Ensuring Secure Transmissions via Quantum Key Distribution


One of the key challenges faced by multinational corporations and governments is ensuring the secure transmission of data across the internet. Despite the use of data encryption protocols, there are still security risks associated with sending sensitive data between parties. Malevolent operators may be able to crack mathematical security protocols or acts of sabotage or carelessness may expose cryptographic keys inadvertently, allowing other parties to eavesdrop or intercept a message without being detected.

That’s where the use of quantum cryptography may yield benefits. Quantum cryptography uses the principles of quantum mechanics to send secure messages. Unlike mathematical encryption schemes, quantum communications-based cryptography is truly unable to be hacked.

Quantum cryptography, or quantum key distribution (QKD), uses a series of photons (light particles) to transmit data from one location to another over a fiber optic cable. By comparing measurements of the properties of a fraction of these photons, the two endpoints can determine what the key is and if it is safe to use. The security lies in the fact that a quantum particle can’t be measured without changing or disturbing it. While some quantum properties of a particle can be cloned, it’s impossible to clone the entire particle.

How the Quantum Cryptographic Process Works

To initiate a quantum-secure message, a sender transmits photons through a filter that will randomly assign one of four possible polarizations and bit designations to each photon. These include vertical (one bit), horizontal (zero bit), 45 degree right (one bit), or 45 degree left (zero bit). The photons travel to a receiver, which uses two beam splitters (horizontal/vertical and diagonal) to “read” the polarization of each photon. The receiver does not know which beam splitter to use for each photon and has to guess which one to use.

After the stream of photons have been sent, the receiver tells the sender which beam splitter was used for each of the photons in the sequence they were sent. The sender compares that information with the sequence of polarizers used to send the key. The photons that were read using the wrong beam splitter are discarded, and the resulting sequence of bits becomes the key.

Challenges remain with deploying quantum cryptography, largely due to the same principles of quantum mechanics that provide the enhanced security. When these quantum bits (qubits) are in a state of entanglement (holding multiple states at once), quantum physics ensures that the message is not read, copied, or altered in any way. If any of these activities occur, the state of the photon will change and will be detected by the endpoints.

However, while it’s possible to send qubits to short distances over telecommunications fibers up to roughly 60-100 miles, further distance is limited by decoherence, a situation where the qubits being measured lose their specific quantum properties. As a result, a key future goal for researchers and telecommunications concerns is building a quantum-secure internet that can support sending quantum keys across greater distances. Several companies are working on an approach to the problem:

  • ID Quantique (IDQ): IDQ’s business is in providing quantum-safe network encryption solutions for the protection of data in transit over computer networks. The company has government, enterprise, and academic customers in more than 60 countries.
  • Qubitekk: Working closely with two of the four major utilities in California, Qubitekk is developing and trial testing a quantum cryptography solution that will provide quantum-safe authentication and encryption to automation devices in the field.
  • QuintessenceLabs: QuintessenceLabs is active in the QKD development space with deployments using standard networking components. The company believes that in the future, a worldwide QKD network using satellites will be able to safely exchange keys and transport them around the globe.
  • Battelle: Battelle is working with IDQ to create a new quantum device called a QKD Trusted Node. The QKD Trusted Node will allow a quantum network to expand the distance of QKD and allow multiple destinations while retaining the secure nature of QKD.

Several Years Away

Tractica believes that the development of quantum networks may be several years away, given that current quantum computing technology has yet to be perfected. Even the most advanced quantum computers have yet to establish quantum advantage, or the ability to perform specific tasks more efficiently than classical computers. Tractica discusses the current state of the quantum computing market in its Quantum Computing for Enterprise Market report, which includes market analysis and forecasts for quantum-related hardware, software, storage, and services across 15 industry sectors.

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