Communication node, key synchronization method, and key synchronization system

A key synchronization system for synchronizing an application key between a first communication node and a second communication node, wherein

• the first communication node comprises:
• a key synchronization controller that controls synchronization of an application key on the basis of a node-based signaling process and a session-based signaling process, where the former process is for starting or ending exchanging of the application key between the second communication node and the first communication node, and the latter process is for synchronizing a rule for assignment of the application key to a session with the second communication node, the session shared with the second communication node;
• and
• an application communicator that provides the application key in accordance with the rule, the key for use by a first application having the session, and wherein
• the second communication node comprises:
• a key synchronization controller that controls synchronization of an application key on the basis of a node-based signaling process and a session-based signaling process, where the former process is for starting or ending exchanging of the application key between the first communication node and the second communication node, and the latter process is for synchronizing a rule for assignment of the application key to a session with the first communication node, the session shared with the first communication node;
• and
• an application communicator that provides the application key in accordance with the rule, the key for use by a second application having the session.