Long term key management architecture for SCADA systems

A SCADA key management is required to provide a key management protocol that will be used to secure the communication channel of the SCADA entities. The SCADA key management scheme often uses symmetric cryptography due to resource constraints of the SCADA entities. Normally the use of symmetric cryptography mechanism is in the form of pre-shared keys, which are installed manually and are fixed. Then, these pre-shared keys or long term keys are used to generate session keys. However, it is important that these long term keys can be updated and refreshed dynamically. With the nature of SCADA systems which may consist of hundreds of nodes deployed in different locations, manually updating and refreshing these long term keys is time consuming. Thus, this paper proposes an automatic long term key management method that updates and refreshes these keys efficiently. The proposed method provides a flexibility to refresh the long term keys and reduces the number of keys stored in the SCADA entities.