Fiber Optics, as Never Been Seen

[InfoSec News <isn () c4i org>]

http://www.wired.com/news/technology/0,1282,50779,00.html

By Mark K. Anderson 
2:00 a.m. March 18, 2002 PST 

the idea of carrying phone conversations with light may date back to
1880, but its implementation took an entire century. It was only in
the 1980s that fiber optic channels were first integrated into
commercial phone networks.

In the intervening years, much has stayed the same -- scientists and
engineers still want to cram more and more zeroes and ones into those
familiar hair-thin wires of glass. But major advancements appear to be
on the way.

Next week, Anaheim, California, will host about 25,000 researchers as
they gather for the nation's leading fiber optics conference, the
Optical Fiber Communications Conference and Exhibit.

One of the more intriguing ideas to be presented involves using
chaotic behavior across fiber networks as a method of encryption.

According to Jia-ming Liu, professor of electrical engineering at
UCLA, the emerging field of chaotic communications offers new crypto
applications in both optical and wireless systems.

"I didn't invent this concept," he said. "But the entire field of
chaotic communication is pretty new."

His system, he said, starts with a laser that sends part of its beam
into photo detectors which produce electrical signal that feed back to
help power the laser. The resulting circuit behaves erratically --
something like the feedback you hear at a concert when the performer
wanders too close to his stack of amps.

Liu has found that if he picks his lasers carefully, he can set up two
such nonlinear (chaotic) circuits whose feedback behavior is the same.

Thus, if you have a message that needs to get from Albuquerque to
Boston without being snooped on, you place a laser in each city. After
the two lasers have been synchronized over an open channel, you add
your message signal on top of the sending chaotic laser. And once the
signal reaches Boston, you use the Boston laser to subtract off the
chaos -- and to get the original message.

"Any eavesdropper who tried to tap your message would just receive
noise -- akin to listening to static instead of the radio," he said.

On Thursday, Liu will report that his team has transmitted messages
using this chaotic crypto method at the benchmark speed of 2.5 Gbps --
also called the OC-48 level.

In fact, this speed is comparable to the rate that much non-encrypted,
long-distance telephone and Internet traffic travels at today.

"Today, most of the 'long-haul' traffic is either 2.5 or 10 gigabits
per second," said Ivan Kaminow, former senior science advisor at the
Optical Society of America. "A lot of research is now exploring 40
gigabits per second."

Indeed, one paper to be presented by a group from Agere Systems --
will be reporting a record-setting fiber optic transmission rate of
3.2 Tbps (trillion bits [terabits] per second).

Of course, fiber isn't the only potential bottleneck in the system.

Bishwaroop Ganguly of MIT is working on his PhD, examining the
interaction between the optical and the old-fashioned electronic
components in a network. On Wednesday, he'll be presenting work that
offers a new, more integrated model for conducting network traffic
with both optical and electronic signals.

Such a system, he said, could enable a best-of-both-worlds Internet --
in which the Net itself would intelligently switch between using
electronic switching systems for brief packets of data, such as Web
pages, while optical switches would handle the bigger chunks such as
MP3s or movie downloads.

"We're looking at more of a symbiotic relationship between electronic
sub-systems and optical sub-systems, where the electronics handle what
they're good at -- which is small transactions," he said.

"So consider a Web page. You wouldn't want to set up an optical
connection for each JPEG. But if you're transferring files from one
workstation to another, it would be nice if that could go all
optically and bypass the electronic routers."

Still, with all the applied and basic science being presented in
Anaheim, one basic question is still very much up in the air: Will
users see fiber optic lines coming into their home anytime soon?

Ganguly said his system is being designed mostly for businesses. But
he also said that it's a truism of the Internet that as bandwidth
increases for individual users, new applications always emerge to fill
it.

"The point is there are existing applications," he said. "But there's
another paradigm here too: Build it and they will come."



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