[time-nuts] Time security query

[Bill Hawkins]

Group,

The questions of network and radio security are being applied to industrial
control systems, which is my field of endeavor.

Control systems also require an accurate sense of time of day, to stamp the
time of events occurring in the controlled process. GPS is the preferred way
to get accurate time, even though process sensors seldom sample faster than
120 times per second. These time stamps are required by government
regulations
in some industries.

So, what are the threats to a GPS time receiver? Jamming is possible, or
just
overloading the receiver, but the receiver goes into holdover mode and keeps
on ticking with the disciplined oscillator. This does little damage compared
with jamming the transmissions of wireless sensors.

Spoofing the time from a remote location seems impossible. Or is it just
difficult? Security by obscurity is not secure. Continual time changes could
confuse a control system that had scheduled activities, as well as mess up
the trends and logs that record the history of the process.

Thanks for any comments I can pass on in a talk on this subject.

Bill Hawkins

Observation: Passwords are merely obscure.