QUANTUM KEY DISTRIBUTION (QKD)

1. QUANTUM KEY DISTRIBUTION (QKD) OVERVIEW Quantum Key Distribution, often called quantum cryptography, uses physics rather than math to encrypt transmitted data. Rather than an algorithm creating a sequence of 1's and 0's, photons are polarized to random quantum states and used as the cryptographic key. As a result of quantum mechanics, these photons cannot be intercepted and observed between sender and receiver without changing the quantum state and thereby alerting the receiver to tampering. For this reason, quantum key distribution is considered the best data encryption available. WHY NOT? Some problems facing QKD include cost, need, and research into QKD’s vulnerabilities. First, the receiver equipment alone costs $20,000-80,000 and only works within short distances from the transmitter. Second, conventional cryptography is adequate. There is not currently a need for more advanced technology. Third, as exciting as quantum cryptography is, it is equally exciting for some to develop ways to break quantum encryption even before it is commonplace. THEN AND NOW 1989, first quantum cryptography system, built by Charles Bennett, Gilles Brassard, and John Smolin, sent a key over a distance of 36 centimeters. 1999, Los Alamos National Laboratory successfully sent a quantum key through a 31 mile long optical fiber and developed a system to send a quantum key through the air up to 10 miles. 2004, DARPA set up a 10 node network in Massachusetts running QKD. 2008, a computer network protected by QKD connected six locations in Vienna with another node more than 40 miles distant for a scientific conference. 2011, network designed to test the reliability of QKD in continuous long-term operation was shut down after a second successful attempt to break the security.