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Newly Declassified Window Film Keeps Out Snoops
An anonymous reader writes to describe a newly declassified window film from CPFilms Inc. that could give war drivers fits. Scientific American has the story, which includes a rather dismissive comment by Bruce Schneier.
"Once manufactured under an exclusive contract with the US government, this recently declassified window film is now available to the public. But don't expect to see it on store shelves anytime soon. Currently, it's only available directly from the manufacturer, and at prices that will likely make it prohibitive for all but the wealthiest home owners.
The two-millimeter-thick coating can block Wi-Fi signals, cell phone transmissions, even the near-infrared, yet is almost transparent... It can keep signals in (preventing attempts to spy on electronic communications) or out, minimizing radio interference and even the fabled electronics-destroying electromagnetic pulse generated by a nuclear blast."
The more mass an object has (like several feet thick concreate) the more it absorbs the signal, thin walls and windows etc have very little mass and absorb very little signal, I'm guessing this film reflects rather then blocks signal, but then you need mesh in your walls to prevent leaks that way. All up nothing to see here...
Also, putting it under the "Windows" category is a terrible pun...
You should get rid of it anyway. http://people.csail.mit.edu/rahimi/helmet/
They can, but you can use foil there. In fact if you have a modern enough house it is likely to have foil in the external wall insulation. Same for the roof. It is also trivial to retrofit (you can just lay it under a plasterboard.
As a result the doors and the windows remain the sole way in and out for the radiowaves. While special films like the one described in the article can deliver a nearly perfect insulation, they are not necessary.
If what you are bothered about are script kiddies driving down the street (or in your neigbour's basement) or interference from your neigbour's AP standard K-glass (or similar IR reflective type) will do. In my previous company we did a survey prior to moving into a new office and the drops was by more than 30db in the 802.11b/g band (in layman terms from 95% "quality" to sub 5%). In fact the drop from K-glass was more than the drop through a concrete floor covered by a steel plated grounded raised floor.
Baker's Law: Misery no longer loves company. Nowadays it insists on it
http://www.sigsegv.cx/
A rebar wall makes a fairly good Faraday cage, but mostly only the pillars are rebar. Many recent office buildings have 100% glass walls. The film would work ok there. On a building with walls, then a lot of signal normally leaks through. Yes, the posters are right in that thicker walls tend to attenuate better but usually they are quite transparent to RF.
The thing is that at least one of the existing metallized films (3M, I think) used for solar attenuation is quite a good RF blocker. Mobiles certainly don't work through it.
See my journal, I write things there
Can't blame the editors. The claim regarding resistance to EMP is a direct quote from (the ad copy embedded in the middle of) TFA. Morever, what TFA has to say about the film and EMP is that it is "capable of minimizing radio interference and even...EMP." They don't say block it, they say minimize it. The effective frequency range of the film is 10 Hz. up to "just shy of visible light" so I'd say they at least have a shot at it.
Now, EMP is what, again? Oh, yeah, Electro-Magnetic Pulse. Put another way, a really, really strong blast of RF interference. Anything that can completely block cell phone and wifi signals will at least somewhat hold back EMP. TFA goes on to say that one of the things that makes the film so effective is that it's part of a completely package. The film is only one component of what you're buying. Sounds like they probably retrofit the building with some kind of Faraday cage-like gear.
EMP doesn't melt plastic, it fry's electronics. Well, if you were so close to the hypocenter that the EMP could melt a 2 mm plastic film on the window, that would be the least of your problems, because if you didn't get vaporized at about the same time, the shockwave that arrived shortly thereafter would blow you, the window, and maybe the wall to the other side of the room.
The EMP they are trying to guard against is the high air burst kind (think huge warhead detonated in LEO over the US east coast) which is intended to take down electrical grids, telephone networks, and as much of everything else electronic as it can. A lot of Soviet (and presumably now Russian) scenarios included such an air burst as an early shot. Get one of those in position undetected and detonate it and you're then in a position to do a couple of things, such as:
If you have your buildings protected to the best possible extent by EMP shielding such as that stuff, it might allow you to launch in such a scenario before the other side does. You'd pretty much have to, because the EMP would fry the recon sats that would normally tell you if they were launching or not. You'd have to assume they were.
Some simple, real basic cheap tests. He had various samples of the film.
Place it directly over a cell phone, and the signal disappears, for instance. Place it directly between a wireless router, and your wireless card, and you cease to get a signal.
He insisted he had seen proper rooms done up with the material when he met with the manufacturer, and you could maintain a network inside a building without signal loss, but it would block the signal from getting out.
We had worked together at a casino where they put 50 access points directly over the new table games section to put in their first ever wireless network. I was arguing that we didn't need 50 access points to cover a very small area, and also arguing the security holes this created, to which the executives said "we'll simply buy another $200,000 firewall to plug the wireless network into. That will make it secure!"
I kept explaining how I could sit the parking lot (or likely a few blocks away with those 50 access points (salesmen are always objective with how much you need to buy from them) and pick up the signal, and do all kinds of naughty things with it. No one listened, and the casino wasted their money on a very insecure system. My friend (who was then a manager in Slots) remembered all that, and when he discovered this film, he gave me a call and asked me to research it.
There is little to no information online about it, even though it has been around a long time. However, if I recall the manufacturer (assuming it is the same company in this article, which I can't pull up to the Slashdot effect) insists their product is in the Pentagon, the FBA, CIA, NSA, and all the three-letter agencies.
http://blindscribblings.com - Tasty pop-culture in conceptual fashion.
it also means that you obviously wont be using your cell phone inside the house, you'll still need to go outside
Not always. Once you have a sealed RF container, you have the choice of what to let in and what to keep out. For example an active Cell/Pager repeater will provide excelent phone and pager coverage in the building. WiFi would not be in the passband and wouldn't get through. If you need it, you can always install an outdoor WiFi antenna and firewall it from your indoor LAN. Now WiFi works, but protected from snoops looking for the secure side of the LAN.
The truth shall set you free!
If it were effective, it would still be classified.
. kaya-optics.com/images/kodak_1_s.jpg&imgrefurl=htt p://www.kaya-optics.com/products/applications.shtm l&h=142&w=118&sz=23&hl=en&start=4&tbnid=KD3TcOf3Id c-bM:&tbnh=94&tbnw=78&prev=/images%3Fq%3DIR%2Bphot os%2Bsunglasses%2Btinted%2Bwindow%26gbv%3D2%26svnu m%3D10%26hl%3Den
Not always. Many things that were classified are no longer classified because they became common knowledge and no longer required protection. Some examples are encryption standards, Nuclear basics, some radio modulation techniques, some CPU's, some radio frequencies, and much data from WWII. Even some of the SR71 information is no longer classified.
The fact a window tinting film can have a metalized film that blocks RF is now common knowledge. Others have stumbled upon the fact. Offices with metalic colors such as bronze, copper or stainless, have had problems with cell and pager coverage. GPS users have had reception problems in some vehicles. Many films are designed to reduce IR transmission to keep the heat out. With all that general knowledge, having a classified film with these properties is a moot point.
Just because it is declassified does not make it ineffective. The stealth fighter is still a low radar profile item.
It was classified when the film was used on the cockpit windows of stealth fighters to prevent radar reflections from entering the cockpit and having a retro-reflection back to the radar source. It's now common knowledge the stealth fighters have RF screens over things like Jet intakes and conductive films over windows so the plane's cavities do not reflect a signal back to the direction it came from. This lack of a reflection back to the source is what makes a stealth plane invisable to radar. Very little signal returns. All reflections are sent off to an angle, not back to the source. It's no longer a secret, so the film tech is now declassified.
If you don't want to spend big bucks for the official military product, visit your local car window tinting shop. Ask for a film that keeps out the heat and has a a nice metalic tint. Ask for samples. Take them outside and lay them on your GPS while watching signal strength. Pick from the ones that kill the GPS reception. Now you have one that blocks far IR, maybe near IR and radio. If you need to block near IR, take a IR modified webcam and see if it is transparant in the near IR. Most non-metalic window tints are water clear in the near IR. An IR camera sees through them like ordinary window glass.
Sample photos of IR and sunglasses and other materials. Caution, fabric photo may not be safe for work.
http://images.google.com/imgres?imgurl=http://www
The truth shall set you free!
they're illegal for good reason because they block emergency calls aswell :(. If only the ambulance service had a separate frequency
I was going to comment that there are already quite inexpensive and effective window films that block RF quite well.
That said, it seems that the big difference between them and this "declassified" one is that it seems to be optically transparent? If you don't need full optical transparency but a darkened tint is acceptable (probably not only acceptable but desirable in many office environments), metallized window tints such as even the cheapo ones sold as aftermarket automotive films will block RF quite well.
For optically transparent - the same conductive coating used for LCD screens would probably block RF well, but that isn't a flexible "add on" film and might be prohibitively expensive for building windows, even when compared to this new stuff.
If you don't need optical transparency, blocking RF is reasonably easy, at least for a building.
retrorocket.o not found, launch anyway?
Several places make "magenetic paint" you can buy it at home depot. Paint your outer walls and ground it (copper strip going to water pipe below painted over works great. (grounding leeches off EM fields so help reduce reflections and overall background noise.)
voila, no wifi or cellular.
Using a special expensive window film is silly, replace your screens with aluminum screens and magically they also no longer pass RF energy.
I get a kick out of all this "new" stuff coming out. Anyone that owns a home that was re-sided in the 70's and 80's typically has aluminum siding and aluminum screens and therefore is mostly living in a faraday cage. (except roof)
Most of the new metalized layers on new construction materials (if any is used) dont block RF worth a darn. I tried them all at new construction sites and none were as effective as good old aluminum sheeting and screening.
Do not look at laser with remaining good eye.
Good post on EMP, although I disagree on the vulnerability of military electronics and telecommunications to EMP.
EMP was a known threat during the cold war and military electronics were designed to withstand EMP.
I worked as a technician for AT&T Long Lines during the cold war and saw what was done in order to minimize the impact of EMP on the telephone facilities that were used by the military. As an example, the L-3 long haul coaxial cable system that went from Dranesville,VA and Waldorf, MD to Mojave, CA; with an L-1 spur to NORAD in Cheyenne Mountain, had tube type repeaters. Everything was heavily shielded and the facility offices and repeater manholes that were along the route were shielded underground buildings that were designed to withstand nuclear attack; including EMP. The buildings that housed AT&T AUTOVON military telephone system switches were also in those shielded underground buildings.
EMP was a MAJOR consideration and EMP resistance was built into electronic equipment and systems. I have a very difficult time believing that recon satellites were not designed with EMP resistance being a major priority.