| 摘要 |
According to the present invention, confidentiality or security of a network can be improved in a communication system including a plurality of devices which are mutually connected over a network and which transmit and receive packets. Devices between which packets are transmitted and received comprise mutually corresponding packet counters. The same random number is given to the packet counters as their initial values, and the packet counters are updated in response to packet transmission/reception. A transmission-side device generates a MAC value based on a message to be transmitted, extracts part of the MAC value based on a counted value of its own packet counter, sets the part of the MAC value as a divided MAC value, generates a packet by adding the divided MAC value to the message, and transmits the packet to a network. A reception-side device generates a MAC value based on a message included in a received packet, extracts part of the MAC value based on a counted value of its own packet counter, and compares the part of the MAC value with a divided MAC value in the received packet, thereby performing message authentication. |
