'Unhackable' data will go far

[R. A. Hettinga]

<http://www.electronicsnews.com.au/articles/a6/0c0196a6.asp>


Electronics  News 
September 16, 2003    

'Unhackable' data will go far 
By Andrew Woolls-King 
 
Long distance secure data transmission has moved a step closer with the transmission of quantum-encoded data over a distance of 100 km. Researchers claim that the breakthrough could make "unbreakable" secure data streams a reality within a few years. 

A team from Toshiba Research Europe, based in Cambridge, UK, has recently demonstrated a prototype system working over 100 km of fibre-optic cable. "As far as we are aware, this is the first demonstration of quantum cryptography over fibres longer than 100 kilometres," says Dr Andrew Shields, who leads the Toshiba group developing the system. "These developments mean that the technique could be deployed in commercial situations within three years." 

Early adopters include organizations that need to communicate highly sensitive data including banks, governments and legal firms. Yet with ever increasing numbers of companies falling foul to the malicious activities of hackers, it is likely that the market for viable quantum cryptography systems will be huge. 

Until now the biggest barrier to successfully using quantum cryptography has been reducing the amount of random noise picked up by the receiving detector (which can be positioned at either end of the fibre link) due to photon scattering out of the fibre. Indeed the rate of encrypted photons surviving the journey along long fibres was so low that they were masked by noise in the actual photon detector and the entire transmission process failed. 

But by developing an ultra low noise detector exploiting the latest semiconductor technology, the Toshiba team has managed to reduce this noise problem to a viable level for long distance transmission. Even if the 100-km distance can't be extended, some form of "quantum repeater" could be developed to enable totally secure communications over even longer distances. 

Quantum cryptography works by using the "teleportation" of quantum states from one place to another using photons as the communication "medium". In practice, two users on a fibre-optic network form a shared security key. The secrecy of the key is guaranteed by exploiting the wave/particle duality of light meaning that the key does not "exist" in any detectable sense until the photons sent from the transmitter actually reach the receiver. 

Although a hacker could conceivably intercept the stream of photons en route between the sender and receiver, Heisenburg's uncertainty principle dictates that that it is physically impossible to read the datastream without disturbing its quantum states and thus destroying the message. 

Current encryption approaches rely on algorithm that, no matter how complex, could eventually be cracked. With quantum cryptography security instead becomes an impenetrable and intrinsic part of the data itself. 


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R. A. Hettinga <mailto: rah at ibuc.com>
The Internet Bearer Underwriting Corporation <http://www.ibuc.com/>
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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