High speed cryptography

Toshiba makes a quantum breakthrough.

Toshiba Research Europe's Cambridge lab has been talking up a breakthrough in encryption.

Toshiba researchers have demonstrated the continuous operation of quantum key distribution (QKD) with a secure bit rate exceeding 1Mbps over 50km of fibre.

They managed to do this over a 24 hour period at a rate between 100 and 1,000 times faster than any other traffic sent over the same distance.

This was achieved through the use of a light detector for high bit rates and a feedback system that ensures that this bit rate is as high as possible at all times.

The results of the experiments will be published in the science journal Applied Physics Letters and shown off in Tokyo, but in the meantime, Toshiba is suggesting that the technology could be used to power regular occurrences of "one-time pad" encryption, which previously had been complex and restrictive to construct because it requires extremely long keys.

However, it expects that soon it will be able to make these messages a daily occurrence, and not just the privilege of the military.

Dr Andrew Shields, a research director at Toshiba Research Europe, said, "Although the feasibility of QKD with megabits per second has been shown in the lab, these experiments lasted only minutes or even seconds at a time and required manual adjustments."

Researchers they may be, but they have not done a huge amount of digging into how unique this actually is.

"To the best of our knowledge this is the first time that continuous operation has been demonstrated at high bit rates," added Shields.

"Although much development work remains this advance could allow unconditionally secure communication with significant bandwidths."