In sci.electronics.repair Michael A. Terrell wrote:

Cydrome Leader wrote:

In sci.electronics.repair Michael A. Terrell wrote:

Cydrome Leader wrote:

In sci.electronics.repair Michael A. Terrell wrote:

Cydrome Leader wrote:

In sci.electronics.repair Michael A. Terrell wrote:

Cydrome Leader wrote:

In sci.electronics.repair Michael A. Terrell wrote:

Don Y wrote:

On 8/20/2014 9:21 AM, rickman wrote:
Most of the Kensington devices that I have seen are easily
thwarted (shims, picks, etc. -- e.g., a thin sheet of CARDBOARD,
fragment of a soda can, etc!).

I understand how ALL locks work: locks keep honest people honest.
Period.

All sorts of things are possible. A Kensington lock deters a large
percentage of would be thieves. It is a practical solution that provides
a reasonable amount of protection for a low price and a minimum
inconvenience. If you have a $1500 laptop and want to eliminate any
chance of it being stolen, you can always keep it in your safe deposit
box.

They keep folks who need a "gentle reminder" that "Thou Shalt Not Steal"
from stepping over the line. Most "protection devices" have obvious
flaws or simple exploits. E.g., many homes have sliding doors that
are installed improperly. Your neighbors won't exploit it to enter
your home while you are out -- but, a thief would be glad to do so!

Reasons/motivations for an actual "theft" vary.

When I was in school, picking locks was "just something you did".
No big deal.

A friend used to wander the basements of the school methodically
picking EVERY lock -- leaving the doors, etc. UNlocked when their
occupants arrived in the morning. To him, it was just "practice".

Apparently, one day, he decided to do more than just pick the locks,
no doubt encouraged by how *easy* it was. He was gone a few days
later.


They bragged about how secure the pushbutton locks were at a defense
plant where I worked. I laughed and told them they were useless. They
quoted the number of possible combinations. I shrugged, looked at the
lock, bunched five buttons and opened the door. They demanded to know
who gave me the combination. I smiled and told them, Your cleaning
service. I was told, in no uncertain terms that they were not given the
codes. Then I pointed out that they were not cleaning the face plates
so All I had to do was look at one of the locks to know the code. They
didn't believe me, so I walked down the hall, opening one restricted
area after another. The next day, the chrome bezels were clean and they
looked like they had been waxed. ;-)

simplex type locks are pretty hillarious, expecially when the codes can be
entered in any order, or just by hitting all the right buttons in any
order.


These had to be in the right order, but that was no problem since
each time someone pushed a button, they wiped some crud off their
fingertips. You just punched them in order of the descending crud.

One facility I worked at had some "Department of Defense" certifed keypads
(whatever that means, if anything at all, I was never told a certification
level of spec they adhered to) that were fairly smart.

The keypad had LED displays inside each swith position in the form or a
telephone keypad that could only be read at sitting in a wheelchair height
at which they were mounted. The digits at each button always changed so it
was not possible to watching somebody enter a code and then repeat it as
you could not see what they were keying in. Wear on the keypads was kept
even too, and funny business with figuring out which keys were pressed
last was useless.

Those got disconnected and they went back to keycards for some reason.


What years? Mine was mid '70s, and the DCAS inspector was one of the
group "I showed that flaw, that day.

The cool keypads were in place until maybe 2010? They looked old as heck
but were not all that old when they were installed less than 10 years
before.

That's a couple generations newer that what we had.

I can't imagine they changed much over time. I'm not sure how they were
wired back to a controller. RS-422 maybe?


From mechanical, to electronic. Either that or RS-485.

So the funky keypards are properly called "scramble keypads" or "scrable
pads". Schlage bought somebody that made them and it looks like Hirsch
also makes them too.