Patent ID: 8468344

Claim:
A system comprising: a first computer system having one or more processors, wherein the first computer system is, by itself, natively operable only at a single security level and does not natively comprise a trusted computing base (TCB); an external, computer-readable mass storage device operable to be coupled to the first computer system, wherein the external, computer-readable mass storage device is not itself natively part of the first computer system, the external, computer-readable mass storage device comprising: a base operating system operable to be executed by the one or more processors of the first computer system, the base operating system configured to be bootable by the first computer system, the base operating system natively operable to implement only a single security level; a virtual operating system operable to be executed by base operating system being executed by the one or more processors of the first computer system, the virtual operating system executed using a virtualization tool executed by the base operating system, the virtual operating system operable to: implement a multi-level security (MLS) architecture usable by the first computer system; incorporate the TCB, wherein when the one or more processors of the first computer system execute the virtual operating system, the first computer system is operable to implement the MLS architecture in accordance with the TCB; process information, using the MLS architecture, according to a plurality of security levels, wherein the plurality of security levels comprises at least a second security level different than the first security level; and communicate at least a portion of the information processed according to the plurality of security levels from the first computer system to at least a second computer system distinct from the first computer system, the information communicated according to the plurality of security levels of the information; and an MLS gateway device in operable communication with the first computer system and with at least one security domain separate from the first computer system, the at least one security domain implementing the MLS architecture, wherein: a plurality of common levels of security are enforced by the first computing system when it executes the virtual operating system; the plurality of common security levels are enforced by a third computing system disposed within the at least one security domain; and the first computing system and the third computing system are operable to communicate with each other, using the MLS gateway, according to the plurality of common security levels.