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

Claim 8:
9. A security access key management method in a vehicle master device comprising a data communication module that is mounted in a vehicle and a central gateway that is mounted in the vehicle, the central gateway includes one or more computers, the security access key management method comprising:
receiving, with the data communication module, update data and rewrite specification data from outside of the vehicle via a wireless communication network;
communicating, with the data communication module, the rewrite specification data and the update data to the central gateway via a first communication bus inside of the vehicle;
communicating, with the central gateway, 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;
acquiring, with the one or more computers, 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, with the one or more computers, the rewrite specification data;
storing, with the one or more computers, 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 plurality of decryption keys stored corresponding to a respective electronic control unit of the plurality of electronic control units;
extracting, with the one or more computers, 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, with the one or more computers, a decryption key corresponding to the rewrite target electronic control unit from the plurality of decryption keys stored;
decrypting, with the one or more computers, the extracted key derivation value using the selected decryption key; generating, with the one or more computers, a security access key based on the decrypted extracted key derivation value;
authenticating, with the one or more computers, the rewrite target electronic control unit using the security access key; and
distributing, with the central gateway and after successful authentication of the rewrite target electronic control unit with the security access key, the update data to the rewrite target electronic control unit and instructing the rewrite target electronic control unit to rewrite a program.