Raw code for ´unbreakable´ quantum encryption has been generated at record speed over optical fiber at NIST. The work is a step toward using conventional high-speed networks such as broadband Internet and local-area networks to transmit ultra-secure video for applications such as surveillance.
The NIST quantum key distribution (QKD) system uses single photons, the smallest particles of light, in different orientations to produce a continuous binary code, or “key,” for encrypting information. The rules of quantum mechanics ensure that anyone intercepting the key is detected, thus providing highly secure key exchange.
The laboratory system produced this “raw” key at a rate of more than 4 million bits per second over 1km of optical fiber, twice the speed of NIST´s previous record, reported just last month. The system also worked successfully, although more slowly, over 4 km of fiber.
After raw key is generated and processed, the secret key is used to encrypt and decrypt video signals transmitted over the Internet between two computers in the same laboratory. The high speed of the system enables use of the most secure cipher known for ensuring the privacy of a communications channel, in which one secret key bit, known only to the communicating parties, is used only once to encrypt one video bit. Compressed video has been encrypted, transmitted and decrypted at a rate of 30 frames per second, sufficient for smooth streaming images, in Web-quality resolution, 320 by 240 pixels per frame.
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.