An anonymous reader writes to mention that the Tokeneer research project has been released to the open source community by the US National Security Agency. The main goal of this project was to show how highly secure software can be developed cost-effectively. "Tokeneer has been written in SPARK Ada, a high level programming language designed for high-assurance applications. Originally a subset of the Ada language, it is designed in such a way that all SPARK programs are legal Ada programs. Ada is the natural choice for mission-critical, high-integrity systems due to its combination of flexibility, reliability and ease of use, and SPARK further adds a static verification toolset that combines depth, soundness, efficiency and formal guarantees."