Patent ID: 11876898
Assignee: DENSO CORPORATION
Field: Digital communication (Electrical engineering)
Classification: CPC H  G | IPC H

Claim 9:
10. A security access key management program stored in a non-transitory storage medium of a vehicle master device, the vehicle master device comprising:
a data communication module that is mounted in a vehicle and configured to receive update data and rewrite specification data from outside of the vehicle via a wireless communication network, and a central gateway that is mounted in the vehicle, the central gateway includes one or more computers, the data communication module communicating the rewrite specification data and the update data to the central gateway via a first communication bus inside of the vehicle, and the central gateway communicating the update data to a rewrite target electronic control unit of a plurality of electronic control units via a second communication bus inside of the vehicle;
the security access key management program causing the one or more computers of the central gateway to perform:
acquiring the rewrite specification data each time one of the plurality of electronic control units is updated either at the same time as acquisition of the update data or prior to acquisition of the update data;
analyzing the rewrite specification data;
storing a plurality of decryption keys for generation of corresponding security access keys, the security access keys used to perform device authentication of the plurality of electronic control units, the stored plurality of decryption keys being unreadable from outside of the central gateway and each decryption key of the stored plurality of decryption keys corresponding to a respective electronic control unit of the plurality of electronic control units;
extracting a key derivation value corresponding to the rewrite target electronic control unit from an analysis result of the rewrite specification data, the key derivation value being generated outside of the vehicle;
selecting a decryption key corresponding to the rewrite target electronic control unit from the stored plurality of decryption keys;
decrypting the extracted key derivation value using the selected decryption key;
generating a security access key based on the decrypted extracted key derivation value; and
authenticating the rewrite target electronic control unit using the security access key;
wherein after successful authentication of the rewrite target electronic control unit with the security access key, the central gateway distributes the update data to the rewrite target electronic control unit and instructs the rewrite target electronic control unit to rewrite a program.