CPC H04L 9/32 (2013.01) [G06F 7/588 (2013.01)] | 18 Claims |
1. A system, comprising a computer including a processor and a memory, the memory storing instructions executable by the processor to:
monitor an onboard communication network of a vehicle 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 a number of bits in the respective message that cannot be determined before the message is sent greater than a specified threshold;
select a first message from the plurality of available messages;
upon determining a length of the CMAC of the selected message is less than a length of a seed value specified by a random number generator that outputs a random number, select a second message from the plurality of available messages;
generate an updated CMAC by combining the CMAC of the second message and the CMAC of the first message;
input the updated CMAC into the random number generator based on determining a length of the updated CMAC is equal to the length of the seed value; and
then output the random number.
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