic curve are known between the device D and the parent eSE 3a.

The ECU 2 is a control device that controls the vehicle C. The ECU 2 is mounted, for example, inside a center console. FIG. 3 is a diagram showing an example of a schematic configuration of the ECU 2. As shown in FIG. 3, the ECU 2 is configured to include a wireless communication unit 21, an interface (I/F) unit 22, a storage unit 23, and a control unit 24. The wireless communication unit 21 is a wireless communication device that has an antenna and performs non-contact communication using NFC, Bluetooth, or UWB technology, and performs wireless communication with a communication partner (e.g., device 1) within a range where short-distance wireless communication is possible. The interface unit 22 serves as an interface between the parent eSE 3a and the child eSE 3b, and is electrically connected to the parent eSE 3a and the child eSE 3b. Examples of the interface include an SPI (Serial Peripheral Interface), an I ² C (Inter-Integrated Circuit), and an ISO7816 interface.

The memory unit 23 stores an operating system and applications. The applications include a vehicle control program and a data relay program. The control unit 24 is configured with a CPU, RAM, ROM, etc. The control unit 24 controls the electrical system related to unlocking the doors of the vehicle C and starting the engine, etc., according to the vehicle control program. The control unit 24 also relays data exchanged between the device 1 and the parent eSE 3a or child eSE 3b according to the data relay program. Data protocol conversion may be performed during such relaying.

The parent eSE3a is mounted, for example, by soldering inside the center console of the vehicle C so as not to be removable, and the child eSE3b is mounted, for example, by soldering inside the door of the vehicle C so as not to be removable. The parent eSE3a and the child eSE3b may each be, for example, an eUICC (embedded Universal Integrated Circuit Card) having high tamper resistance. FIG. 4 is a diagram showing an example of the general configuration of the parent eSE3a and the child eSE3b. As shown in FIG. 4, the parent eSE3a and the child eSE3b have the same configuration. The parent eSE3a and the child eSE3b are each configured to include an interface (I/F) unit 31, an interface (I/F) unit 32, a RAM 33, a NVM (Nonvolatile Memory) 34, and a CPU 35, etc.

The interface unit 31 of both the parent eSE 3a and the child eSE 3b serves as an interface with the ECU 2 and is electrically connected to the ECU 2. The interface unit 32 of the parent eSE 3a serves as an interface with the child eSE 3b and is electrically connected to the child eSE 3b. On the other hand, the interface unit 32 of the child eSE 3b serves as an interface with the parent eSE 3a and is electrically connected to the parent eSE 3a. Examples of these interfaces include SPI (Serial Peripheral Interface), I ² C (Inter-Integrated Circuit), and ISO7816 interfaces. FIG. 5 is a diagram showing an example of a connection state between the parent eSE 3a and the child eSE 3b. In the example of FIG. 5, the parent eSE 3a and the child eSEs 3b-1, 3b-2, 3b-3, and 3b-4 are connected to each other via the interface unit 32.

In the NVM34, both the parent eSE3a and the child eSE3b store an operating system and applications. The applications include a pairing processing program and a mutual authentication processing program. In addition, the NVM34 of the parent eSE3a stores in advance a key pair of the parent eSE3a's own public key and private key. In the NVM34 of the child eSE3b, a key pair of the child eSE3b's own public key and private key is stored in advance. Such a key pair is used for key pairing with the device 1. The common key obtained in the pairing is written to the NVM34 in association with a key ID for identifying the common key.

Furthermore, authentication data is pre-stored in NVM34 for both parent eSE3a and child eSE3b. The authentication data of parent eSE3a is used for mutual authentication with child eSE3b. The authentication data of child eSE3b is used for mutual authentication with parent eSE3a. The authentication data includes, for example, a secure channel encryption key, a secure channel MAC (Message Authentication Code) key, and a data encryption key. The session key obtained by mutual authentication is written to NVM34. The various keys included in the authentication data are different from the keys included in the above key pair.

The CPU 35 of the parent eSE 3a is an example of the writing means, mutual authentication means, and transmission means of the present invention. The CPU 35 of the parent eSE 3a performs key pairing with the device 1 via the interface unit 31 and the ECU 2 in accordance with the pairing processing program. If the parent eSE 3a is inoperable due to a malfunction or the like, the CPU 35 of the child eSE 3b may perform key pairing with the device 1 on behalf of the parent eSE 3a. This makes it possible to avoid inconveniences such as the door of the vehicle C not being unlocked from the device 1 via the child eSE 3b due to the parent eSE 3a being inoperable.

In addition, the CPU 35 of the parent eSE3a performs mutual authentication with the CPU 35 of the child eSE3b via the interface unit 32 and the ECU 2 in accordance with the mutual authentication processing program. If necessary, a retry count may be set for the mutual authentication to prevent unauthorized key acquisition. The CPU 35 of the parent eSE3a then transmits the common key obtained by the pairing and a command to write the common key to NVM34 (an example of memory) to the child eSE3b through the secure session established by the mutual authentication. As a result, the CPU 35 of the child eSE3b writes the common key to NVM34 in response to the command from the parent eSE3a. Then, when the common key and a command to write the common key to NVM34 are sent to child eSE3b, the CPU35 of parent eSE3a writes data indicating that the common key has been sent (e.g., a child eSE distributed flag) to NVM34 in association with the common key and its key ID.

The common key and the command to write the common key may be transmitted by a command APDU (Application Protocol Data Unit). The command APDU is composed of a header including CLA (command class), INS (command code), P1 and P2 (parameters), and a body including data including the common key. The command APDU including the command to write the common key may be a PUT KEY (DATA) command that sets the common key.

Also, as shown in FIG. 5, when multiple child eSEs 3b are connected to a parent eSE 3a, the CPU 35 of the parent eSE 3a transmits the common key obtained by the pairing and a command to write the common key to the NVM 34 to each child eSE 3b (child eSEs 3b-1, 3b-2, 3b-3, and 3b-4 in the example of FIG. 5) through the secure session established by the mutual authentication. As a result, the CPU 35 of each child eSE 3b writes the common key to the NVM 34 in response to the command from the parent eSE 3a. In this case, the CPU 35 of the parent eSE 3a writes data (e.g., a child eSE distribution flag) that can distinguish whether the common key has been transmitted for each child eSE 3b to the NVM 34 in association with the common key and its key ID. This allows the sharing status of the common key to be managed efficiently.

In addition, when the parent eSE3a performs wireless communication with multiple devices 1 (e.g., device 1-1 and device 1-2), the CPU35 of the parent eSE3a writes each common key obtained by performing key pairing with each of the multiple devices 1 to the NVM34, distinguishing the common keys for each device 1 by the key ID. Then, the CPU35 of the parent eSE3a transmits each common key obtained by performing key pairing with each of the multiple devices 1 and a command to write the common key to the NVM34 to one or more child eSE3b through the secure session established by the mutual authentication. When the common key and a command to write the common key to the NVM34 are transmitted to the child eSE3b, the CPU35 of the parent eSE3a writes data indicating that the common key has been transmitted (e.g., a child eSE distribution flag) to the NVM34, distinguishing the common key for each device 1 and corresponding to the common key and its key ID. This allows for efficient management of the shared key status for each device 1 (in other words, for each key ID).

Figure 6 (A) is a diagram showing an example in which a common key (key value), its key ID, and a child eSE distribution flag obtained by pairing with device 1-1 are stored in association with each other, and Figure 6 (B) is a diagram showing an example in which a common key (key value), its key ID, and a child eSE distribution flag obtained by pairing with device 1-2 are stored in association with each other. Note that the lowest 4 bits of the child eSE distribution flag shown in Figures 6 (A) and (B) correspond to each of child eSEs 3b-1, 3b-2, 3b-3, and 3b-4. In the example of Figure 6 (A), the child eSE distribution flag is "0x0F" and the lowest 4 bits are "1111", so it is determined that the common key identified by the key ID "01" has been transmitted (distribution completed) to all child eSEs 3b-1, 3b-2, 3b-3, and 3b-4. On the other hand, in the example of FIG. 6(B), the child eSE distribution flag is "0x00" and the lowest 4 bits are "0000", so it is determined that the common key identified by the key ID "02" has not been transmitted to any of the child eSEs 3b-1, 3b-2, 3b-3, and 3b-4 (distribution incomplete).

2. Operation of communication system S
Next, the operation of the communication system S will be described with reference to Fig. 7. Fig. 7(A) is a flowchart showing an example of pairing processing performed by the CPU 35 in the parent eSE 3a. Fig. 7(B) is a flowchart showing an example of mutual authentication processing performed by the CPU 35 in the parent eSE 3a.

The pairing process shown in FIG. 7(A) is started, for example, when device 1 enters a range where short-distance wireless communication with parent eSE 3a is possible. When the pairing process shown in FIG. 7(A) is started, parent eSE 3a executes key pairing with device 1 (step S1). Next, parent eSE 3a generates a key ID for identifying the common key obtained by the pairing in step S1, writes the common key and the key ID in association with each other in NVM 34 (step S2), and terminates the pairing process shown in FIG. 7(A). Note that each common key obtained by pairing with each of the multiple devices 1 is written to each device 1, distinguished by the key ID.

The mutual authentication process shown in FIG. 7(B) is started, for example, periodically or irregularly. When the mutual authentication process shown in FIG. 7(B) is started, the parent eSE3a refers to the child eSE distribution flag to determine whether or not there is a common key that has not been sent to the child eSE3b (step S11). If the parent eSE3a determines that there is no common key that has not been sent to the child eSE3b (step S11: NO), the parent eSE3a ends the mutual authentication process shown in FIG. 7(B). On the other hand, if the parent eSE3a determines that there is a common key that has not been sent to the child eSE3b (step S11: YES), the parent eSE3a selects the unsent common key (for example, by key ID) (step S12) and performs mutual authentication with the child eSE3b (step S13).

Now, with reference to FIG. 8, the details of the mutual authentication in step S13 will be described. FIG. 8 is a sequence diagram showing the details of the mutual authentication in step S13. In FIG. 8, the parent eSE3a generates a parent random number (step S131) and transmits an INITIALIZE UPDATE command (APDU) including the parent random number and a Key Version Number to the child eSE3b (step S132). Here, the INITIALIZE UPDATE command is a command for notifying the child eSE3b of the start of mutual authentication for establishing a secure channel that serves as an encrypted path between the parent eSE3a and the child eSE3b. The Key Version Number is data used to identify authentication data that is the basis of the encryption calculation.

Next, when the child eSE3b receives the INITIALIZE UPDATE command from the parent eSE3a, it generates a child random number, a session key, and a child ciphertext (Cryptogram) (step S133) and transmits a response including the child random number and the child ciphertext to the parent eSE3a (step S134). Here, the session key is an encryption key used in a secure channel, and is generated, for example, based on the parent random number, the child random number, and authentication data. Such authentication data is obtained from the NVM34 by the Key Version Number. The session key generated in this manner includes, for example, an encryption session key and a MAC session key. The child ciphertext is generated, for example, by encrypting data obtained by concatenating the parent random number and the child random number according to the child rules with the encryption session key.

Next, when the parent eSE3a receives a response from the child eSE3b, it generates a session key and a child ciphertext in the same manner as the child eSE3b (step S135). Next, the parent eSE3a verifies the legitimacy of the child eSE3b by comparing the child ciphertext included in the response from the child eSE3b with the child ciphertext generated in step S135 (step S136). Next, when the parent eSE3a succeeds in verifying the legitimacy of the child eSE3b (i.e., authentication is successful), it generates a parent ciphertext (Cryptogram) by encrypting data obtained by concatenating the parent random number and the child random number according to the parent rules with the encryption session key (step S137), and transmits an EXTERNAL AUTHENTICATE command including the parent ciphertext to the child eSE3b (step S138). Here, the EXTERNAL AUTHENTICATE command is a command used by the child eSE3b to authenticate the parent eSE3a and determine the security level. The EXTERNAL AUTHENTICATE command may include a MAC generated using a MAC session key.

Next, when the child eSE3b receives the EXTERNAL AUTHENTICATE command from the parent eSE3a, it generates a parent ciphertext in the same manner as the parent eSE3a (step S139). The child eSE3b may generate a MAC in the same manner as the parent eSE3a. The child eSE3b then verifies the legitimacy of the parent eSE3a by comparing the parent ciphertext included in the EXTERNAL AUTHENTICATE command from the parent eSE3a with the parent ciphertext generated in step S139 (step S140). The child eSE3b may also verify the legitimacy of the MAC by comparing the MAC included in the EXTERNAL AUTHENTICATE command from the parent eSE3a with the MAC generated in step S139. Next, if the child eSE3b succeeds in validating the parent eSE3a, or if both the validity verification of the MAC and the validity verification of the parent eSE3a are successful, it sends a response indicating successful authentication to the parent eSE3a (step S141). This causes the parent eSE3a to record successful authentication. Thus, if mutual authentication between the parent eSE3a and the child eSE3b is successful, a secure channel between the parent eSE3a and the child eSE3b is established. Note that if the validity verification of the parent eSE3a fails, a response indicating failed authentication is sent to the parent eSE3a.

Next, in step S14 shown in FIG. 7B, the parent eSE3a judges whether the authentication is successful. If the authentication success is not recorded in the mutual authentication in step S14, it is judged that the authentication is not successful (step S14: NO), an error process such as an alarm output is performed (step S15), and the process returns to step S11. On the other hand, if the authentication success is recorded in the mutual authentication in step S13, it is judged that the authentication is successful (step S14: YES), and the parent eSE3a acquires the common key selected in step S12 from the NVM34, and transmits a PUT KEY command including the acquired common key and a write and set command for the common key to the child eSE3b through the secure session established by the mutual authentication (step S16). As a result, the child eSE3b writes the common key to the NVM34 in response to the above command from the parent eSE3a. Next, the parent eSE3a writes a child eSE distributed flag indicating that the shared key selected in step S12 has been transmitted to the NVM34 in association with the shared key and its key ID (step S17), returns to step S11, and determines whether there are any shared keys other than the one already selected, and executes the process as described above.

Note that even if the device 1 enters a range where short-distance wireless communication with the parent eSE3a is possible, if the pairing process does not start even after a predetermined time has elapsed, the child eSE3b may perform the processes of steps S1 and S2 shown in FIG. 7A on behalf of the parent eSE3a. Here, the fact that the pairing process has not started even after the predetermined time has elapsed may be detected, for example, by the ECU2. In this case, a command to start the pairing process is output from the ECU2 to the child eSE3b. The device 1 may then notify the user of the device 1 that key pairing has been performed by the child eSE3b. Such a notification may be made by display output or audio output. This allows the user to quickly take action such as replacing the parent eSE3a.

As described above, according to the above embodiment, the parent eSE3a, which communicates with the device 1 via the ECU 2, writes the common key obtained by performing key pairing with the device 1 to the NVM 34, the parent eSE3a performs mutual authentication with the child eSE3b, and the parent eSE3a transmits the common key obtained by the pairing and a command to write the common key to the NVM 34 to the child eSE3b through the secure session established by the mutual authentication, thereby enabling efficient sharing of the common key in the vehicle C.

In the above embodiment, if the parent eSE3a becomes inoperable due to a malfunction or the like after the common key is written to the NVM34 of each of the parent eSE3a and the child eSE3b, the parent eSE3a is replaced with an eSE (an example of a third electronic information storage medium) other than the parent eSE3a and the child eSE3b mounted on the vehicle C. In this case, the child eSE3b performs mutual authentication with the replaced eSE (hereinafter referred to as the "replaced eSE"), and transmits the common key held in the NVM34 and a command to write the common key to the NVM of the replaced eSE through the secure session established by the mutual authentication to the replaced eSE. The replaced eSE then writes the common key to the NVM in response to the command from the child eSE3b. Alternatively, the replaced eSE may perform mutual authentication with the child eSE3b, and transmit a command to transmit the common key stored in the NVM34 of the child eSE3b to the child eSE3b through the secure session established by the mutual authentication. For example, a GET KEY (DATA) command including such a command is transmitted to the child eSE3b. In this case, the child eSE3b acquires a common key and a key ID from its own NVM34 in response to the command, and transmits a response including the acquired common key to the replaced eSE through the secure session established by the mutual authentication. Then, the replaced eSE writes the common key included in the response from the child eSE3b to the NVM. According to the above configuration, even if the parent eSE3a is replaced by the replaced eSE, the common key can be quickly shared among multiple eSEs including the replaced eSE.

1 Device 2 ECU
3a Parent eSE
3b Child eSE
11 Wireless communication unit 12 Memory unit 13 Operation and display unit 14 Control unit 21 Wireless communication unit 22 Interface unit 23 Memory unit 24 Control unit 31 Interface unit 32 Interface unit 33 RAM
34 NVM
35 CPU
S Communication System

Claims (10)

In a system in which a plurality of electronic information storage media mounted on a controlled object can each write a key used for controlling a plurality of pieces of equipment within the controlled object into a respective memory, a first electronic information storage medium communicates with a device outside the controlled object among the plurality of electronic information storage media,
A writing means for writing a key obtained by performing key pairing with the device into a memory;
a mutual authentication means for performing mutual authentication with a second electronic information storage medium among the plurality of electronic information storage media;
a transmitting means for transmitting the obtained key and a command for writing the key to a memory to the second electronic information storage medium through a secure session established by the mutual authentication;
An electronic information storage medium comprising: The first electronic information storage medium according to claim 1, characterized in that when the key and a command to write the key to memory are transmitted to the second electronic information storage medium, the writing means writes data indicating that the key has been transmitted to the memory in association with the key. The first electronic information storage medium described in claim 2, characterized in that when there are multiple second electronic information storage media among the multiple electronic information storage media, the writing means writes data that can distinguish whether the key has been transmitted or not for each second electronic information storage medium in correspondence with the key into the memory. the first electronic information storage medium is capable of wireless communication with a plurality of devices;
the writing means writes, into a memory, each of the keys obtained by executing key pairing with each of the plurality of devices in a manner distinguished for each of the devices;
The first electronic information storage medium described in any one of claims 1 to 3, characterized in that the transmission means transmits to the second electronic information storage medium, via a secure session established by the mutual authentication, each key obtained by performing key pairing with each of the multiple devices and an instruction to write each key to memory. The first electronic information storage medium according to claim 4, characterized in that when the key and a command to write the key to memory are transmitted to the second electronic information storage medium, the writing means writes data indicating that the key has been transmitted to the memory in correspondence with the key, distinguishing between the devices. 1. A method for sharing a key in a system in which a plurality of electronic information storage media mounted on a controlled object can write a key used for controlling a plurality of pieces of equipment in the controlled object into each memory, the method comprising:
A step of writing a key obtained by a first electronic information storage medium, which communicates with a device outside the controlled object among the plurality of electronic information storage media, performing key pairing with the device into a memory;
performing mutual authentication between the first electronic information storage medium and a second electronic information storage medium among the plurality of electronic information storage media;
the first electronic information storage medium transmitting the obtained key and a command to write the key to a memory to the second electronic information storage medium through a secure session established by the mutual authentication;
the second electronic storage medium writing the key to a memory in response to the instruction from the first electronic storage medium;
A key sharing method comprising: If the first electronic information storage medium is inoperable, the second electronic information storage medium performs key pairing with the device on behalf of the first electronic information storage medium, and writes the key obtained by the second electronic information storage medium to a memory;
the device notifying a user of the device that the key pairing has been performed by the second electronic information storage medium;
The method of claim 6, further comprising: When the first electronic information storage medium is replaced with a third electronic information storage medium other than the plurality of electronic information storage media after the key is written in the memory of each of the first electronic information storage medium and the second electronic information storage medium, the second electronic information storage medium performs mutual authentication with the third electronic information storage medium;
a step of transmitting the written key and a command for writing the key to a memory from the second electronic information storage medium to the third electronic information storage medium through a secure session established by the mutual authentication;
the third electronic storage medium writing the key to a memory in response to the instruction from the second electronic storage medium;
The key sharing method according to claim 6 or 7, further comprising: When the first electronic information storage medium is replaced with a third electronic information storage medium other than the plurality of electronic information storage media after the key is written in the memory of each of the first electronic information storage medium and the second electronic information storage medium, the third electronic information storage medium performs mutual authentication with the second electronic information storage medium;
transmitting an instruction from the third electronic information storage medium to the second electronic information storage medium through the secure session established by the mutual authentication, the instruction causing the third electronic information storage medium to transmit the key;
The second electronic information storage medium acquires the key from the memory in response to the command from the third electronic information storage medium, and transmits the acquired key to the third electronic information storage medium through a secure session established by the mutual authentication;
the third electronic storage medium writing the key from the second electronic storage medium to a memory;
The key sharing method according to claim 6 or 7, further comprising: In a system in which a plurality of electronic information storage media mounted on a controlled object can each write a key used for controlling a plurality of pieces of equipment within the controlled object into the respective memories, a computer included in a first electronic information storage medium communicates with a device outside the controlled object among the plurality of electronic information storage media,
A writing means for writing a key obtained by performing key pairing with the device into a memory;
a mutual authentication means for performing mutual authentication with a second electronic information storage medium among the plurality of electronic information storage media;
A program that functions as a transmission means for transmitting the obtained key and a command for writing the key to a memory to the second electronic information storage medium through a secure session established by the mutual authentication.

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