Full Disclosure mailing list archives
Re: Tempest today
From: "Bipin Gautam" <gautam.bipin () gmail com>
Date: Sun, 20 Aug 2006 05:34:09 +0545
Ok, here is something from the book that I was trying to assemble/write. Some Links: http://www.eskimo.com/~joelm/tempest.html http://www.erikyyy.de/tempest/ Lets begin… Faraday cages may be used to provide protection from HERF and EMP effects. Countermeasures: It is easy to defeat ordinary audio eavesdropping, just by sound-proofing a room. And simply drawing the curtains or creating a specially crafted background noise or by using double glass with air gap in the middle can soundproof and can defeat newer systems, which shine a laser beam onto a glass window and decode any modulation of the reflected beam caused by sound vibrations in the room. Faraday's cage: The charge on a charged conductor resided only on its exterior, and had no influence on anything enclosed within it. To demonstrate this fact he built a room coated with metal foil, and allowed high-voltage discharges from an electrostatic generator to strike the outside of the room. He used an electroscope to show that there was no electric charge present on the inside of the room's walls. A Faraday cage is best understood as an approximation to an ideal hollow conductor. A round drum, sphere etc can act like a Faraday's Cage. Basically, the enclosure may be made of an unbroken conducting sheet, like the metal box surrounding a sensitive radio receiver, or a wire mesh, like that in the door of a microwave oven. Any holes in the box or mesh must be significantly smaller than the wavelength of the radiation that is being kept out, or the enclosure will not effectively approximate an unbroken conducting surface. This shielding effect is used to eliminate electric fields within a volume, for example to protect electronic equipment from lightning strikes and other electrostatic discharges (ESDs). Faraday cages are often put to a dual purpose: to block electric fields, as explained above, and to block electromagnetic radiation. The latter application is known as RF shielding. Some traditional architectural materials act as Faraday shields in practice. These include plaster with wire mesh, and rebar concrete. These will affect the use of cordless phones and wireless networks inside buildings and houses. While Some buildings have designs that block radio signals by accident due to thick concrete walls or a steel skeleton. RF and Magnetic shielding: Radio frequency (or RF) shielding is required when it is necessary to block high frequency - 100 kilohertz and above - interference fields. These shields typically use copper, aluminum, galvanized steel, or conductive rubber, plastic or paints. These materials work at high frequencies by means of their high conductivity, and little or no magnetic permeability. Magnetic shields use their high permeability to attract magnetic fields and divert the magnetic energy through them. With proper construction, magnetic shielding alloys have the ability to function as broadband shields, shielding both rf and magnetic interference fields. Electromagnetic shielding: It is the process of limiting the coupling of an electromagnetic field between two locations. Typically it is applied to enclosures, separating electrical content from the outside world, and to cables, separating internal wires from the environment the cable runs through. The shielding is achieved using a conductive material as a barrier. Typical materials include sheet metal, metal mesh, ionized gas, plasma and aluminum foil. The shielding can reduce the coupling of radio waves, visible light, electromagnetic fields and electrostatic fields. The amount of reduction depends very much upon the material used, the method of connection of the shield (or screen) and the frequency of the fields of interest. One example is a coaxial cable, which has electromagnetic shielding in the form of a wire mesh surrounding an inner core conductor. The shielding impedes the escape of any signal from the core conductor, and also signals from being added to the core conductor. Though i have practically seen putting a dipole near the coaxial cable can sniff its signal within despite the sealing. The rf sealing strict depends on the quality which i've seen is rare in MOST commercial products for general uses. Shielded Tent: It Shielded enclosures, tempest equipment, shielded chambers Another way of making sure you are not being bugged is to use a shielded tent, which prevents radio waves entering or leaving. Though Mobile phone calls are impossible from inside the tent, but no-one will be able to listen to your conversations using bugs or radio wave listening devices. It will also prevent anyone intercepting radio emissions from computers, preventing them from seeing what you have on screen. A more sophisticated - and expensive - method is to build a "clean room", of the type used by the military, to shield radio waves and electromagnetic signals. Wireless Shielding Paint: A company, Force Field Wireless makes three products that it says can dramatically reduce the leakage of wireless signals from a room or building. The paint contains copper filings and an aluminum compound. When spread evenly on a wall, the paint reflects signals in frequencies from 100 MHz to 5 GHz. Paint four walls, a floor, and a ceiling, and you effectively have a Faraday cage, which is a specially constructed metal room that blocks all radio signals in or out. It also makes copper/aluminum powder that homeowners can add to their own paint. The company also makes a window film that cuts down on signal leakage. This product DefendAir would be an attractive option to protect an RFID-enabled warehouse. http://news.thomasnet.com/fullstory/459490/3280 Critic: Though wireless signals are very hard to completely block. They will simply radiate over and around obstacles. Metallic paint might reduce the signal strength, but that's easily compensated for by an antenna. Further-more its drawbacks are like it could reduce cellular reception. Any such technology won't block all signal - it won't block signal eminating from windows, doors, and screw holes. What it will do is lower the range from which you can sniff or connect, with constant equipment, which is plenty to be useful for some cases. Like a building situated near the center of a military base. Up to a quarterkilometer away is secured area. But obviously it will help you lower the sniffable range of the radiation to within that security perimeter and it's possible to arrange any conductive medium to actually amplify RF signals in a given direction You are quite likely to find a spot where the signal is considerably stronger.
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Current thread:
- Tempest today Paul Sebastian Ziegler (Aug 18)
- Re: Tempest today Joe Barr (Aug 18)
- Re: Tempest today Paul Sebastian Ziegler (Aug 18)
- Re: Tempest today J. Oquendo (Aug 18)
- Re: Tempest today Paul Sebastian Ziegler (Aug 18)
- Re: Tempest today Trey Keifer (Aug 18)
- Re: Tempest today K F (Aug 19)
- Re: Tempest today Bipin Gautam (Aug 19)
- RE: Tempest today Bill Stout (Aug 20)
- Re: Tempest today J. Oquendo (Aug 21)
- Re: Tempest today Michael Holstein (Aug 21)
- Re: Tempest today J. Oquendo (Aug 21)
- Re: Tempest today John Dietz (Aug 21)
- Re: Tempest today J. Oquendo (Aug 21)
- Re: Tempest today Joe Barr (Aug 18)
- <Possible follow-ups>
- RE: Tempest today Bryan_McAninch (Aug 18)
- Re: Tempest today Tonu Samuel (Aug 21)
- Re: Tempest today daylasoul (Aug 20)
- RE: Tempest today Lyal Collins (Aug 20)
- Re: Tempest today Marcin Owsiany (Aug 20)
- RE: Tempest today Lyal Collins (Aug 20)