Toshiba Europe has reached the demonstration phase of what it claims is the first system to use quantum cryptography to secure a real-time video and voice data stream.

Developed by a 30-person team of scientists working at the company’s Cambridge Research Laboratory , the company says that its immediate plans are to develop the technology for use in specialised video-conferencing systems, where high levels of security are essential.

Longer term, it could also be used to secure the transmission of any other high-bandwidth communication, as well as the movement of large numbers of sensitive files.

The new system works by using the basic principles of quantum-based cryptography – that data encrypted using particles of light to correspond to each bit of data cannot be tampered with without detection – to build a system where every video frame is encrypted with its own key and can therefore be verified. Apart from the massive computational element of hacking such a data stream, the attacker’s presence cannot be hidden. The keys can also be regularly and securely refreshed, adding to security.

The current system runs at a throughput of 100 frames, or keys, per second, making it practical for everyday video links, with an effective data and key rate of 25 kilobits per second between two quantum encryption servers via a fibre optic link. Usable links have been demonstrated at distances of 122 kilometres.

Project head, Dr Andrew Shields, was confident the system would be on the market within “two to three years,” now that all the fundamental engineering problems had been solved. It had been shown to an audience of officials from the UK government this week, and had garnered a positive reaction, he confirmed.

Apart from the security innovation, the system was much easier to manage than a conventional public key infrastructure (PKI) system because it did not require a database infrastructure to store keys. He characterized it as being more expensive in terms of startup costs, but lower cost in ongoing management.

“The cost of a system like this will be comparable to that of a high-end firewall,” Shields said.

He admitted the system had one theoretical weakness – the links between the quantum encryption servers on the edge of a network and the PCs displaying the video would not use quantum encryption. The design of the system assumed that the insecure part of the link would always be outside of the network rather than inside the organisation. However, he pointed out that it should be possible to build a system of distributed servers within the network itself to minimise this risk.

It’s hard to assess the marketability of quantum cryptography because there is no market currently to speak of. However, almost every communications company is known to be working on applications of the technology, so one can assume it will find an important niche in years to come.

The major barrier will be whether people are willing to pay any premium for a quantum-based system over conventional public key designs. In the case of static data applications that is highly questionable – conventional encryption is more than secure enough for the foreseeable future.

However, video could turn out to be one application where the ultimate security of quantum physics helps ignite a new, if specialised, market.