I described a IR-only retroreflector that doesn't need any on-board power in
the searched-for device.
If you want some sort of control by the searcher, why not use something like
using an infrared remote-controller to activate a sensor on a hidden, but
visible package?
https://www.futureelectronics.com/c/semiconductors/optoelectronics--infrared-receivers/products
You can see these devices from the manufacturer Everlight, which could be
installed on the searched-for device: (Ordinarily, these devices are
installed in TV's and other remote-controllable devices.
https://www.futureelectronics.com/c/semiconductors/optoelectronics--infrared-receivers/products?selectedTab=products&q=%3Arelevence:manufacturerName:Everlight&text=
One consumes 0.4 milliamp at 2.7 to 5.4 volts DC. Two AAA alkalines, from the
Dollar Store, costs 50 cents, and probably has a capacity of 1000
milliamp-hour.
EAIRMIA1
Everlight 38 KHz 6 V 8 m SMT Top View Infrared Receiver Control Receiver
Module 2.7V to 5.5V
So, such a battery would keep the searched-for system alive for over 2000
hours. I don't know the details of how you could specially-code the
transmitter and receiver to include a secret unlock-code.
I believe that some of these new IR controllers may have an IR back-channel
from the TV to the controller, but I know little about that.
One solution would be to use a commonly-available remote control, say an
Comcast/Xfinity controller, and design a replacement internal PCB to entirely
change the functions. If you've ever looked at one of these remote
controllers, you will see that virtually the only 'smarts' on them is a single
tiny IC, which does all of the keyboard scanning, and drives the IR LED
included in the hardware.
However, the simplest technique would be something like using the smarts in the
existing controller to program a relatively-long code, say 6 to 9 digits, so
that the searched-for device will only respond to such a custom-programmed
remote controller device. A little research will probably provide that
information.
Jim Bell
On Monday, January 14, 2019, 4:49:50 PM PST, Steven Schear
<[email protected]> wrote:
The cryptographic artifacts are currently based on inexpensive, off-the-shelf,
devices. The passive WiFi mode is ingenious. One problem, AFAIK, with the
commercial devices I found is the absence if a RTC (I think these can be
soldered, carefully, onto the PCB) without which power consumption if too high
and standby times too short.
As for LiFi, the commercial technologies have been focused on visible light
frequencies (so as to combine lighting and communications in one device). If
LEDs were developed emitting in ozone absorption bands they could operate in
sunlight, something current LiFi cannot.
On Sun, Jan 13, 2019 at 11:46 PM jim bell <[email protected]> wrote:
On Sunday, January 13, 2019, 7:44:21 PM PST, Mirimir <[email protected]>
wrote:
Dropgangs, or the future of dark markets
https://opaque.link/post/dropgang/
>Nice. It's cool to see serious tradecraft applied to this stuff.
Especially compartmentalization.
>And yes, using traditional shipping systems is a serious problem for
old-school dark markets. I've thought off and on for several years about
the potential for using dead drops with accurate GPS. I mean,
geocaching. Many years ago, when I was dealing LSD, it was pretty common
to use dead drops. But then, they were typically rental lockers in bus
and train stations.
>I agree that ubiquitous surveillance is a problem. However, it's
~clueless customers and low-level distributors who'll most likely get
pwned. And they won't know anything importnt about the operation overall.
Yes, I am also quite impressed at the amount of thought that has been put into
this concept, see the link above. I would be quite interested in helping in
designing these systems, as I have been following some of the necessary
technologies for years.
I foresee a stiff plastic or metal pipe, tapered to a point at one end, which
can be driven by force into soil or into a lawn, so that it ends up to be
approximately flush with the plane of the soil. Once placed, a smaller
cylindrical container, as well as active elements, if needed, can be slid into
the metal pipe, from above.
>From the linked article: https://opaque.link/post/dropgang/
"This challenge is met by Dropgangs in various ways. The primary one is that
the documentation of each dead drop is conducted in minute detail, covering GPS
coordinates, photos of the surrounding and the location, as well as photos of
the concealment device in which the product is hidden (such as an empty coke
can). The documentation however increases the risk for the Dropgang since
whoever creates it would be more easy to identify by surveillance. In addition,
even great documentation still requires the customer to understand it and
follow it precisely, which can lead to suspicious behavior around the dead drop
location (staring at photos, visually comparing them to the surrounding, etc)."
[end of partial quote]
Ordinarily, smartphones that use GPS, don't use accurizing features, such as
WAAS. (Wide Area Augmentation System).
See https://en.wikipedia.org/wiki/Wide_Area_Augmentation_System
WAAS correction data is probably already available on the Internet.
"Accuracy[edit]
The WAAS specification requires it to provide a position accuracy of 7.6 metres
(25 ft) or less (for both lateral and vertical measurements), at least 95% of
the time.[2] Actual performance measurements of the system at specific
locations have shown it typically provides better than 1.0 metre (3 ft 3 in)
laterally and 1.5 metres (4 ft 11 in) vertically throughout most of the
contiguous United States and large parts of Canada and Alaska.[3] With these
results, WAAS is capable of achieving the required Category I precision
approach accuracy of 16 metres (52 ft) laterally and 4.0 metres (13.1 ft)
vertically. [end of partial quote]
WAAS might be described as a form of differential GPS. If the location as
computed by the smartphone was improved by WAAS, the statement above indicates
an accuracy within about 1 meter.
IR-specific retroreflectors to greatly simplify things.
The article describes complicated systems using Bluetooth or WiFi to help
locate these dead-drops. While they are certainly innovative, they add cost
and complexity to the hardware involved. I have thought of a much-cheaper
system that I feel is sufficiently secure and simple for common use.
Light-retroreflectors are commonly made from Scotchlite
https://en.wikipedia.org/wiki/Retroreflective_sheeting or plastic molded
corner-cubes. If a rather small (say, 1/4 in diameter) sphere covered
with retroreflector material was held up from the insert, possibly by a short,
thin stiff wire, the sphere could be visible, but not excessively obvious even
during the daylight. It would be easy to find this device with a flashlight
in the dark. For added security, an infrared-transmitting plastic (such as is
often used to cover IR-activating remote controls, such as
https://www.eplastics.com/plexiglass/acrylic-sheets/ir-transmitting )
could be used to ensure that only IR is retroreflected back to a searcher.
Ordinary smart-phone camera arrays are not only sensitive to human-visible
light (generally described as 400-700 nanometer wavelength), but are also
sensitive to near-IR wavelengths. If a smartphone camera was combined with a
directional IR LED, substituting for the white light LED lamp used for
photography, and aiming in the same direction, a user would be able to see
(through the camera display) the IR-specific reflections from an IR-limited
retroreflector, and this would probably be doable both during the day and at
night. A person operating such a camera would "look like" he was doing
photography, or perhaps playing a game. Somebody watching, even at night,
could not see the IR. The IR 'searchlight' could be a narrow-beam device,
perhaps with a full-angle of 16 degrees or so (typical for a narrow-beam IR
LED), so it wouldn't be particularly obvious even if watched through an IR
viewer. (If the IR LED itself was shielded from direct view.)
One advantage of this technique is that the searcher could identify the target
from a very long distance away, perhaps many tens of meters, and thus approach
it in a more "innocent" fashion. No obvious "searching" would have to be
performed in the open. And, the person who placed the dead drop could
ascertain its status without later needing to approach it closely.
This technique could be combined with Bluetooth or WiFi techniques, too. The
retroreflector could normally be retracted, and only raised if the proper
Bluetooth or WiFi signal was heard. Or, perhaps, the target would contain an
exposed IR LED, which would activate from an battery only if the proper
signals were heard. The resulting dead-drop would be virtually impossible to
find.
Jim Bell
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