The SKS is the entity with knowledge of SecurityGroups and it maintains a mapping between Roles and SecurityGroups. The related User Authorization model is defined in OPC 10000-3. The User Authorization model defines the mapping of identities to Roles and the mechanism to set Permissions for Roles on a Node. The Permissions on a SecurityGroup Object is used to determine if a Role has access to the keys for the SecurityGroup.
An example for setting up a SecurityGroup and the configuration of affected Publishers and Subscribers is shown in Figure 9.
Figure 9 – SecurityGroup management sequence
To secure NetworkMessages, the NetworkMessages shall be secured with keys provided in the context of a SecurityGroup. A SecurityGroup is created on a SKS using the Method AddSecurityGroup.
To limit access to the SecurityGroup and therefore to the security keys, Permissions shall be set on the SecurityGroup Object. This requires the management of Roles and Permissions in the SKS.
To set the SecurityGroup relation on the Publishers and Subscribers, the SecurityGroupId and the SKS EndpointDescriptions are configured in a PubSub group.