Data communication system, center device, master device, and storage medium storing secret information exchange program

A center device that distributes update data to a master device, wherein

• the center device exchanges random secret information with the master device using an algorithm of a Diffie-Hellman key exchange (DHE) or an Elliptic curve Diffie-Hellman key exchange (ECDHE) for key distribution, encrypts an encryption key for encrypting update data based on the exchanged secret information, stores the encrypted encryption key in a campaign notification, places the update data encrypted with the encryption key in a content delivery network, and transmits the campaign notification storing the encrypted encryption key to a vehicle system to be reprogrammed.

A center device that distributes update data to a master device, wherein

• the center device uses a Diffie-Hellman key exchange (DHE) algorithm or an Elliptic curve Diffie-Hellman key exchange (ECDHE) algorithm for key distribution, exchanges secret information with the master device using a common random number for each vehicle model or each vehicle group as a secret key used for the algorithm of the DHE or the ECDHE, uses the exchanged secret information as an encryption key, encrypts update data based on the encryption key, places the encrypted update data encrypted with the encryption key in a content delivery network, stores the encrypted encryption key in a campaign notification, and transmits the campaign notification storing the encrypted encryption key to a vehicle system to be reprogrammed.

A master device that installs update data downloaded from a center device in an electronic control unit to be reprogrammed, wherein

• the center device encrypts an encryption key for encrypting the update data based on an exchanged secret information, stores the encrypted encryption key in a campaign notification, places the update data encrypted with the encryption key in a content delivery network, and transmits the campaign notification storing the encrypted encryption key to a vehicle system to be reprogrammed, and
• the master device exchanges random secret information with the center device using an algorithm of a Diffie-Hellman key exchange (DHE) or an Elliptic curve Diffie-Hellman key exchange (ECDHE) for key distribution.

A master device that installs update data downloaded from a center device in an electronic control unit to be reprogrammed, wherein

• the master device uses an algorithm of a Diffie-Hellman key exchange (DHE) or an Elliptic curve Diffie-Hellman key exchange (ECDHE) for key distribution, exchanges secret information with the center device using a random number according to a specific rule as a secret key used for the algorithm of the DHE or the ECDHE, acquires an encrypted encryption key from a campaign notification acquired from the center device, acquires the encryption key by decrypting the encrypted encryption key with the secret information, decrypts the encrypted update data after downloading to acquire the encrypted update date from a content delivery network, transmits the decrypted update data to an electronic control device to be reprogrammed, and installs the update data to the electronic control device.

A secret information exchange program for causing a center device that distributes update data to a master device to execute:

• a secret information exchange step of exchanging random secret information with a master device using an algorithm of a Diffie-Hellman key exchange (DHE) or an Elliptic curve Diffie-Hellman key exchange (ECDHE) for key distribution;
• and
• an encryption key distribution step of encrypting an encryption key for encrypting update data based on the exchanged secret information, storing the encrypted encryption key in a campaign notification, placing the update data encrypted with the encryption key in a content delivery network, and transmitting the campaign notification storing the encrypted encryption key to a vehicle system to be reprogrammed.

A non-transitory computer readable storage medium storing a secret information exchange program for causing a center device that distributes update data to a master device to execute:

• a secret information exchange step of using a Diffie-Hellman key exchange (DHE) algorithm or an Elliptic curve Diffie-Hellman key exchange (ECDHE) algorithm for key distribution, and exchanging secret information with the master device using a common random number for each vehicle model or each vehicle group as a secret key used for the algorithm of the DHE or the ECDHE;
• and
• an encryption key distribution step of using the exchanged secret information as an encryption key, encrypting update data based on the encryption key, placing the encrypted update data encrypted with the encryption key in a content delivery network, storing the encrypted encryption key in a campaign notification, and transmitting the campaign notification storing the encrypted encryption key to a vehicle system to be reprogrammed.

A non-transitory computer readable storage medium storing a secret information exchange program for causing a master device that installs update data downloaded from a center device in an electronic control unit to be reprogrammed to execute:

• a secret information exchange step of exchanging random secret information with a center device using a Diffie-Hellman key exchange (DHE) algorithm or an Elliptic curve Diffie-Hellman key exchange (ECDHE) algorithm for key distribution,
• wherein
• the center device encrypts an encryption key for encrypting the update data based on an exchanged secret information, stores the encrypted encryption key in a campaign notification, places the update data encrypted with the encryption key in a content delivery network, and transmits the campaign notification storing the encrypted encryption key to a vehicle system to be reprogrammed.

A non-transitory computer readable storage medium storing a secret information exchange program for causing a master device that installs update data downloaded from a center device in an electronic control unit to be reprogrammed to execute:

• a secret information exchange step of using an algorithm of a Diffie-Hellman key exchange (DHE) or an Elliptic curve Diffie-Hellman key exchange (ECDHE) for key distribution, exchanging secret information with the center device using a random number according to a specific rule as a secret key used for the algorithm of the DHE or the ECDHE, acquiring the encryption key from a campaign notification acquired from the center device, acquires the encryption key by decrypting the encrypted encryption key with the secret information, decrypting the encrypted update data after downloading to acquire the encrypted update date from a content delivery network, transmits the decrypted update data to an electronic control device to be reprogrammed, and installs the update data to the electronic control device.