Researchers unlock the key to `unbreakable' coded messages

R. A. Hettinga rah at
Thu May 13 08:43:02 EDT 2004


The Asahi Shimbun

 Researchers unlock the key to `unbreakable' coded messages

 TSUKUBA, Ibaraki Prefecture-The Holy Grail of data transmission-practical
communication of encrypted messages impervious to eavesdroppers-may finally
be within reach.

 On Wednesday, researchers at the National Institute of Advanced Industrial
Science and Technology here announced they had developed the world's
fastest quantum cryptography technology, which one day could be used to
transmit sensitive diplomatic, military and financial information requiring
the utmost confidentiality.

 Japanese, American and European companies have all been hard at work
trying to produce a quantum cryptography system that could quickly send
encrypted data over optical fiber cables.

 Encrypted information is already being transmitted over the Internet, but
the new technology would allow for the encryption ``key'' necessary to code
and decode the message to be supplied ahead of the message itself over
public channels.

 Akio Yoshizawa and his research team have developed a technology that puts
together the encryption key about 100 times faster than current methods.

 Until now, using quantum cryptography to send several pages of text
containing about 60 kilobytes of data over a distance of about 100
kilometers was a time-consuming endeavor.

 Although the encrypted document itself can be transmitted over the
Internet in a comparatively short period, it usually took about 13 hours to
produce the encryption key and transmit that safely to the receiver.

 Using the new technology, the key can be sent in only eight minutes.

 In making their key, Yoshizawa's team used a binary system for
representing the polarization of photons. Polarization refers to the angle
at which a photon vibrates.

 Any attempt by a hacker to eavesdrop on the encryption key disturbs the
photon's polarization and lets the receiver know that someone has attempted
to steal the key. Rather than allow the eavesdropper to steal the key, all
the sender and receiver have to do is agree on a new key for encrypting the
information to be sent. The key can be changed any number of times until
both parties are sure that it has not been tampered with before
transmitting the actual information in encrypted form.

 The technology, though, has a number of weaknesses. For example,
eavesdroppers aside, the photons have to be sent in such a way that they
will not be disturbed. Until now, this has meant that photons could only be
sent via optical fiber cable over short distances.

 The problem is, this method is susceptible to unwanted noise.

 However, Yoshizawa and his group have developed an optical detector that
can reduce the noise level over a 10.5-kilometer optical fiber cable. This
also reduces the transmission time.

 The new technology developed allows for the transmission of the key at 45
kilobits of data a second, or about 100 times current speeds.(IHT/Asahi:
May 13,2004) (05/13)

R. A. Hettinga <mailto: rah at>
The Internet Bearer Underwriting Corporation <>
44 Farquhar Street, Boston, MA 02131 USA
"... however it may deserve respect for its usefulness and antiquity,
[predicting the end of the world] has not been found agreeable to
experience." -- Edward Gibbon, 'Decline and Fall of the Roman Empire'

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