Using Chaotic Lasers to Encrypt Data
Encryption, typically accomplished using software, is one of the most widely used approaches to protecting data. Now, Spanish researchers have demonstrated a way to "encrypt" information sent over fiber-optic lines by slipping data streams into a laser beam that emits chaotically fluctuating signals.
The fluctuating signals hide data streams and make them very difficult for hackers to read, according to lead researcher Claudio Mirasso, assistant professor at Spain's University of the Balearic Islands.
This system uses a semiconductor laser. A mirror reinjects part of the device's initial signal back into the laser cavity, generating a new signal that erratically fluctuates in amplitude. A modulator or coupler then inserts a message into the new stream.
A new research system uses lasers to encrypt messages. A mirror reinjects part of the sending laser's initial signal back into the device's internal cavity, generating a new signal that chaotically fluctuates in amplitude. A modulator or coupler then injects a message into the new stream, which is all but unreadable if intercepted. The sending laser also transmits part of its initial signal into the intended receiving laser, allowing the latter to generate the identical chaotic signals. When the receiver gets the incoming stream, it filters out the chaotic signal, yielding the original message. The receiving laser must be made from the same wafer and must be nearly identical in other respects—with a maximum mismatch of 5 percent in terms of factors such as feedback strength and current bias—to the sending device, according to Mirasso.
The sending laser transmits the same part of the initial signal it used to create its chaotic stream into the receiving laser, allowing the latter to generate identical chaotic signals.
When the receiver then gets the incoming stream, it uses a chaos-pass filter to subtract the chaotic signal, thereby yielding the original message.
Mirasso said his team showed that chaotic lasers can send and receive a message over 120 kilometers of commercially laid fiber optics and can transmit encrypted data optimally and with low error rates at 1 gigabyte per second, comparable to that of most commercial fiber-based data transmissions.
To break the system, a hacker would need a receiving laser that is almost identical to the emitting laser or would have to intercept the data stream and reconstruct the transmitter's chaotic signal, both of which are extremely unlikely, Mirasso explained.
The researchers, who are continuing their work, haven't yet quantified the level of security they can offer but are working on this task. They say their encryption method might be ready for commercial use within 10 years.
Chaotic encryption has been studied before, Mirasso said, but his team's work "is the first field experiment under real-world conditions and using off-the-shelf fiber-optic components."
"You have to ask whether this funky laser scheme really adds anything to traditional encryption algorithms," stated Rice University assistant professor Dan S. Wallach, "or whether it's just a replacement for traditional cryptography and as such isn't really solving a problem."
Mirasso said his team's technique could complement software encryption techniques and offer a second level of security.
DNA Computer Is a Tic-Tac-Toe Champ
US researchers have developed a DNA computer that can perform the calculations necessary to successfully play the game tic-tac-toe.
The MAYA-II computer, which Columbia University and University of New Mexico scientists built, uses logic gates, inputs, and outputs made from a single strand of synthetic DNA. Each logic gate is between 55 and 100 nucleotides long. (A nucleotide is DNA's basic structural unit.)
One set of DNA strands, serving as inputs, acts on the logic gates, which are sets of DNA enzymes, explained Joanne Macdonald, associate research scientist at the Division of Experimental Therapeutics in Columbia University's Department of Medicine. This process then generates other DNA groups as outputs.
The MAYA-II always makes the first tic-tac-toe move, in the nine-square board's center box. To play the rest of the game, the computer and its opponents work with eight wells, representing the board's outer eight squares.
The machine uses 128 DNA logic gates, located in a buffering solution throughout the eight outer wells, to analyze its opponents' moves and calculate its best response.
To play the game, humans make their moves by choosing from 32 possible nucleotide input sequences and physically adding them to each well, said Macdonald.
To counter each of the opponent's moves, she explained, the MAYA-II chooses from responses preprogrammed into the logic gates. This guarantees the computer will win or tie.
The system labels outputs with fluorescent dyes. The game board uses a fluorescence plate reader to activate the dye and make the players' moves visible: humans' moves in green, the computer's moves in red.
Because MAYA-II involves biochemical processes yielding results that must be amplified for humans to see, playing a game takes a long time, with each of the eight moves taking up to 30 minutes.
Because DNA computing is molecular in scale, the technology could miniaturize computation, allowing, for example, trillions of molecules to compute in parallel in only a few microliters of solution, Macdonald explained.
Coupling the miniaturization with DNA's biological compatibility provides enormous potential for the development of biocomputers that operate within the body. This could lead to complex devices such as ones that could detect low blood glucose levels and trigger an insulin release. Macdonald said MAYA-II indicates such devices are feasible.
The MAYA-II researchers say their design should be particularly useful for refining techniques that analyze DNA samples and identify the genetic markers associated with certain diseases.
Some simple genetic screening and typing using DNA computation could be ready for implementation within a year or two, with biological computers requiring another five to 10 years, according to Macdonald.
"The novelty of MAYA-II is in the way it uses deoxyribozymes in logic gates," said professor Mitsunori Ogihara, chair of the University of Rochester's Department of Computer Science. "The system also uses two-color coding of the output from the gates to make detection easier, which is neat."
Nokia Has New Wireless Approach
Nokia has developed a small-footprint, energy-efficient, short-range wireless technology that could be used in devices such as health monitors, toys, computer mice, keyboards, and even wristwatches.
The company's Wibree technology would be used with embedded applications that make and receive infrequent small data transfers, according to Harri Tulimaa, Nokia's head of technology out-licensing. Wibree would be best suited for the type of energy-efficient, small-footprint applications required by inexpensive devices with minimal resources, he said.
Wibree, implemented via a chip, is radio-based technology. It operates in the globally available 2.4-GHz frequency band currently used by Bluetooth, another short-range wireless technology.
The technology operates at a data rate of 1 megabit per second and offers a range of five to about 10 meters, compared to Bluetooth's 3 Mbps and 10 meters.
Unlike Bluetooth—which sends packets at fixed intervals, regardless of how little data they contain, resulting in longer transmission times—Wibree transmits each packet as soon as the previous data is sent.
Because Wibree thus transmits more efficiently, it uses less energy—one-tenth that of Bluetooth. However, Tulimaa noted, as Wibree's data rate increases, its power-consumption advantages decrease.
According to Tulimaa, Wibree circuitry is also less complex and takes up less space, and thus is less expensive, than Bluetooth circuitry.
Nokia envisions Wibree being used with or in place of Bluetooth, which is optimized for applications that transfer large amounts of data and is typically used to link cellular phones, PDAs, computers, and some peripherals.
For example, Wibree on a standalone chip would be good for a small monitor or other device that can't handle Bluetooth's power consumption or the amount of space its circuitry occupies, said Jerson Yau, a research analyst with IDC Australia.
Wibree could also be used on a Bluetooth chip in dual-mode devices, which could include cellular phones, laptops, or PCs. These could connect to Wibree, Bluetooth, and other dual-mode devices, bringing increased capabilities to all the participating machines.
Wibree's best market may be medical monitoring equipment, for transmitting patient data to a doctor's or nurse's PC or laptop, according to Tulimaa. To be most useful and convenient, such equipment must be small and wireless and be able to run for hours without needing new or recharged batteries, he explained.
Nokia is working with other companies on a Wibree interoperability standard, which it expects to release during the first half of next year.
Robin Duke-Woolley, managing director of Harbor Research Europe, expressed skepticism about the need for Wibree, given the availability of other inexpensive, low-power wireless technologies such as ZigBee. However, he said, Wibree might replace Bluetooth in a few cases.
News Briefs written by
Linda Dailey Paulson, a freelance technology writer based in Ventura, California. Contact her at ldpaulson@yahoo.com.
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