# US 8,788,731 B2 · Vehicle message filter

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- Number: US 8,788,731 B2
- Document ID: US8788731B2
- Status: Granted
- Kind: B2
- Application number: 13/561,515
- Filed: 2012-07-30
- Published: 2014-01-30
- Granted: 2014-07-22
- Earliest claimed: 2012-07-30
- Assignees: GM Global Technology Operations LLC
- Applicants: Kenneth L. Peirce; Thomas M. Forest
- Inventors: Kenneth L. Peirce; Thomas M. Forest
- Web page: https://patentgrep.com/patent/US8788731B2

## CPC

- H04L 67/12: specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks
- H04L 12/40032: {Details regarding a bus interface enhancer}
- H04L 63/0227: {Filtering policies (mail message filtering H04L51/212)}
- H04L 63/1416: {Event detection, e.g. attack signature detection}
- H04L 2012/40215: {Controller Area Network CAN}
- H04L 2012/40273: {the transportation system being a vehicle}
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

A message filtering system for a communications system in a vehicle enabling communication between various systems and subsystems via a vehicle bus. Electronic devices may be coupled to the bus. Electronic control units (ECUs) may be located therebetween. The ECU may regulate or control the flow of messages between the bus and the electronic devices. Message filters may apply a filter policy to incoming and outgoing messages. In addition, the message filtering system may have an alert policy for violations of the filter policy. In one embodiment, the source identity of outgoing messages may be overwritten by a message filter dedicated to outgoing messages; this message filter may be an application specific integrated circuit.

## Claims

### Claim 1

A message filtering system for a vehicle network, comprising:
a vehicle bus having a plurality of nodes for the transmission and reception of messages to and from the bus;
a plurality of electronic control unit (ECUs), each of the plurality of ECU being coupled to one of the nodes and each being associated with a different network device on the bus, wherein each of the plurality of ECU has a controller and a transmit filter of the plurality of ECU that is located between the controller and its respective node, wherein the transmit filter is configured with a filter policy that terminates the transmission of an outgoing message from the respective ECU prior to the message reaching the vehicle bus when if the message violates the filter policy.

### Claim 2 (depends on 1)

The message filtering system as defined in claim 1, wherein the network devices include: a telematics unit and one or more vehicle system modules (VSMs).

### Claim 3 (depends on 1)

The message filtering system as defined in claim 1, wherein the transmit filter is an application specific integrated circuit (ASIC).

### Claim 4 (depends on 3)

The message filtering system as defined in claim 3, wherein the ASIC is configured to overwrite a source identifier within the outgoing message.

### Claim 5 (depends on 1)

The message filtering system as defined in claim 1, wherein at least one of the transmit filters is physically isolated from its respective ECU.

### Claim 6 (depends on 1)

The message filtering system as defined in claim 1, wherein at least one of the transmit filters is logically isolated from its respective ECU.

### Claim 7 (depends on 1)

The message filtering system as defined in claim 1, further comprising a receive filter located between the controller and the respective node, wherein the receive filter complies with the filter policy which is used to determine whether an incoming message from the bus should be provided to the respective ECU, wherein the receive filter terminates the transmission of the message if the message violates the filter policy.

### Claim 8 (depends on 7)

The message filtering system as defined in claim 7, wherein at least one of the receive filters is physically and logically isolated from its respective ECU.

### Claim 9 (depends on 1)

The message filtering system as defined in claim 1, wherein the bus and plurality of ECUs comprise a local area network in the vehicle.

### Claim 10 (depends on 1)

The message filtering system as defined in claim 1, wherein the transmit filter is configured with an alert policy that generates an alert for a vehicle diagnostics system when a violation of the filter policy occurs.

### Claim 11 (depends on 10)

The message filtering system as defined in claim 10, wherein the configurations of the filter policy and the alert policy are updateable, wherein policy updates include a valid digital encryption signature.

### Claim 12 (depends on 11)

The message filtering system as defined in claim 11, wherein the filter policy and the alert policy are configured to provide an alert when a policy update is presented with an invalid digital encryption signature.

### Claim 13

A method of filtering messages in a vehicle network, comprising the steps of:
providing a vehicle area network having a plurality electronic control units (ECUs) each associated with a network device, the ECUs being interconnected via a bus, wherein at least two of the ECUs are associated with transmit filters having a filter policy and each being positioned between the bus and the respective ECU;
receiving at a first transmit filter an outgoing message from one of the at least two ECUs;
determining whether the outgoing message complies with the filter policy;
based on the determination, either:
terminating the outgoing message based upon a violation of the filter policy, or
transmitting the outgoing message onto the bus; and
when transmitted, receiving the outgoing message at the other of the at least two ECUs.

### Claim 14 (depends on 13)

The method as defined in claim 13, wherein the first transmit filter is an application specific integrated circuit (ASIC).

### Claim 15 (depends on 14)

The method as defined in claim 14, wherein outgoing message has a first source identifier (ID) and the transmitting step further comprises the first transmit filter overwriting the first source identifier with a second source identifier, wherein the second source identifier is associated with the respective ECU.

### Claim 16

A method of filtering messages in a vehicle area network, comprising:
providing a plurality of network device electronic control units (ECUs) coupled to a vehicle bus, wherein each of the plurality of network device ECUs has a transmit filter and is configured to apply a filter policy to outbound messages transmitted on the bus;
receiving at a first transmit filter of one of the plurality of network device ECUs an outbound a message from a processor associated with the respective ECU;
applying the filter policy to the outbound message; and
transmitting the outbound message if the message passes the filter policy, else discarding the message if the message fails to pass the filter policy.

### Claim 17 (depends on 16)

The method of claim 16, wherein each of the plurality of network device ECU has a receive filter that applies the filter policy to outbound messages transmitted over the vehicle bus when they are received at at least one of the respective ECUs.

### Claim 18 (depends on 17)

The method of claim 17, wherein the transmit filters, the receive filters, or both are isolated from the respective ECUs.

### Claim 19 (depends on 16)

The method of claim 16, further comprising reconfiguring the filter policy of the transmit filters, the receive filters, or both with an encrypted, new policy.

### Claim 20 (depends on 16)

The method of claim 16, wherein applying the filter policy further comprises overwriting a first source identifier of the outbound message with a second source identifier.