Communications bus signal fingerprinting

A non-transitory computer program product comprising a computer-readable storage medium having computer-readable program instructions, which when executed result in operations comprising:

• monitoring, by a first data processor of a first security module of a first security zone and a second data processor of a second security module of a second security zone, a plurality of voltage lines of a first electronic control unit (ECU) and a second ECU, wherein each ECU is electrically coupled to a communications bus;
• measuring, by the first data processor and the second data processor, voltage differentials across at least two of the plurality of voltage lines of the first ECU and at least two of the plurality of voltage lines of the second ECU;
• comparing, by the first data processor and the second data processor, each voltage differential to a plurality of predetermined signal fingerprints associated with the first ECU and the second ECU, the plurality of predetermined signal fingerprints representing various voltages over time that characterize nominal operation of the first ECU and the second ECU;
• identifying, by at least one of the first data processor or the second data processor and based on the comparing, a variance in at least one of the compared voltage differentials relative to one or more of the plurality of predetermined signal fingerprints, the variance identifying whether signal transmissions on at least one of the plurality of voltage lines has been compromised;
• providing, by the at least one of the first data processor or the second data processor, data characterizing the identified variance;
• and
• encrypting, by an encryption device, the data characterizing the identified variance, wherein the encrypted data identifies an origination security zone of the data as either the first security zone or the second security zone based on which of the at least one of the first data processor or the second data processor identifies the variance.

A method for implementation by one or more data processors forming one or more computing devices, the method comprising:

• measuring, by a first data processor of a first security module of a first security zone and a second data processor of a second security module of a second security zone, a first voltage line of a first electronic control unit (ECU) and a second ECU during an imprint mode of the first security module and the second security module;
• determining, by the first data processor and the second data processor, a first signal fingerprint associated with the first ECU and a second signal fingerprint associated with the second ECU over time by comparing the measured first voltage line to a first ideal voltage associated with the first measured voltage line and (ii) the measured second voltage line to a second ideal voltage associated with the second measured voltage line;
• providing, by the first data processor and the second data processor, data characterizing the first signal fingerprint and the second signal fingerprint, each signal fingerprint representing various voltages over time that characterize nominal operation of the first ECU and the second ECU;
• and
• encrypting, by an encryption device, the data comprising the first signal fingerprint and the second fingerprint, wherein the encrypted data identifies an origination security zone of the data as the first security zone for the first signal fingerprint and the second security zone for the second signal fingerprint.