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Details of Grant 

EPSRC Reference: EP/D505941/1
Title: Quantum-cryptographic authentication via digital signatures and quantum public keys
Principal Investigator: Kent, Professor A
Other Investigators:
Ioannou, Dr LM
Researcher Co-Investigators:
Project Partners:
Perimeter Inst for Theorectical Phycs University of Waterloo (Canada)
Department: Applied Maths and Theoretical Physics
Organisation: University of Cambridge
Scheme: Standard Research (Pre-FEC)
Starts: 01 October 2005 Ends: 30 September 2008 Value (£): 175,643
EPSRC Research Topic Classifications:
New & Emerging Comp. Paradigms Quantum Optics & Information
EPSRC Industrial Sector Classifications:
Communications
Related Grants:
Panel History:  
Summary on Grant Application Form
Our everyday-experience is described by the classical laws of physics. The behaviour of all computers and communication devices (mobile phones, pagers, etc.) widely used today can also be described by these classical laws.For about a century, it has been known that the classical laws of physics do not apply to very tiny particles like electrons or photons (particles of light): electrons and photons behave in bizarre ways. This bizarre behaviour is described by the laws of quantum mechanics.Sometimes people need to communicate secrets over a mobile phone or internet connection, like bank PINs and credit card numbers. Cryptography is the field of study that is concerned with how to send messages (e.g. credit card numbers) securely over communication lines. All the cryptographic protocols used on the Internet today to keep secret information secure are based on the classical laws of physics.Quantum information processing is a relatively new research area in which the laws of quantum mechanics are used to design systems (computers, mobile phones, etc.) that can communicate more securely or compute more efficiently than systems in widespread use today.Quantum computers have the ability to crack widely-used, modern, cryptographic protocols easily. Fortunately, quantum mechanics also provides the potential for unbreakable protocols. Quantum key distribution (QKD) is one such protocol, which allows two authenticated parties to communicate perfectly securely. However, this leaves the problem of authentication: how can one be sure that one is communicating with the correct entity?If two people share a secret before they communicate over the Internet, then they can easily identify each other by exchanging some information about their secret. For example, Alice might know that Bob's first pet was called Roy Roger the Super Dog and that no one else knows this. Suppose Alice goes onto the Internet and tries to contact Bob. She can be reassured that she is actually talking to Bob if the person she contacts correctly answers the question What was the name of your first pet? With a more sophisticated protocol, a secret between Alice and Bob can be used so that Alice is absolutely certain that she is talking to Bob.But Alice does not share a secret with everyone she would like to talk to, for example, people she has never met before.In general, it is very difficult for every possible pair of people to share a secret before they communicate. Luckily, though, public-key quantum cryptography allows a framework in which two people can be reasonably sure of each other's identity with just a few extra assumptions involving a trusted third party. This framework uses digital signatures. Such frameworks are computationally secure, meaning that, given enough time, a computer could perform calculations that would break the system.Ideally, we would like to have authentication protocols that are unconditionally secure (perfectly secure), just as QKD is unconditionally secure. We propose to study quantum authentication schemes with a focus on quantum digital signatures, and, as a basis for this, to investigate the feasibility and utility of quantum public keys. Combined with QKD, this would potentially enable an efficient infrastructure for perfectly secure communication on a future quantum Internet.
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Organisation Website: http://www.cam.ac.uk