Patent ID: 8549284

Claim:
A method of performing a certificate validity check between a vehicle receiving a message and an entity transmitting the message in a vehicle-to-entity communication system, the method comprising the steps of: receiving, by the vehicle, the message transmitted from an the entity, the message having a digital certificate; determining, by a processing unit of the vehicle, whether the digital certificate is expired; determining, by the processing unit of the vehicle, whether the digital certificate is not listed in a local certificate revocation list stored in a memory of the vehicle in response to a determination that the digital certificate is not expired, otherwise, disregarding the message; determining, by the processing unit of the vehicle, an elapsed time since a last freshness check in response to the digital certificate not listed in the local certificate revocation list, the freshness check relating to the elapsed time since the freshness check was performed for verifying a validity of the digital certificate; comparing, by the processing unit of the vehicle, the elapsed time to a threshold requirement, the threshold requirement being based on a probabilistic technique, wherein the message is accepted for additional processing in response to the freshness check meeting the threshold requirement, otherwise, disregarding the message; wherein the probabilistic technique further comprises the steps of: determining a probability threshold that is a based on the elapsed time of the freshness check, the elapsed time since a last freshness check is verified by the following formula: ( I− 1)Δ< t f ≦IΔ where I is a count value, t f is the elapsed time since a last freshness check, and Δ is an interval constraint; generating a uniform random variable; and comparing the probability threshold with the uniform random variable for determining whether to accept the digital message.