Date: Sun, 20 Aug 2006 01:44:42 -0500
From: <daylasoul@...h.com>
To: <full-disclosure@...ts.grok.org.uk>
Cc: 
Subject: Re: Tempest today

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On Sat, 19 Aug 2006 18:49:09 -0500 Bipin Gautam
<gautam.bipin@...il.com> wrote:
>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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