Toward a Medium-Robustness Separation Kernel Protection Profile

A protection profile for high-robustness separation kernels has recently been validated and several implementations are under development. However, medium-robustness separation kernel development efforts have no protection profile, although the US Government has published guidance for authoring such a profile. As a step toward a protection profile, a set of security requirements for medium-robustness separation kernels is proposed. These requirements result from an informal, yet principled, approach. By bracketing the problem with appropriate reference points and elaborating a method for interpolating the requirements both a measure of uniformity and a basis for further discussion are achieved. Our reference points include the high robustness protection profile, the existing medium robustness consistency instruction, and our familiarity with the nuances of separation kernels. This practitioner-oriented study is intended to advance the prevailing practices for commercial software development, which presently falls far short of the rigor needed for either high-robustness or medium-robustness systems. These requirements represent an incremental improvement in the pursuit of secure software - and is intended to be a step forward on the road to higher assurance.