Optical nets easier to hack than copper

Optical nets easier to hack than copper
Optical nets easier to hack than copper 

By Bryan Betts
27 April 2007

Optical fibre is a lot easier to tap than most people imagine. There is 
no need to break or splice the fibre now - a relatively shallow bend can 
be enough.

The technique works because the light in the cable propagates by 
bouncing off the insides of the fibre. Unsheath the cable, and a 
detector can pick up the tiny amount of light that escapes through the 
fibre's coating, explained Thomas Meier, the CEO of Swiss company 

He demonstrated the technique on a fibre carrying a VoIP phone call over 
Gigabit Ethernet. A section of fibre from inside a junction box was 
looped into a photodetector called a bend coupler, and the call was 
recorded and then played back on a laptop.

"People claim optical fibre is harder to tap than copper, but the 
opposite is true - you don't even have to break the insulation, as you 
would with copper," Meier said. "You can read through the fibre's 
cladding with as little as half a dB signal loss."

He claimed that suitable bend couplers can be bought off the shelf - or 
from eBay - for a few hundred dollars, and connected to the extra fibre 
that is typically left coiled up in junctions boxes for future splicing 

The demo was to promote Infoguard's encryption devices which it said are 
10Gig-capable with a latency of just 5us. The Eur 29,000 (20,000) boxes 
encrypt at the network level, Layer 1, so are suitable for 
point-to-point links only, but Meier said that it means they can encode 
any protocol, not just IP.

He added that the risk is not imaginary or theoretical - optical taps 
have been found on police networks in the Netherlands and Germany, and 
the FBI investigated one discovered on Verizon's network in the US. 
Networks used by UK and French pharmaceutical companies have also been 
attacked, probably for industrial espionage, he said. 

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