[IP] BBC: * Quantum leap for secret codes *

[Dave Farber <dave@farber.net>]

------ Forwarded Message
From: bobr@bobrosenberg.phoenix.az.us
Date: Thu, 05 Jun 2003 06:36:23 -0700
To: dave@farber.net
Subject: BBC: * Quantum leap for secret codes *

Dave

Some IPer's may not yet have seen how close BBC says quantum cryptography
may 
be.

Bob

 * Quantum leap for secret codes *
British scientists are close to creating a system to keep data sent via the
net 
secure, using quantum physics.
Full story:
http://news.bbc.co.uk/go/em/-/1/hi/technology/2963138.stm

-- 
 
Bob Rosenberg

Quantum leap for secret codes
Within three years, companies could be using quantum cryptography to protect
sensitive messages.

British researchers say they are close to producing an off-the-shelf system
that exploits quantum physics to create a secure communications channel.

The system encodes bits of information on individual particles of light.

This week, the researchers demonstrated their system working over fibres 100
kilometres in length.

Key controls 

Secure ways of communicating are hugely important to companies as more
business is done via the net.

Contemporary encryption algorithms ensure sensitive data stays secret simply
because it takes so long to work out which mathematical key was used to
scramble the information.

But companies could soon be turning to quantum physics to help them swap the
keys they use to turn meaningful messages into scrambled characters.


"It is a radically different approach to computer security," said Andrew
Shields, leader of the Quantum Information Group at Toshiba's Cambridge lab
where the encryption system is being developed.

"Quantum cryptography allows users to swap a shared secret key that can be
used to encrypt messages or authenticate messages sent across the network,"
said Dr Shields. 

"We can absolutely guarantee that each key sent is secret," he said.

Quantum cryptography works by using particular properties of individual
particles of light, photons, to represent individual bits of information.

"The sender sends the photons in a particular state which determines whether
it is bit 0 or bit 1," said Dr Shields.

The system being developed by the Toshiba researchers can form keys at a
rate of up to 2 kilobits per second. Much higher bit rates will be possible
in the future. 

Companies were unlikely to use the system to transmit entire messages, said
Dr Shields, but it was perfect for sending the keys used to scramble and
unscramble messages.

Bits and PCs 

Dr Shields said photon physics meant eavesdroppers changed the properties of
any photons they intercepted. As a result, it became obvious if a message
had been read by anyone it was not meant for, he added.

"The critical part is that bits have to be encoded on single photons because
it is impossible to copy them. It gives them a way of testing whether
someone else has read their message."

Unfortunately, the delicate states of the photons used to represent bits
also mean that quantum cryptography can only work along unbroken, and
relatively short, fibre optic cables.

By contrast, data sent across nations and oceans travels via fibre optic
cables regularly broken by repeaters that boost signals to ensure they reach
their destination. 


Dr Shields' team have demonstrated quantum cryptography working over
distances of 100 km, which should be enough to cover large metropolitan
areas such as London and Tokyo.

Dr Shields said he expected the first users to be financial firms keen to
establish secure communication between different offices.

One weakness with the system was what happened to encryption keys once they
started to be used in the leaky, insecure computers many of us had on our
desks, said Dr Shields.

"There are other vulnerabilities in the system that's true," said Dr
Shields. "The key has to be used in the right way to ensure the security of
the entire system."

The Department of Trade and Industry has pledged cash to help the
researchers refine their work and bring commercial quantum cryptography
products to market.

Dr Shields said commercial products should be ready in three years' time.

The researchers will be making their work public at the Conference on Lasers
and Electro Optics being held in Baltimore this week.



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