US Patent 9705678 Fast CAN message authentication for vehicular systems

A method for authenticating messages is provided. The method includes calculating a hash value based on a key and a message count value and receiving a data message associated with the message count value. The method includes receiving an authentication message that includes the message count value and a message authentication code derived from the data message, the message count value and the key. The method includes applying portions of the data message to look up portions of the hash value and combining the portions of the hash value to form a verification version of the message authentication code. The method includes determining whether the message authentication code matches the verification version of the message authentication code.