HRU (security)

The HRU security model (Harrison, Ruzzo, Ullman model) is an operating system level computer security model which deals with the integrity of access rights in the system. The system is based around the idea of a finite set of procedures being available to edit the access rights of a subject $s$ on an object $o$ .

The model also discussed the possibilities and limitations of proving safety of systems (in the general case) using an algorithm.