A
portable, versatile and low-cost molecular detection
tool being developed by a team of Computer code-makers
may soon get the upper hand on code-breakers thanks
to a new quantum cryptography method designed at
the University of Toronto. Quantum cryptography
uses particles of light to share secret encryption
keys relayed through fibre-optic communications.
A
paper published in the June 16 issue of the Physical
Review Letter demonstrates how senders can vary
the intensity of laser light particles (photons)
used in fibre-optic communications to create decoys
that catch eavesdropping attempts. "To exchange secret
communication, the sender and the recipient first
have to exchange a random series of 0s and 1s - known
as the encryption key - through a sequence of photons," says
the study's lead author Professor Hoi-Kwong Lo of
U of T's Department of Electrical and Computer Engineering
and Department of Physics. The security of the message
relies on the security of the encryption key. "If
an eavesdropper tries to intercept the transmission
of the encryption key, he will give himself away
by disturbing the photons. However, real-life light
sources occasionally send out more than one photon
and an eavesdropper can steal the additional pulse
without the sender knowing."
To
address this problem, Lo's technique manipulates
the laser to create different signals of various
intensities that act as decoys to distract the
eavesdropper from the secret message. "Any attack will necessarily
affect the decoy states and therefore be caught by
the legitimate users, who will then use an encryption
key only when it is guaranteed to be secure," says
Lo, who adds that the work has immediate commercial
applications.
The research was funded by the Canada Foundation
for Innovation, Canadian Institute for Photonic Innovations,
Canada Research Chairs program, Natural Sciences
and Engineering Research Council of Canada, Ontario
Innovation Trust and Premier's Research Excellence
Award.
CONTACT: Hoi-Kwong Lo, Department of Electrical
and Computer Engineering, 416-946-5525, hklo@comm.utoronto.ca,
or Karen Kelly, U of T Public Affairs, 416-978-6974,
k.kelly@utoronto.ca
|
