Trusted operating systems (TOS) are
|“||security-modified or -enhanced OSs that include additional security mechanisms not found in most general-purpose OSs.||”|
"They were originally created to meet the need of the Federal government for high security mandatory access control (MAC) systems. TOSs provide a very secure system-wide control policy, a finely defined set of access privileges, and extensive logging and auditing capabilities. Many TOSs are independently verified to ensure that they meet the requirements set forth in their design documentation.
"TOSs are generally used in applications for which security is paramount. TOSs can securely control all aspects of a computing environment, including networking resources, users, processes, and memory. Specifically, TOSs can limit access to system resources in a manner that is not likely to be interfered with or compromised."