Verifiable secure operating system software

While the desire for reliable security in multiuser computer systems has grown significantly, the computing community's knowledge of how to provide the requisite protection is still inadequate. Security is a "weak link" phenomenon; one link whose condition is unsatisfactory is the operating system software. It has often been pointed out that currently "no protection system implementation of any major multiuser computer system is known to have withstood serious attempts at circumvention by determined and skilled users." The community is replete with apocryphal claims of secure systems that inevitably have failed.