Quantum key distribution is a secure communication method that makes use of the properties of quantum mechanics to share a secret key between two parties. This key can then be used to encrypt and decrypt messages sent between the parties. Quantum communication is a field of physics that studies the transmission of information using quantum mechanical effects. Quantum entanglement is a phenomenon in which two particles become intimately linked, even if they are separated by large distances. This entanglement can be used to transmit information instantaneously between the particles, regardless of how far apart they are. Quantum cryptography is a method of securely transmitting information using the principles of quantum mechanics.

Two Steps Ahead: Researchers Create Attack-Proof Quantum Communication

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Quantum Key Distribution, a method of secure communication, uses quantum mechanics to encrypt data. Although Quantum Key Distribution’s security is inherently unbreakable, attackers could still steal vital information if it is not properly implemented. Side-channel attacks may be used by attackers to capitalise on weaknesses in the information system to spy on secret key exchanges.

Two methods to make sure that Quantum Key Distribution communications are safe from attack have been developed by researchers at the National University of Singapore (NUS). One is experimental and the other theoretical. The first protocol is a highly-secure cryptography protocol that can easily be used in any network that requires long-term security. The second is a device – the first of its kind – designed to protect Quantum Key Distribution systems from bright light pulse attacks by creating a power threshold.

Nobody can take today’s most complex security software for granted due to rapid advances in algorithmic research, and other areas of quantum computing. These two new approaches promise to ensure that information systems used for banking, healthcare, and data storage are protected from future attacks.

Future-proof quantum communication protocol

In Quantum Key Distribution, there are two measurement settings. One is used to generate the key; the other to verify the channel’s integrity. The NUS team demonstrated that their protocol allows users to independently test another party’s encryption device using two different key generation settings. They showed that it is harder for an eavesdropper to steal information by providing additional key-generating measures for users.

The new protocol is simpler to set up than the original Quantum Key Distribution protocol that was device-independent. It is also more resistant to loss and noise and provides quantum communications users with the best level of security while allowing them to verify their key generation devices.

This setup ensures that all information systems using device-independent Quantum Key Distribution are free from misconfiguration and mis-implementation. It makes data safe from attackers, even though they may have unlimited quantum computing power. This method could create a secure information system that eliminates all side-channel attacks. It should also allow end-users to easily monitor security implementations with confidence.

First of its kind quantum power limiter device

Quantum cryptography uses optical pulses of very low light intensity to exchange data on untrusted networks. Quantum entanglement can be used to secure secret keys, create truly random numbers, or even create banknotes that cannot mathematically be forged.

Experiments have shown that bright light pulses can be injected into the quantum cryptosystem to compromise its security. This side-channel attack strategy uses the fact that brightly injected light is reflected back to the outside world, which reveals the secrets kept within the quantum cryptosystem.

The NUS researchers published a paper in PRX Quantum of 7 July 2021. It describes their first attempt to solve the problem. The device uses thermo-optical defocusing effects that limit the energy of the incoming sunlight. Researchers use the fact that bright light causes a change in the refractive index of transparent plastic material embedded within the device. This allows it to send only a fraction of the light through the quantum channel, creating a power limit.

The power limiter used by the NUS team can be described as an optical equivalent to an electric fuse. However, it is reversible so that it does not blow up when the energy threshold has been exceeded. It is cost-effective and easily made with off-the-shelf components and doesn’t even require power and can easily be added to any quantum cryptography systems to increase its implementation security.

It is imperative to close that gap between theory and practice in quantum secure communications if it is to be used for the future Quantum Internet. This holistic approach is the best as it not only designs more quantum protocols but also engineers quantum devices that closely match the mathematical models used by the protocols.

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