On Fri, 3 Jan 2003 07:24:12 +0100 (CET), you wrote:
We have a resourceful adversary, who will quickly learn the
tricks. We need a low-tech technology that will be highly resistant
against undetected tampering by the adversary.
Hindering the adversary is the fact that he must face thousands
of homebrew approaches, rather than simply discover once a means
of defeating the Mark 423 Mod 8 Closet Opening Detector.
Low tech is quite best. Using cameras and receivers that rely on
RF simply broadcasts the nature of the device. They are useful
primarily to distract from the real device. Likewise magnets
scattered about, and a few small lengths of wire connected to
light bulb filaments, or whatever.
Using devices based on storing evidence of incursion on the
diskdrive is overly complicated and easy to defeat. (A crash,
followed by auto-discovering of a bad sector, reboot, you are in
doubt, etc.)
You need to deal with radiographic analysis, expert
manipulation, micro-camera inspection, etc. You need to use what
you can find in a prison kitchen, for example. You need to be
able to make it with only implements and materials that a
prisoner might have access to. Hey, if you are going to be
paranoid
Assuming you want only to detect a door opening (not removal and
reinstallation of the wall opposite the door, etc.) here is a
nice low tech way.
Get a tablespoon of flour and dye it red with food coloring. Dry
it completely. Separately, dye another tablespoon of flour
orange and dry it.
Get a small clear plastic needle box or fishing lure box, and
sprinkle some of the orange flour onto the bottom of the box, in
the form of a set of digits, say 8 3 7. Now cover that up
completely with the red flour. Now the digits can only be seen
from the bottom of the box, and when the box is placed bottom
down on a piece of balsa, it is immune to radiographic viewing,
or micro camera viewing (more on this).
Superglue (or make glue from flour and water, if the warden
doesn't permit superglue) a thin paper hinge strip to the edge
of the piece of balsa (or several sheets of flat paper glued
together with flour-water glue) and superglue the other edge of
the strip to the inside opening edge of the closet door, using a
thin strip of paper as a hinge between the inside of the door
and the balsa shelf. Now you have a very small hinged shelf that
is hanging down, on which to place the needle box containing
your hidden flour digits, when the hinge is propped up in the
shelf position.
To prop the hinged shelf up so you can place the needle box on
it, go inside the closet and close the door. Now glue a
toothpick in the door facing on the inside of the closed door
that holds the shelf up. When the door is closed from the inside
and that toothpick is in place, the toothpic just barely
supports the rear edge of the hinged shelf. If the door were to
be opened a quarter inch, the shelf drops off the toothpick
supporting it, and the shelf drops, erasing the flour letters.
Now exit the closet, and use a dremel to drill a very small hole
in the closet door. If your warden doesn't allow dremels, use a
paperclip, or use a screw and screwdriver, or whatever. You have
time on your hands anyway, if you can't come up with a way to
drill a micro hole in a closet door, you have larger problems.
The position is just under the shelf.
Now to arm it. From the outside of the opened door, stick a
tooth pick into the hole in the door under the hinge, supporting
the shelf. Place the flour holding needle box on the shelf.
Close the door. Remove the toothpick from the outside of the
closed door. The hinged shelf drops slightly onto the facing-
mounted toothpick. It is armed. To open, insert the toothpick
into the hole from the outside of the door and open slowly.
Glue a medium size paper board box to the door facing, uncovered
on the side toward the closed door, so that the entire works has
freedom to operate, but is enclosed when the door is closed and
the shelf is armed. This protects from micro cameras.
Now drill several more holes in line with the real one. At the
inside of each of the dummy holes, link them using a popsicle
stick and toothpick linkage to a stick that pushes the toothpick
in the inside door facing slightly back, dropping the flour
needle box. Tamper detection, even if they don't open the door.
Write on a sheet of paper and super glue it over the outide of
the armed door over all the holes. That should show some crude
tampering and cover the holes from pre-cracking surveillance
expeditions. Alternatively, use thumbtacks or push pins in the
holes to display some ubiquitous prison regulations. If they
remove the regs, they expect to see the little holes in the
surface of the closet door. Make lots of such tack holes.
Now, they can't use radiography, there are no magnetic or metal
parts, they can't do micro camera analysis without robotic
disassembly, and even then
