Reuse system, key generation device, data security device, in-vehicle computer, reuse method, and computer program

A reuse system, comprising:

• a key generation device;
• and
• a data security device that is detached from a first vehicle and is installed in a second vehicle,
• wherein the key generation device includes,
• a vehicle interface configured to transmit and receive data to and from the second vehicle,
• a key generation unit configured to generate a third key that is the same as a key that is stored in the data security device from a time when the data security device was installed in the first vehicle by using a device identifier of the data security device and a master key that is common to the first vehicle and the second vehicle, and
• an cryptographic processing unit configured to encrypt a fourth key of an in-vehicle computer that is installed in the second vehicle with the third key to generate an encrypted fourth key,
• wherein the encrypted fourth key is transmitted to the second vehicle through the vehicle interface, and
• the data security device includes,
• a first interface unit configured to transmit and receive data to and from an external device of the data security device,
• a first storage unit configured to store the third key from a time when the data security device was installed in the first vehicle, and
• a first cryptographic processing unit configured to decrypt the encrypted fourth key, which is received from the key generation device through the first interface unit, with the third key that is stored in the first storage unit.

A key generation device comprising:

• a vehicle interface configured to transmit and receive data to and from a second vehicle in which an in-vehicle computer detached from a first vehicle is installed;
• and
• a key generation unit configured to generate a first key that is the same as a key stored in the in-vehicle computer from a time when the in-vehicle computer was installed in the first vehicle by using an in-vehicle computer identifier of the in-vehicle computer, and a master key that is common to the first vehicle and the second vehicle,
• wherein the first key is transmitted to the second vehicle though the vehicle interface.

A data security device that is installed in a second vehicle in which an in-vehicle computer detached from a first vehicle is installed, the data security device comprising:

• a first interface unit configure to transmit and receive data to and from an external device of the data security device;
• and
• a first cryptographic processing unit configure to encrypt first data, which is applied to the in-vehicle computer, with a first key received from a key generation device through the first interface unit to generate encrypted first data,
• wherein the encrypted first data is transmitted to the in-vehicle computer through the first interface unit.

An in-vehicle computer that is detached from a first vehicle and is installed in a second vehicle, the in-vehicle computer comprising:

• a second interface unit configured to transmit and receive data to and from an external device of the in-vehicle computer,
• a second storage unit configured to store a first key from a time when being installed in the first vehicle;
• and
• a second cryptographic processing unit configured to decrypt encrypted first data, which is received from a data security device through the second interface unit, with the first key that is stored in the second storage unit.

A key generation device comprising:

• a vehicle interface configured to transmit and receive data to and from a second vehicle in which a data security device detached from a first vehicle is installed;
• a key generation unit configured to generate a third key that is the same as a key stored in the data security device from a time when the data security device was installed in the first vehicle by using a device identifier of the data security device, and a master key that is common to the first vehicle and the second vehicle;
• and
• a cryptographic processing unit configured to encrypt a fourth key of an in-vehicle computer that is installed in the second vehicle with the third key to generate an encrypted fourth key,
• wherein the encrypted fourth key is transmitted to the second vehicle with the vehicle interface.

A data security device that is detached from a first vehicle and is installed in a second vehicle, the data security device comprising:

• a first interface unit configured to transmit and receive data to and from an external device of the data security device;
• a first storage unit configured to store a third key from a time when being installed in the first vehicle;
• and
• a first cryptographic processing unit configured to decrypt encrypted fourth key, which is received from the key generation device through the first interface unit, with the third key that is stored in the first storage unit.

A reuse method of an in-vehicle computer that is detached from a first vehicle and is installed in a second vehicle, the reuse method comprising:

• generating, by a key generation device, a first key that is the same as a key stored in the in-vehicle computer from a time when the in-vehicle computer was installed in the first vehicle by using an in-vehicle computer identifier of the in-vehicle computer and a master key that is common to the first vehicle and the second vehicle;
• transmitting, by the key generation device, the first key to the second vehicle through a vehicle interface that transmits and receives data to and from the second vehicle;
• encrypting, by a data security device, first data, which is applied to the in-vehicle computer, with the first key received from the key generation device through a first interface unit that transmits and receives data to and from an external device of the data security device to generate encrypted first data;
• transmitting, by the data security device, the encrypted first data to the in-vehicle computer through the first interface unit;
• and
• encrypting, by the in-vehicle computer, the encrypted first data, which is received from the data security device through a second interface unit that transmits and receives data to and from an external device of the in-vehicle computer, with the first key stored in a second storage unit of the in-vehicle computer from a time when the in-vehicle computer was installed in the first vehicle.

A reuse method of a data security device that is detached from a first vehicle and is installed in a second vehicle, the reuse method comprising:

• generating, by a key generation device, a third key that is the same as a key that is stored in the data security device from a time when the data security device was installed in the first vehicle by using a device identifier of the data security device and a master key that is common to the first vehicle and the second vehicle;
• encrypting, by the key generation device, a fourth key of an in-vehicle computer that is installed in the second vehicle with the third key to generate an encrypted fourth key;
• transmitting, by the key generation device, the encrypted fourth key to the second vehicle though a vehicle interface that transmits and receives data to and from the second vehicle;
• and
• decrypting, by the data security device, the encrypted fourth key, which is received from the key generation device through a first interface unit that transmits and receives data to and from an external device of the data security device, with the third key that is stored in a first storage unit of the data security device from a time when being installed in the first vehicle.

A non-transitory computer-readable recording medium storing a computer program that causes a computer of a key generation device, which includes a vehicle interface that transmits and receives data to and from a second vehicle on which a data security device detached from a first vehicle is installed, to realize processing of:

• generating a third key that is the same as a key that is stored in the data security device from a time when the data security device was installed in the first vehicle by using a device identifier of the data security device and a master key that is common to the first vehicle and the second vehicle;
• encrypting a fourth key of an in-vehicle computer that is installed in the second vehicle with the third key to generate an encrypted fourth key;
• and
• transmitting the encrypted fourth key to the second vehicle through the vehicle interface.