Patent ID: 9331854
Filing Date: 2016-05-03
CPC Classification: H04L

Claim Text:
1. A message authentication method in a communication system, in which a plurality of ECUs are connected via a controller area network (CAN), the message authentication method comprising: a step of incrementing, by each of the plurality of ECUs other than a transmission ECU, a counter value that is stored in each of the plurality of ECUs other than the transmission ECU, when each of the plurality of ECUs other than the transmission ECU detects a main message having a message ID being transported on the CAN that the each of the ECUs may transmit or receive; a step of transmitting, by the transmission ECU, the main message; a step of incrementing, by the transmission ECU, the counter value when transmitting the main message; a step of transmitting, by the transmission ECU, an MAC message containing a message authentication code that is produced based on the main message and the counter value; a step of receiving, by a reception ECU, the main message; a step of receiving, by the reception ECU, the MAC message; and a step of verifying, by the reception ECU, validity of the main message according to whether or not the message authentication code that is produced based on the main message and the counter value matches the message authentication code contained in the MAC message.