Re: Bare fibers

At 11:52 AM 7/25/96 -0700, abostick@netcom.com (Alan Bostick) wrote:
>As has been mentioned earlier, all an attacker has to do is encourage
>some of the light to exit the fiber, by bending it, contacting it with
>a detector, etc.
>If the detector is sensitive enough, the loss induced by this is minimal.
>This sort of tapping is exactly the sort of thing quantum cryptography
>is supposed to prevent, or at least identify.  

So far, so good.

>Nothing short of quantum methods is going to spot the tap, 
>unless you happen to come across the tap by inspecting the entire
>length of the fiber.

Pressurized conduit is a favorite paranoid technique - if the 
Bad Guy cuts open the conduit to get at the fiber, your alarm
system notices the pressure drop and goes off.
For slightly less paranoid scenarios, you can use heavy narrow
conduit with epoxied joints, and the extra alarm wire or two
to help detect cutting.  For substantially more paranoid types,
you can always fill your conduit with some sort of flammable
substance that reats with air...

#			Thanks;  Bill
# Bill Stewart, +1-415-442-2215 stewarts@ix.netcom.com
# <A HREF="http://idiom.com/~wcs"> 
#			Dispel Authority!

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On Fri, 26 Jul 1996, Bill Stewart wrote:

> Pressurized conduit is a favorite paranoid technique - if the 
> Bad Guy cuts open the conduit to get at the fiber, your alarm
> system notices the pressure drop and goes off.
> For slightly less paranoid scenarios, you can use heavy narrow
> conduit with epoxied joints, and the extra alarm wire or two
> to help detect cutting.  For substantially more paranoid types,
> you can always fill your conduit with some sort of flammable
> substance that reats with air...

for that matter, string fibers in bundles as such
      _
    _/ \_
   / \_/ \
   \_/ \_/
   / \_/ \
   \_/ \_/
     \_/

where the middle one carries the real signal, and the outer ones cary fake
signals, and use them for interruption detection.

 --Deviant
Legalize free-enterprise murder: why should governments have all the fun?


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