| Previous | Table of Contents | Next |
Through DAIS an operator gets access to data in a control system. The operator can:
• Read data (Data Access) and alarms and events (Alarms & Events).
• Write data (Data Access)
• Acknowledge alarms (Alarms & Events).
Many control systems implement an authorization scheme where it checks if an operator is allowed to read, write, or acknowledge.
A DAIS server exposes many data objects. If authorization is supported, checks must be made by the server. The server must
then know who the operator is. An interface that can be used by the server to get this information is described in the Security
Service Specification [14]. The Security Service Specification includes a rich interface supporting extensive security comprising:
• Identification and authentication
• Authorization and access control
• Security auditing
• Security of communication
• Non-repudiation
• Administration
The smallest need for a DAIS server is to be able to identify an operator (a principal in Security language) so that access
control can be made from within the DAIS server. Authentication is assumed taken care of at the operating system login. The
control of access to a DAIS server itself within the scope of a secure system is not necessarily a requirement. The other
functions (auditing, secure communication, non-repudiation, and administration) supported by the Security Service are not
necessarily required for a DAIS server.