Quantum key distribution encryption demonstrated at Los Alamos

Ars Technica : Key distribution is a common system for encrypting messages, whereby two people who wish to communicate share a key that is used for both coding and decoding their transmissions. However, the system is often vulnerable to interception or decryption if the key is not sufficiently complex. Quantum key distribution increases the security by exploiting entanglement to create a tamper-proof key. A team at Los Alamos National Laboratory has now revealed the first known working quantum key distribution system. They built a small end-user piece of hardware that combines a single-photon source and a true random number generator. The random number generator sets the value of a bit encoded on each photon, which is then sent out over a fiber-optic cable. The system uses a single server with photon receivers to measure the bits, and it publicly states which ones it measured. If none of them appear to have been tampered with, the server uses the bits to build a secure key. The key can then be used to safely transmit data. The Los Alamos system currently allows for communication only with the server, but it could be adjusted to allow for communication among different users.