Even NSA has been working with Linux
From http://nsa.gov/selinux
"Linux was chosen as the platform for this work because its growing success and open development environment provided an opportunity to demonstrate that this functionality can be successful in a mainstream operating system and, at the same time, contribute to the security of a widely used system. Additionally, the integration of these security research results into Linux may encourage additional operating system security research that may lead to additional improvement in system security."
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Even NSA has been working with Linux From http://nsa.gov/selinux "Linux was chosen as the platform for this work because its growing success and open development environment provided an opportunity to demonstrate that this functionality can be successful in a mainstream operating system and, at the same time, contribute to the security of a widely used system. Additionally, the integration of these security research results into Linux may encourage additional operating system security research that may lead to additional improvement in system security."