Abstract: A vehicle communication network is monitored to detect a plurality of electronic control units (ECUs). Upon identifying a new ECU in the plurality of ECUs, a highest ECU trip counter is determined from the plurality of ECUs. A global trip counter stored in the memory is updated based on the highest ECU trip counter. The updated trip global trip counter is greater than the highest ECU trip counter. Then a replacement synchronization message is provided to the plurality of ECUs on the vehicle communication network. The replacement synchronization message includes the updated global trip counter.

Abstract: An onboard communication network of a vehicle is monitored to detect a plurality of available messages that include respective cipher-based message authentication codes (CMAC) and that were identified as eligible messages based on having an information entropy greater than a specified threshold. A first message is selected from the plurality of available messages. The CMAC of the selected message is input into a random number generator that outputs a random number seeded by the CMAC of the selected message. Then the random number is provided.

Abstract: A system for a vehicle includes a computer, a first electronic control module, and a wired vehicle communications network coupling the computer and the first electronic control module. The computer is programmed to transmit authentication keys to the first electronic control module and a plurality of second electronic control modules via the wired vehicle communications network, encrypt a table of the authentication keys using a first key, store the encrypted table, transmit the encrypted table to the first electronic control module via the wired vehicle communications network, and transmit the encrypted table and the first key to a remote server spaced from the wired vehicle communications network.

Abstract: A system includes a control module and a local server. The server is programmed to transmit a command to perform an operation to a plurality of vehicles including a vehicle including the control module. The command including a digital signature that is common across the vehicles. The control module is programmed to receive a temporary value; receive the command; decrypt the digital signature in the command with the temporary value; upon verifying the decrypted digital signature, perform the operation; and upon a metric incrementing to a threshold value, prevent decryption of the digital signature with the temporary value.

Abstract: Techniques for using a trip flag to detect desynchronization of trip counter values in a vehicle system. Techniques include a first electronic control unit (ECU) receiving a synchronization message including a trip counter and receiving a message from a second ECU including a trip flag. The trip flag includes a single bit of data generated by the second ECU. The first ECU compares the trip flag to a last bit of the trip counter stored at the first electronic control unit and processes the message in response to the trip flag matching the trip counter. The first ECU compares the trip counter to a previous trip counter based on the trip flag differing from the trip counter. The first ECU processes the message using the previous trip counter or increments the trip counter to process the message based on the comparison with the previous trip counter.

Abstract: A computer includes a processor and a memory storing instructions executable by the processor to, upon receiving an authorization message, transmit a plurality of new authentication keys to a respective plurality of control modules, the memory including an expiration time for the authorization message; update a listing of the control modules with respective statuses of the transmissions of the respective new authentication keys to the respective control modules, wherein each status is one of successful or unsuccessful; upon at least one status being unsuccessful, prevent the authorization message from expiring at the expiration time; after preventing the authorization message from expiring, retransmit the respective new authentication keys to each control module for which the respective status is unsuccessful; and then expire the authorization message.

Abstract: An onboard communication network of a vehicle is monitored to detect a plurality of available messages that include respective cipher-based message authentication codes (CMAC) and that were identified as eligible messages based on having an information entropy greater than a specified threshold. A first message is selected from the plurality of available messages. The CMAC of the selected message is input into a random number generator that outputs a random number seeded by the CMAC of the selected message. Then the random number is provided.

Abstract: A vehicle communication network is monitored to detect a plurality of electronic control units (ECUs). Upon identifying a new ECU in the plurality of ECUs, a highest ECU trip counter is determined from the plurality of ECUs. A global trip counter stored in the memory is updated based on the highest ECU trip counter. The updated trip global trip counter is greater than the highest ECU trip counter. Then a replacement synchronization message is provided to the plurality of ECUs on the vehicle communication network. The replacement synchronization message includes the updated global trip counter.

Abstract: A system for a vehicle includes a computer, a first electronic control module, and a wired vehicle communications network coupling the computer and the first electronic control module. The computer is programmed to transmit authentication keys to the first electronic control module and a plurality of second electronic control modules via the wired vehicle communications network, encrypt a table of the authentication keys using a first key, store the encrypted table, transmit the encrypted table to the first electronic control module via the wired vehicle communications network, and transmit the encrypted table and the first key to a remote server spaced from the wired vehicle communications network.

Abstract: A system includes a control module and a local server. The server is programmed to transmit a command to perform an operation to a plurality of vehicles including a vehicle including the control module. The command including a digital signature that is common across the vehicles. The control module is programmed to receive a temporary value; receive the command; decrypt the digital signature in the command with the temporary value; upon verifying the decrypted digital signature, perform the operation; and upon a metric incrementing to a threshold value, prevent decryption of the digital signature with the temporary value.

Abstract: A computer includes a processor and a memory storing instructions executable by the processor to, upon receiving an authorization message, transmit a plurality of new authentication keys to a respective plurality of control modules, the memory including an expiration time for the authorization message; update a listing of the control modules with respective statuses of the transmissions of the respective new authentication keys to the respective control modules, wherein each status is one of successful or unsuccessful; upon at least one status being unsuccessful, prevent the authorization message from expiring at the expiration time; after preventing the authorization message from expiring, retransmit the respective new authentication keys to each control module for which the respective status is unsuccessful; and then expire the authorization message.

Abstract: Techniques for using a trip flag to detect desynchronization of trip counter values in a vehicle system. Techniques include a first electronic control unit (ECU) receiving a synchronization message including a trip counter and receiving a message from a second ECU including a trip flag. The trip flag includes a single bit of data generated by the second ECU. The first ECU compares the trip flag to a last bit of the trip counter stored at the first electronic control unit and processes the message in response to the trip flag matching the trip counter. The first ECU compares the trip counter to a previous trip counter based on the trip flag differing from the trip counter. The first ECU processes the message using the previous trip counter or increments the trip counter to process the message based on the comparison with the previous trip counter.