Re: [PEN-TEST] How secure is an ISDN line? Fibre Optic TAPs

["van der Kooij, Hugo" <Hugo.van.der.Kooij () CAIW NL>]

On Tue, 24 Oct 2000, Talisker wrote:

> "OC-# - OC-1,2-48 etc.. Any fiber optic medium is going to require you to
> split the fiber itself at some point and redirect the signal into a third
> party tap. From there you will once again have to reconstruct the data
> stream from the multiplexed/frame encapsulated data within.. this applies to
> almost any type of carrier."

I just saw some mentioning of using quantum level signaling to prevent
taps. As at this level you can't inspect a signal without altering it. So
a good CRC check would notice tampering with the transmission.

You could do this basically with any signal and medium that requires that
you you get more then 50% of the output for the output to be identical to
the input. So as soon as someone taps in either the tap or original
receiver will get the reliable signal. The other one will not and will
receive errors. Combined with error handling and encryption this would
make even an accesable medium tamperproof.

I'm not sure this theory can be used in a practical form today. I do know
that the maths that go with it are beyond my grasp. The basics behind it
however sounded plausible.

But at this point I feel we may go beyond the scope of this mailinglist
with this thread.

Hugo.

--
Hugo van der Kooij; Oranje Nassaustraat 16; 3155 VJ  Maasland
hvdkooij () caiw nl     http://home.kabelfoon.nl/~hvdkooij/
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