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View Full Version : Anti-Wi-Fi paint keeps your wireless signal to yourself


Æhµ
2nd October 2009, 10:29 PM
http://tech.yahoo.com/blogs/null/151779

Don't like the idea of your neighbors rudely snooping on the wireless signal you slaved to pay for from the lazy comfort of their living room? It's not just about slowing down your connection; while they're downloading Mad Men via bittorrent, you could be on the hook for their actions.

Wireless security and encryption systems are fraught with problems and insecurity, and other methods to restrict your signal to a small area are cumbersome at best.

Enter a new solution: Anti-Wi-Fi paint.

The idea is simple: Use a special paint on walls where you don't want wireless to pass through (say the exterior of your house). The secret is mixing aluminum-iron oxide particles in with the paint. The metal particles resonate at the same frequency as Wi-Fi and other radio waves, so signals can't pass through the thin layer of pigment. Outsiders would simply be unable to access your wireless network, just as you, inside the house, won't be able to interlope on anything beamed on the outside.

Developed by the University of Tokyo, the paint is said to be the first that can block radio frequency in higher spectra where Wi-Fi and other higher-bandwidth communications occur rather than just low-frequency wireless like FM radio. Most Wi-Fi technologies operate at 2.4GHz; the Tokyo paint can reportedly block frequencies all the way up to 100GHz, with a 200GHz-blocking paint now in the works.

The paint isn't just of interest to those concerned about wireless leaking out of the building. Movie theaters have long been interested in finding a legal way to keep cell phones silent during screenings. Electronic jammers that actively block wireless signals are illegal, but passive materials that prevent wireless signals from getting through are not. Since the wireless-blocking paint can also block the lower-frequency signals that cell phones use, addled mobile junkies would have no outlet for reaching the outside world.

Some aren't convinced that anti-Wi-Fi paint makes a lot of sense for a secure situation, though. Says one engineer, "Surely the thought of having to redecorate a building in order to provide Wi-Fi security is more costly and complex than the security functionality available in even the cheapest of Wi-Fi access points..."

One more tool for keeping out the government snoops

odin_dax
2nd October 2009, 11:52 PM
What about windows? Do they suggest painting those?

Government snoops don't need to intercept Wi-Fi. I'm quite sure they can intercept data from the line, if need be, and I'm quite sure they have more experience with hard lines than Wi-Fi.

XnbX
3rd October 2009, 03:56 PM
What about windows? Do they suggest painting those?

Government snoops don't need to intercept Wi-Fi. I'm quite sure they can intercept data from the line, if need be, and I'm quite sure they have more experience with hard lines than Wi-Fi.

If I recall correctly there is a adhesive see trough thing for your window's.

Æhµ
3rd October 2009, 06:35 PM
This product ought to make for an easy way to construct your very own faraday cage, use it for your chop shop to block those gps units and lojacks, use it for stashing all those stolen ATMs, the possibilities are endless.

I'd love to be an advertising copywriter for this.


On a related note, have you ever heard of "chaff"? Those are typically thin strips of aluminum, the length being equal to one wavelength of an enemies radar frequency (in WWII it was one-half wavelength or one-quarter wavelength). When ejected by a plane, chaff will resonate to the frequency of the radar and "re-radiate" the signal. (my source is http://en.wikipedia.org/wiki/Chaff_%28radar_countermeasure%29 )

In WWII the radar being used typically had a wavelength of 27cm, and using multiples (or even fractions) of that length would cause the strip to resonate. Perhaps in this paint, they are using metal strips based on the wavelength of 2.4gHz (most common for wi-fi and cell phones)? The formula for frequency wavelength is below:

Speed of light / by Frequency = Wavelength in Meters (0.3 is the speed of light in air).

0.3 / 2.4gHz = 0.125 meters (12.5cm)
Still seems to long to use in paint, maybe they used a 1/4 wavelength?
Divide by 4 to get 1/4 wave = 31.25mm

For higher freqs like 5.8gHz it would be 12.9mm, and for 9.8gHz, 7.81mm. Notice 9.6 itself is a multiple of 2.4, so the 31.25mm strips will also resonate for the 9.6gHz freqs, but it's not as strong (there's all kinds of harmonics going on).

Still these strips seem a bit long for embedding in paint, oh well, guess they used some other means to resonate with those frequencies (the article did mention using "particles" in their paint)


But there might be something to all this chaff business, maybe this would be the way to build your Faraday cage to block a wide range of signals (and it might be stronger than the paint) -

* Buy/make "chaff" in lengths designed to resonate with the range of frequencies used in common communication devices, 900mHz, 1.2gHz, 2.4, 5.8, 9.6, etc.

* Use a sprayer and adhesive glues to spray this chaff over the walls of your "lair" (or whatever you have). Don't be stingy, the more layers of chaff the better.

* The glue should act as an insulator to prevent strips from being "shorted" (if two strips overlap, it will be like placing a finger in the middle of a guitar string, it changes the frequency it resonates at).

* Now that your walls are a mess of aluminum strips and spray glue, just seal it all up under a new layer of drywall or paneling. No windows allowed. The door itself can also be sprayed and paneled. You can even create a "lock" or vestibule type entry to ensure no signals leak out.

* Top it all off with a coat of that paint.

Now that should give you a good solid Faraday cage. I think.

Micro
4th October 2009, 03:01 PM
The chaff was meant to fool the radar and more commonly today, the radar of a anti-air missile system.
It does not block the radiation, it just looks like a object in the radar.

If you want anti WiFi via aluminum foil, pad the room with it.

Æhµ
5th October 2009, 12:35 AM
No it doesn't block it, but it "re-radiates" it. I guess that means a small cloud of chaff would paint a much bigger radar return than if were just

So you think that means a wifi, gps, or cell phone signal would still get through?

Maybe just better to stick with technology to block signals.

http://www.endoacustica.com/jammers_en_pag2.htm

XnbX
5th October 2009, 10:52 AM
J/K: In the near future al schools will paint their walls with this paint so the kiddies can't use their mobile's.
And what if you only paint one wall? Will the paint than act as a giant reflector/ booster?

TedB
5th October 2009, 11:29 PM
I found it partially ironic that the paint is made up of the same two elements/compounds that Thermite is made up of.

This paint will deter Wi-Fi 'thieves', but Feds, forget it.

Government snoops don't need to intercept Wi-Fi. I'm quite sure they can intercept data from the line, if need be, and I'm quite sure they have more experience with hard lines than Wi-Fi.

Exactly, Odin.

As I've already said before the safest way of doing things is protecting yourself at the PC's end.

All traffic originating from you... Proxy that shit.

Don't use a HD installed OS. A Live Disk is the way to go. Once the PC is off the session never happened. Using a HD installed OS leaves you susceptible to being proven guilty by Fed PC forensics.

davey_crockshit
10th October 2009, 09:31 PM
absorbs and damps out the signals kind of like the coating on stealth bombers. the chaff approach would give you weird multipath type interference probably. tinfoil under the wallpaper would be the better and cheaper approach.

But yeah, the feds would intercept your communications further up the line.