COMMUNICATION DEVICE, COMMUNICATION SYSTEM AND COMMUNICATION METHOD

摘要

The purpose of this communication device is to resume data transmission and reception between communication devices in a short time without sharing a key between the communication devices again, for example, even when a transmission-side communication device is restarted. This communication device is provided with: a volatile memory for storing a counter value; a creation unit for creating data in which the counter value is stored; a communication unit for transmitting the data to another communication device; a storage instruction unit for causing the volatile memory to update and store the counter value every time the communication unit transmits the data; and a nonvolatile memory. The counter value is added every time the communication unit transmits the data, the storage instruction unit causes the nonvolatile memory to store the counter value therein at predetermined intervals, and the creation unit stores a value obtained by adding a predetermined value to the counter value stored in the nonvolatile memory in the data when the communication device is restarted.