cryptography (3)

City-Sized, Secure Quantum Network...

Physicists Create City-Sized Ultrasecure Quantum Network

Quantum physics experiment has demonstrated an important step toward achieving quantum cryptography among many users, an essential requirement for a secure quantum Internet. Credit: ÖAW and Klaus Pichler Getty Images

Topics: Cryptography, Futurism, Internet of Things, Modern Physics, Quantum Computer, Quantum Mechanics

Quantum cryptography promises a future in which computers communicate with one another over ultrasecure links using the razzle-dazzle of quantum physics. But scaling up the breakthroughs in research labs to networks with a large number of nodes has proved difficult. Now an international team of researchers has built a scalable city-wide quantum network to share keys for encrypting messages.

The network can grow in size without incurring an unreasonable escalation in the costs of expensive quantum hardware. Also, this system does not require any node to be trustworthy, thus removing any security-sapping weak links.

“We have tested it both in the laboratory and in deployed fibers across the city of Bristol” in England, says Siddarth Koduru Joshi of the University of Bristol. He and his colleagues demonstrated their ideas using a quantum network with eight nodes in which the most distant nodes were 17 kilometers apart, as measured by the length of the optical fiber connecting them. The team’s findings appeared in Science Advances on September 2.

Physicists Create City-Sized Ultrasecure Quantum Network, Anil Ananthaswamy, Scientific American

 
 
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Quantum Hush...

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Party line: the new protocol allows 10 parties to share information securely. (Courtesy: University of Witwatersrand)

Topics: Cryptography, Quantum Computer, Quantum Mechanics

A “quantum secret sharing” scheme that allows 10 parties to share information securely – the highest number so far – has been developed and demonstrated by researchers in South Africa. The protocol involves each party performing quantum operations on the photon without measuring its state and the team says it could help increase both the rate at which data is shared on secure quantum networks and how many parties can be involved in the sharing.

In the original quantum key distribution (QKD) protocol, two parties, known as Alice and Bob, communicate by exchanging photons polarized in one of two possible bases over an untrusted link, each varying the polarization basis of his or her transmitter or receiver randomly. At the end of the transmission, Alice and Bob reveal to each other which basis they used to measure the photons sent and received, but not the result of the measurements.  Alice and Bob then announce their results for a sample of the photons in which they measured in the same polarization basis, to check that the emitted polarization always agrees with the received one. If it does, they can use the remaining photons that they measured in the same basis to form a secure cryptography key that allows them to communicate securely using conventional telecoms technology. A third party that intercepts the photons inevitably disturbs their state, so some of Alice and Bob’s measurements disagree and they know the line is bugged.

‘Quantum secret sharing’ scheme allows 10 parties to communicate securely, Physics World

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Threshold Cryptography...

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This artist’s conception of threshold cryptography shows a lock that can only be opened by three people working together. When the threshold cryptosystem receives a request to process information with a secret key, it initially splits the key into shares and sends them to the entire group, each share to a different participant. The three people must agree to work together and also perform their own secret operations on the incoming message. From these actions, each person uses their share key — represented by the three colored circles — to process the message, and then sends the result back to the system. Only the combination of all three partial results can open the lock, reducing the likelihood that a single corrupt party could compromise the system.

 

Topics: Cryptography, Computer Science, Electrical Engineering, NIST

A new publication by cryptography experts at the National Institute of Standards and Technology (NIST) proposes the direction the technical agency will take to develop a more secure approach to encryption. This approach, called threshold cryptography, could overcome some of the limitations of conventional methods for protecting sensitive transactions and data.

The document, released today in a final version as NIST Roadmap Toward Criteria for Threshold Schemes for Cryptographic Primitives (NISTIR 8214A), offers an outline for developing a new way to implement the cryptographic tools that developers use to secure their systems. Its authors are inviting the cryptography community to collaborate with them on NIST’s budding Threshold Cryptography project, which in part seeks to ensure that threshold implementations are interoperable.

“We are kicking the threshold cryptography development effort into high gear,” said Apostol Vassilev, a NIST computer scientist. “Over the coming months, the Threshold Cryptography project will be engaging with the public to define criteria for this work. We want to get feedback from the community so we can consider a variety of threshold schemes and standardization paths.”

Threshold cryptography takes its name from the idea that individual keyholders cannot open a lock on their own, as is common in conventional cryptography. Instead, out of a group of keyholders, there must be a minimum number of them — a “threshold” number — working together to open the lock. In practice, this lock is an electronic cryptosystem that protects confidential information, such as a bank account number or an authorization to transfer money from that account.

NIST Kick-Starts ‘Threshold Cryptography’ Development Effort

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