At this week's annual meeting of the Optical Society of America in Rochester, N.Y., Bernard Wu and Evgenii Narimanov of Princeton University will present a method for transmitting secret messages over existing public fiber-optic networks, such as those operated by Internet service providers. This 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 usual form of encryption, in which computer software scrambles a message. Instead, it's a more hardware-oriented form of encryption--it uses the real-world properties of an optical-fiber network to cloak a message.

The sender transmits an optical signal that is so faint that 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.