Quantum Cryptography: One Step at a Time

The National Institute of Standards and Technology (NIST) has taken a step towards using conventional high-speed networks such as broadband Internet and LANs to transmit ultra-secure video for applications via quantum key distribution (QKD). QKD uses single photons in different orientations to produce a continuous binary code ("key") for encrypting data. Anyone intercepting the key is detected, thus providing highly secure key exchange. The system produced this "raw" key at a rate of more than 4 million bits per second (4 million bps) over 1 kilometer (km) of optical fiber with an error rate of 3.6 percent. NIST has previously encrypted, transmitted, and decrypted Web-quality streaming video using secret keys generated at 1 million bps in a 1-km fiber QKD system using a different quantum encoding method.

Applications for high-speed QKD might include distribution of sensitive remote video, such as satellite imagery, or commercially valuable material such as intellectual property, or confidential healthcare and financial data. In addition, high-volume secure communications are needed for military operations to service large numbers of users simultaneously and provide multimedia capabilities as well as database access.

Conventional encryption is typically based on mathematical complexity and may be broken given sufficiently powerful computers and enough time. In contrast, QKD produces encryption codes based on the quantum states of individual photons and is considered "verifiably secure." Under the principles of quantum physics, measuring a photon's quantum state destroys that state. QKD systems are specifically designed so that eavesdropping causes detectable changes in the system.

Posted by Jon Erickson at 09:53 AM  Permalink