Researchers from the Department of Languages and Systems and Software Engineering at the Universidad Politécnica de Madrid’s School of Computing have developed a prototype metropolitan quantum key distribution network that will be ready for deployment by Telefónica on any Spanish urban telecommunications network by 2010. The group researching this quantum cryptography network are members of the Quantum Computing and Information Research Group based at the School of Computing, led by Vicente Martín and of the Department of Network and Services Security at Telefónica I + D.
The prototype is being developed as part of the CENIT-SEGUR@ - Security and Confidence in the Information Society research and development project. The project partners form a consortium of twelve companies and fifteen public research institutions, including the UPM’s School of Computing, led by Telefónica I + D. The project has a budget of 31 million euros.
The aim of this project is to light the way towards a new generation of integral security solutions, capable of dealing with the telecommunications security risks now threatening conventional networks.
The security of conventional public key cryptography methods is founded on the confidence that an attacker does not have computing power or mathematical knowledge enough to decrypt the. But these methods are becoming less secure as computing power increases and mathematical methods grow in sophistication.
Quantum key distribution depends on quantum mechanics and provides completely different ways of generating cryptographic keys, that are the building blocks of many security schemes, reaching unprecedented security levels.
Using a complex protocol, a sender and a receiver exchange a series of qubits encoded in photons. This way, they can agree on a highly secure and virtually unbreakable key, because, according to the principles of quantum physics, any attempt at intercepting a qubit would be detected by the receiver, making for confidential information exchange.
A qubit (from quantum bit) is the minimum and therefore basic unit of quantum information. Quantum key distribution technology uses individual photons or qubits over optical fibre, free space or even satellite links.
On any network
The metropolitan quantum key distribution network developed by the CENIT SEGUR@'s team of researchers, composed of physicists, computer scientists, telecommunications engineers and mathematicians, can coexist with traditional communication networks. In actual fact, this is its main advantage. The network already has all its key components and has successfully passed its first experimental tests.
At present there are only three networks like this in the world, and the metropolitan quantum network developed at the UPM’s School of Computing is the only network offering direct links to end users by including technology also for the access segment. Also it will be made compliant with the standards on networked quantum devices, that are being developed at the European Telecommunication Standards Institute andin the definition of which the UPM’s School of Computing team is also participating.
This social application of the quantum key distribution network has been achieved by developing a number of protocols enabling its deployment on conventional telecommunications networks, without the use of these networks affecting qubit circulation.
Although this technology was first proposed in the 1980s, there is now a second generation of quantum key distribution devices, with several prototypes on the market.
The main aim of the metropolitan quantum key distribution network developed at the UPM’s School of Computing is to overcome the current limitation of point-to-point links and non-shared fibersand make it available to small and medium-sized enterprises and even multiple end users through the shared use of the communications infrastructure.
The prototype intends to structure a quantum key distribution network using a metropolitan ring and serving a number of end users through an access network, that will use quantum links on the conventional network infrastructure.
Although the current telecommunications network is generally based mainly on copper, Telefónica is now deploying a new passive optical fibre network that will allow qubit transmissions. The qubits will coexist with but not interfere with the conventional telecommunications photons.
The fundaments of this research were presented at the quantum networks conference held at Vienna a month ago as part of the European SECOQC project. The presentation focused on the feasibility of quantum key distribution data transmission over a commercial telecommunications network.