COMMUNICATION SYSTEM AND KEY INFORMATION SHARING METHOD

摘要

PROBLEM TO BE SOLVED: To provide a communication system and a key information sharing method in which a first communication device and a second communication device can share key information and perform encryption processing.SOLUTION: A monitoring device calculates a hash value based on duplicate data on storage contents of an ECU, and transmits part of the data as confirmation information to the ECU. If the received confirmation information is included in a hash value calculated by the ECU, the ECU further extracts part from a value obtained by extracting the confirmation information from the hash value calculated by the ECU, and transmits it as response information to the monitoring device. The monitoring device determines whether or not the received response information is included in the hash value calculated by the monitoring device. The ECU and the monitoring device use a residual value obtained by excluding the confirmation information and the response information from the hash value calculated by each of them as a common key and use it for encryption processing from then on.SELECTED DRAWING: Figure 7