Patent attributes
A communication system and communication apparatus that can improve the stability and security of communication. In this communication system, a communication apparatus (101) generates, at a predetermined interval, a keep-alive message based on key information stored in a key information database part (113) and transmits the keep-alive message to a communication apparatus (102). The communication apparatus (102) receives the keep-alive message from the communication apparatus (101), and a key information updating part (157) updates (for example, corrects), based on this keep-alive message, the data stored in a key information database part (154). In this way, the information stored in the communication apparatus (101) and the information stored in the communication apparatus (102) can be made common, and problems, such as a communication interruption, caused by disagreement between the information stored in the communication apparatus (101) and the information stored in the communication apparatus (102) can be solved, resulting in improvement of the stability and security of communication between the two communication apparatuses.
