Security unit and method for an industrial control system

A security unit for an industrial control system, comprising:

• an interface adapted to communicate with a plurality of components of an industrial control system via a data network;
• a security assignor adapted to access a first component among said plurality of components via said interface, and adapted to assign a first security level pertaining to said first component to said first component for storage of said first security level in said first component;
• said security assignor further adapted to access a second component among said plurality of components via said interface, and to assign a second security level pertaining to said second component to said second component for storage of said second security level in said second component, wherein said second component is different from said first component;
• wherein said security assignor is adapted to assign said first security level and said second security level to said first component and second component, respectively, in accordance with a system security level pertaining to said industrial control system;
• wherein said second security level is equal to said first security level;
• and
• wherein said security assignor is adapted to receive a message from said first component indicating that said first security level has been adopted by said first component, or cannot be adopted by said first component;
• and/or wherein said security assignor is adapted to receive a message from said second component indicating that said second security level has been adopted by said second component, or cannot be adopted by said second component.