Quantum cryptography keys sent record-setting distance

Quantum cryptography is one of those security breakthroughs that may hold the key to future networks.  Researchers today said they have sent particles of light serving as “quantum keys over a record-setting 200-kilometer fiber-optic link. The experiment, using mostly standard components and transmitting at telecommunications frequencies, offers an approach for making practical inter-city terrestrial quantum communications networks as well as long-range wireless systems using communication satellites. Stanford University, National Institute of Standards and Technology (NIST) and the NTT in Japan were involved in the test.  The demonstration, described in Nature Photonics, was conducted in a Stanford lab with optical fiber wrapped around a spool. In addition to setting a distance record for quantum key distribution (QKD), it also is the first gigabit-rate experiment—transmitting at 10 billion light pulses per second—to produce secure keys. The rate of processed key production—the keys corrected for errors and enhanced for privacy—was much lower due to the long distance involved, and the key was not used to encrypt a digital message as it would be in a complete QKD system, the researchers said in a release.  QKD systems transmit a stream of single photons with their electric fields in different orientations to represent 1s and 0s, which are used to make quantum keys to encrypt and decrypt messages. Properly executed, quantum encryption is “unbreakable” because eavesdropping changes the state of the photons.  In a nutshell quantum cryptography uses single photons of light to distribute keys to encrypt and decrypt messages. Because quantum particles are changed by any observation or measurement, even the simplest attempt at snooping on the network interrupts the flow of data and notifies managers. Quantum cryptography is being used by the military, banks and other organizations that seek to better protect the data on their networks. The government’s interest in all things related to Quantum Information Science continued earlier this year with a couple contracts awarded to BBN Technologies  and HRL Laboratories.  First, BBN, was awarded an almost $3.5 million increment of a $14 million Defense Advanced Research Projects Agency (DARPA) contract to continue work on  military applications of quantum information science.   Meanwhile the quantum cryptography news comes on the heals of a report that American computer engineer Laszlo Kish at Texas A&M University in College Station has used the thermal properties of a simple wire to create a secure communications channel, one that even outperforms quantum cryptography keys. As reported in the New Scientist magazine, Kish says his cipher device exploits a property called thermal noise. Thermal noise is generated by the natural agitation of electrons within a conductor, which happens regardless of any voltage passed through it. But it does change depending on the conductor's resistance. Kish and his collaborators at the University of Szeged in Hungary say this can be used to securely pass information, or an encryption key, down any wire, including a telephone line or network cable. In their device, both the sender Alice and the receiver Bob have an identical pair of resistors, one producing high resistance, the other low resistance. The higher the total resistance on the line, the greater the thermal noise. 

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