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Closing the Last Loophole For ­nhackable Quantum Security

A representation of quantum cryptography.

Device-independent quantum cryptography, when perfected, will enable devices to guarantee the confidentiality of messages sent on them.

Credit: Jamie Mills

The perfection of device-independent quantum cryptography will enable devices that guarantee the messages sent on them remain confidential.

The method was inspired by University of Oxford physicist Artur Ekert's conceptualization of a new form of quantum cryptography that uses a stream of photons and involves the sender creating a string of random numbers by measuring a property of each photon. However, the recipient has a separate stream of photons from the same source that are entangled with the sender's; this permits sender and recipient to perform measurements on their respective photons that will help them generate each number of a shared key.

Institute of Photonic Sciences researcher Antonio Acin and colleagues saw Ekert's protocol as a way to prove whether the maker of the device is to be trusted, by applying a Bell test. Experiments by Delft University of Technology researchers demonstrated a Bell test in which the locality and the detection loopholes were concurrently closed, establishing quantum theory as a method for creating a certifiably safe cryptographic system.

There are other factors that could compromise security, such as the physical theft of the cryptographic key--but device-independent quantum cryptography does appear to be achievable. "In terms of being able to verify physical security, it's the best," says the Institute for Quantum Computing's Michele Mosca.

From New Scientist
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