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Publication Number
US-10691631-B2
Publication Date
2020-06-23
Expiration Date
Abstract
Various communication systems may benefit from appropriate filtering of communications. For example, a network having a broadcast bus, such as a controller area network, may benefit from a frame filter. For example, a method can include receiving a plurality of messages at an interface with a broadcast bus of a communication network for a system. The method can also include selectively permitting the plurality of messages to be conveyed through the interface based on comparing one or more of the plurality of messages to a specification for the interface.
Core Innovation
The invention relates to a broadcast bus frame filter for a communication network in which a broadcast bus has a broadcast bus clock. A plurality of messages is received at an interface, and the device selectively permits the messages to be conveyed through the interface by comparing one or more of the messages to a specification for the interface. The selective permitting is performed on a bit-by-bit basis, including conveying a first bit of a given message before analyzing a subsequent bit of the given message.
The selective permitting is transparent such that an impact on timing of message propagation on the broadcast bus is negligible and falls within an acceptable margin of error for the broadcast bus clock. The filter is implemented with isolated hardware-based filtering that forwards or filters bus messages through an interface by using a filter specification or filter list. Directionality is used so that different behavior applies depending on whether a message is received from a filtered side or an unfiltered side, including termination of unauthorized frames via error-frame generation and/or temporary electrical isolation.
The specification for the interface can be checked using broadcast bus identifier comparisons, broadcast bus protocol message analysis, and manufacturer-specific encoding of data field contents, as well as other checks described for the comparison. The broadcast bus frame filter is also used as a gateway ECU to forward cryptographically signed firmware-update messages, with cryptographic-signature authentication performed for message permission, and with the filter specification itself secured using cryptographically signed filter specifications and in-field updates so that per-ECU integration/retrofit is enabled without changes to other ECUs.
Claims Coverage
The identified independent claims are clm-00001, clm-00015, and clm-00017. Across the three independent claims, the coverage centers on bit-by-bit transparent selective permitting/forwarding through an interface based on comparing messages to an interface specification, with additional constraints regarding directionality-based distinct specifications and implementation as a broadcast bus controller/ECU apparatus.
Bit-by-bit transparent selective permitting on a broadcast bus clock
Receiving a plurality of messages at an interface with a broadcast bus for a system, the broadcast bus having a broadcast bus clock; selectively permitting the plurality of messages to be conveyed through the interface based on comparing one or more of the plurality of messages to a specification for the interface; performing the selectively permitting on a bit-by-bit basis including conveying a first bit of a given message before analyzing a subsequent bit; implementing the method in a network controller in a selected ECU; and making the selectively permitting transparent such that an impact on timing of message propagation on the broadcast bus is negligible and within an acceptable margin of error for the broadcast bus clock.
Directionality-specific interface specifications for bit-by-bit transparent selective permitting
Receiving a plurality of messages at an interface with a broadcast bus for a system, the broadcast bus having a broadcast bus clock; with a device, selectively permitting the plurality of messages to be conveyed through the interface based on comparing one or more of the plurality of messages to a specification for the interface; performing the selectively permitting on a bit-by-bit basis including conveying a first bit before analyzing a subsequent bit; using distinct specifications for the comparing based on the side of the interface from which the message is received; implementing the device as a selected ECU of a plurality of ECUs; and making the selectively permitting transparent such that an impact on timing of message propagation on the broadcast bus is negligible and within an acceptable margin of error for the broadcast bus clock.
ECU apparatus with receiver, processor comparison, and transmitter bit-by-bit transparent forwarding
Providing a receiver configured to receive a plurality of messages at an interface with a provided broadcast bus of a provided communication network for a provided system, the broadcast bus having a broadcast bus clock; providing a processor configured to perform a comparison of one or more of the plurality of messages to a specification for the interface; providing a transmitter configured to selectively forward the plurality of messages through the interface based on the comparison with selectively forwarding performed on a bit-by-bit basis including conveying through the interface a first bit of a given message before analyzing a subsequent bit; implementing the receiver, processor, and transmitter in a broadcast bus controller; wherein the apparatus is an ECU; and wherein the selectively forwarding is transparent such that an impact on timing of message propagation on the broadcast bus is negligible and within an acceptable margin of error for the broadcast bus clock.
The independent claims collectively require a transparent selective permitting/forwarding approach that operates on a bit-by-bit basis while keeping timing impact negligible relative to the broadcast bus clock. The claims further specify that the decision is based on comparing received messages to an interface specification, with one claim additionally requiring distinct specifications based on the side of the interface and another requiring an ECU/broadcast bus controller apparatus architecture with receiver, processor, and transmitter.
Stated Advantages
Transparent selective permitting/forwarding such that an impact on timing of message propagation on the broadcast bus is negligible and falls within an acceptable margin of error for the broadcast bus clock.
Documented Applications
Using the broadcast bus frame filter as a gateway ECU to forward cryptographically signed firmware-update messages.
Securing communication by using a cryptographically signed filter specification with in-field updates to enable per-ECU integration/retrofit without changes to other ECUs.
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