During the Session Key Change process, the DNP3 master generates a new pair of Session Keys and sends an encrypted copy of those Session Keys to the outstation. The DNP3 master encrypts the Session Keys using another key, the Update Key, and a Key Wrap algorithm. The Update Key permits the DNP3 master to change the Session Keys even after a Session Key is compromised.
Session Keys are changed on a regular basis to maintain security. The DNP3 master also initiates a Session Key Change whenever it re-establishes communications with an outstation.
Further Information
Define when ClearSCADA changes the Session Keys on a DNP3 master outstation: see Define When the Session Keys Need to Change.
Specify When the Slave Outstation is to Invalidate its Pair of Session Keys.