security, standard A standard from the US Government
U.S. National Security Agency), "Trusted Computer System
Evaluation Criteria, DOD standard 5200.28-STD, December 1985"
which defines criteria for trusted computer products. There
are four levels, A, B, C, and D. Each level adds more
features and requirements.
D is a non-secure system.
C1 requires user log-on, but allows
group ID.
C2 requires individual log-on with password and an audit
mechanism. (Most
Unix implementations are roughly C1, and
can be upgraded to about C2 without excessive pain).
Levels B and A provide mandatory control. Access is based on
standard Department of Defense clearances.
B1 requires DOD clearance levels.
B2 guarantees the path between the user and the security
system and provides assurances that the system can be tested
and clearances cannot be downgraded.
B3 requires that the system is characterised by a mathematical
model that must be viable.
A1 requires a system characterized by a mathematical model
that can be proven.
(1997-01-09)