Fiber Lines Are Handy Mode for Secret-Message Code
ROCHESTER, N.Y., Oct. 10 -- A new technique sends secret messages so cleverly it would impress James Bond -- and it requires no new equipment or infrastructure.
At the 90th annual meeting of the Optical Society of America, being held this week at the Rochester Convention Center, Bernard Wu and Evgenii Narimanov of Princeton University presented a method for transmitting secret messages over existing public fiber-optic networks, such as those operated by Internet service providers. The technique could immediately allow inexpensive, widespread and secure transmission of confidential and sensitive data by governments and businesses.
Wu and Narimanov's technique is not the familiar type of encryption in which computer software scrambles a message. It's a more hardware-oriented form of encryption that uses the real-world properties of an optical-fiber network to cloak a message. The sender transmits an optical signal that is so faint it is very hard to detect, let alone decode.
The method takes advantage of the fact that real-world fiber-optics systems inevitably have low levels of "noise" -- random jitters in the light waves that transmit information through the network. The new technique hides the secret message in this optical noise.
In the technique, the sender first translates the secret message into an ultrashort pulse of light. Then a commercially available optical CDMA (code division multiple access) encoder spreads the intense, short pulse into a long, faint stream of optical data so that the optical message is fainter than the noisy jitters in the fiber-optic network. The intended recipient decodes the message by interpreting information on how the secret message was originally spread out, using an optical device to compress the message back to its original state. The method is reportedly very secure: Even if eavesdroppers knew that a secret transmission was taking place, any slight imperfection in their knowledge of how the secret signal was spread out would make it too hard to isolate from the more intense public signal.
Although the researchers have made this transmission scheme public, and the components for carrying it out are all available, lead author Bernard Wu said he doesn't believe it is being used.
"As the method uses optical CDMA technology, which is still undergoing significant research, I don't think any government or corporation is implementing this technique yet," Wu says.
Wu said government and businesses would likely have the greatest need for the technique but that there are potential consumer applications, for example, for occasional online banking transactions.
"This would not be a primary transmission scheme one would employ 24/7, as the price for enhanced security is a lower transmission rate," said Wu. But since consumers send encrypted information to banks only intermittently, this "stealth method" is practical for that purpose, he said.
For more information, visit: www.osa.org/meetings/annual/
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