[+/-] Quantum cryptography network debuts

BBN Technologies, Harvard University and Boston University researchers have built a six-node quantum cryptography network that operates continuously to provide a way to exchange secure keys between BBN and Harvard.

Quantum cryptography schemes allow a pair of correspondents to securely exchange a key that will unlock a scrambled message. The schemes call for transferring each bit of information using a single photon. The systems are potentially very secure because the quantum state of a particle cannot be observed without altering it. If the random string of bits that make up the key have been observed, it will be obvious to the sender and receiver and the key can be discarded.

Quantum cryptography has the potential to guarantee perfectly secure communications, but until now all of the prototype systems have been point-to-point links rather than networks that share connections. "Any node in the network can act as a relay," said Chip Elliott, a principal scientist at BBN Technologies. The researchers will soon move one of the network nodes across town to link Boston University into the network, said Elliott.