US Patent 11711384 Method and system for detecting message injection anomalies

A method and system for detecting illegitimate messages injected into legitimate messages of a bus, such as a Controller Area Network (CAN) bus, are provided. Legitimate messages are broadcasted over the bus with a period whereby the legitimate messages are periodic legitimate messages. A controller connected to the bus receives at a first time instant a first message from the bus and receives at a second time instant a second message from the bus. The controller compares a first difference in time between the second time instant and the first time instant with a limit. The limit is two-thirds of the period. An anomaly is detected when the first difference in time is less than the limit.