Method for handling transmission of fraudulent frames within in-vehicle network

An in-vehicle network system including a plurality of electronic control units that exchange data frames, each having added thereto a message authentication code (MAC), via at least one bus in accordance with a Controller Area Network (CAN) protocol, the in-vehicle network system comprising:

• a first electronic control unit comprising
• one or more memories;
• and
• circuitry configured to:
• generate a first MAC using a first MAC key and a value of a first counter that counts a number of times a data frame having added thereto a MAC has been transmitted,
• add the first MAC to a data frame, and
• transmit the data frame on the at least one bus;
• and
• a second electronic control unit comprising
• one or more memories;
• and
• circuitry configured to:
• receive the data frame transmitted on the at least one bus,
• generate a second MAC by using a second MAC key and a value of a second counter that counts a number of times a data frame having added thereto a MAC has been received,
• perform verification that the data frame received has added thereto the second MAC,
• increment a number of error occurrences when the verification has failed for the data frame, the data frame including a predetermined message ID, and
• execute, when the number of error occurrences exceeds a predetermined threshold, a process associated in advance with the predetermined message ID.

An electronic control unit for performing communication via a bus in accordance with a Controller Area Network (CAN) protocol, the electronic control unit comprising:

• one or more memories;
• and
• circuitry configured to:
• receive a data frame from the bus,
• generate a first message authentication code (MAC) using a MAC key and a value of a counter that counts a number of times a data frame having added thereto a MAC has been received,
• perform verification that the data frame received has added thereto the first MAC,
• increment a number of error occurrences when the verification has failed for the data frame, the data frame including a predetermined message ID, and
• execute, when the number of error occurrences exceeds a predetermined threshold, a process associated in advance with the predetermined message ID.