A computer-implemented method for authenticating messages in a control area network is described. In one embodiment, a message identifier for a data message is ascertained. Each device is associated with one or more message identifiers. The data message is sent from a first device to a second device. The data message is associated with the ascertained message identifier. An authentication code computed by the first device is sent to the second device. The authentication code is sent by the first device in the data message or in an authentication message.