Secure operating systems
One use of the term refers to computer security technology to implement a secure operating system. Much of this technology is based on science in the 1980s developed and used to produce what some of the most impenetrable besturingssystemen ever. While still valid, the technology is in limited use today, especially since a number of changes in the management of the system imposes and also because not much understood. This ultra-strong secure operating systems are based on the operating system kernel technology that can guarantee that certain security policies are absolutely enforced in an operational environment. An example of such a computer security is the Bell-La Padula model. The strategy is based on a coupling of special microprocessor hardware features, often involving the memory management unit, special correctly implemented operating system kernel. This forms the basis for a veilig operating system, where certain key components are designed and correctly, the absolute impossibility of penetrating hostile van elementen guarantee. This capability is enabled because the configuration not only imposes a security policy, but in theory completely protects itself from corruption. Simple systems, on the other hand, not the features that assure you that this maximum level of security. The design methodology to produce such secure systems are accurate, deterministic and logical.

Systems are designed with a similar method with the state of the art [Clarification Needed] computer security although products using such security are not well known. In sharp contrast to most types of software, they meet specifications with verifiable certainty comparable to specifications for size, weight and strength. Secure operating systems designed this way are used primarily for national security information, to protect military secrets, and the data from the international financial institutions. These are very powerful security tools and very few secure operating systems are certified at the highest level (Orange Book A-1) to work on the scope of the "Top Secret" to "unclassified" (including Honeywell SCOMP , USAF SACDIN, NSA Blacker and Boeing MLS LAN.) The assurance of safety depends not only on the soundness of the draft strategy, but also to ensure the accuracy of performance, and therefore there are degrees of security force defined for COMPUSEC. The Common Criteria quantifies security strength of products in terms of two components, security functionality and assurance level (EAL, such as mirrors), and these are described in a Protection Profile for a Security Target and requirements for product descriptions. None of these ultra-high assurance secure general purpose operating systems are produced for decades or certified under Common Criteria.

In the United States usage, the term High Assurance usually suggests the system has appropriate security features that are robust enough to DoD and DOE to protect classified information out. Medium suggests that security can protect less valuable information, such as income tax information. Secure operating systems designed for medium robustness levels of security functionality and reliability to meet have seen wider use within both government and commercial markets. Medium robust systems may provide the same functions as a high security assurance secure operating systems, but doing so at a lower assurance level (such as Common Criteria EAL4 levels or EAL5). Lower levels mean we are less certain that the safety functions are performed flawlessly, and therefore less reliable. These systems can be found in use on web servers, guards, database servers and the management of hosts and are used not only to the data stored on these systems to protect, but also a high level of network and routing services.