US 12,445,423 B2
Communication device, vehicle, communication method, and recording medium recorded with program
Takahito Kiyokawa, Nisshin (JP)
Assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA, Toyota (JP)
Filed by TOYOTA JIDOSHA KABUSHIKI KAISHA, Toyota (JP)
Filed on Nov. 18, 2022, as Appl. No. 18/056,745.
Claims priority of application No. 2022-003365 (JP), filed on Jan. 12, 2022.
Prior Publication US 2023/0224289 A1, Jul. 13, 2023
Int. Cl. H04L 9/40 (2022.01); H04L 12/40 (2006.01)
CPC H04L 63/08 (2013.01) [H04L 12/40 (2013.01); H04L 2012/40215 (2013.01)] 8 Claims
OG exemplary drawing
 
1. A communication device comprising:
a memory; and
a processor coupled to the memory, wherein the processor is configured to:
receive, from each of a plurality of other communication devices, a message appended with authentication information generated by the other communication device;
for each of the received messages, authenticate the message based on an encryption key stored in the memory and on the authentication information appended to the message;
for each of the other communication devices or for each type of message,
determine that there is an abnormal-communication state in a case in which authentication has failed at least once and less than a specific number of times from among a plurality of authentications performed for a corresponding respective plurality of the messages, the abnormal-communication state being a state indicating that there are no abnormalities in a processor of the other communication device but the other communication device is being subjected to a security attack or a state indicating a malfunction in a communication function of the processor of the other communication device, and
determine that there is an abnormal state of the encryption key of the other communication device that generated the message in a case in which authentication has failed the specific number of times or greater from among the plurality of authentications performed for the corresponding respective plurality of the messages,
wherein the plurality of authentications is a number of times equivalent to a time required to get a device related to authentication ready from starting up of the processor, and
wherein the specific number of times is set such that a probability of the message being authenticated due to chance matches between a message authentication code generated from the message and a verification message authentication code based on the message is less than a failure rate of Level D ASIL (automotive safety integrity level).