Hi Spehro,

On 8/22/2014 1:00 PM, Spehro Pefhany wrote:
On Fri, 22 Aug 2014 11:20:23 -0700, Don wrote:

On 8/22/2014 6:26 AM, Michael A. Terrell wrote:

rickman wrote:

And they probably thought they had fixed the problem. All you need to
do is to apply something that is not so easily seen but easily removed
by touch. Then check it after the locks have been used, but before they
have been cleaned.

In a defense plant where you had to empty your pockets to get into
the building?

"Dust" from (unused) toilet paper; finely ground salt/sugar from
the cafeteria; thin film of soap (from bathroom sinks); etc.

Donut glaze perhaps.

Actually, take the *opposite* approach -- wipe the buttons impeccably
clean! Then, count on the oils from the user's fingertips to adhere
talc, graphite dust (pencil shavings), etc. to the buttons that have
been touched. (you wouldn't want to use graphite BEFOREhand as that
would leave the user wondering why his fingertips were grey...)

Security used in diamond mining is interesting.

I found casinos to be the *most* interesting. There, a strained
expectation of "proper/legal behavior" is in place -- yet you know
both sides distrust each other (and themselves!). And, adversaries
have a pretty good idea of the types of mechanisms that are employed
by the host -- so, already have had to "step up their game" beyond
that of simple/brute-force attacks.

Think of it... you have access by The General Public (not just a
set of pre-screened employees -- diamond miners in your example).
You can't realistically SEARCH each person entering/leaving the
premises (at least, not *visibly*!). And, you want folks to feel
WELCOME and WILLING TO LINGER. Couple that with the fact that
casinos are designed to be the main thoroughfare through the
facility:
- want to go to a show? you need to pass through the casino
- want to exit the building? proceed through the casino
- want to get something to eat? casino, again
etc.