"The problem is innately difficult because from the
beginning (ENIAC, 1944), due to the high cost of
components, computers were built to share resources
(memory, processors, buses, etc.). If you look for a
one-word synopsis of computer design philosophy, it
was and is SHARING. In the security realm, the one
word synopsis is SEPARATION: keeping the bad
guys away from the good guys’ stuff!"

"So today, making a computer secure requires
imposing a “separation paradigm” on top of an
architecture built to share. That is tough! Even when
partially successful, the residual problem is going to
be covert channels. We really need to focus on
making a secure computer, not on making a computer
secure – the point of view changes your beginning
assumptions and requirements!"

-Brian Snow, NSA Technical Director