Posted on: 17 april 2024

Quantum Key Distribution (QKD): The Key to Untappable Communication

We live in an era where our life is intertwined with technology. As we rely more and more on digital ecosystems in almost every aspect of our life, from online transactions, bank details, Personally Identifiable Information (PII) to national security or defense communications, the threat from cyberattacks becomes more prominent. With the tremendous advancements in technology, we have realized that current cryptographic systems are not enough to keep our data secure.

Although we don’t have powerful quantum computers today, our data is still vulnerable to store and decrypt later attacks which makes the situation more real. This is the reality we face today, and we must take actions to move from classical cryptography towards a safer and more secure cryptographic system, Quantum Key Distribution (QKD). Come join us in this journey in understanding more about QKD and how it can help us to secure our data.

What is QKD?

At its core, QKD is a cryptographic key distribution protocol designed to generate keys to establish secure communication channels between two parties, typically referred to as Alice and Bob. Unlike conventional cryptography methods that rely on complex mathematical algorithms, QKD leverages the unique properties of quantum particles, such as photons, to create unbreakable encryption keys.

As QKD uses quantum principles to generate random secret keys, the information is stored in the qubits before processing into secure key material. These qubits are very sensitive and can be easily disturbed by an external entity. Also, unlike classical bits which can be copied and stored, qubits cannot be copied due to the “no-cloning” theorem. Due to these quantum properties, the communicating parties can detect anomalies in the system if any or the presence of an eavesdropper during communication.

How does QKD work?

To understand how QKD works, let’s consider a general setting or a real-world scenario where two parties say Alice and Bob would like to communicate with each other using a secure key. But there will also be an interceptor in the middle trying to steal the key or planning a man-in-the-middle attack, let’s call this interceptor Eve. Quantum Key Distribution works on BB84 protocol at its core to generate and distribute secure keys using quantum mechanics.

The protocol starts by encoding a message in quantum bits or qubits. There are various qubit encoding techniques but one of the most common in QKD is basis encoding, for example the data can be encoded in terms of X basis or Z basis. Say Alice encodes some data in a combination of randomly selected basis for each qubit. Alice then transmits this data to Bob through a quantum channel, i.e. in the form of photons. An amazing thing to notice here is that even though the quantum data transmission happens in the presence of an eavesdropper, any attempt to intercept this data leads to disturbing the quantum state of the qubits exposing the presence of Eve to Alice and Bob.

Upon receiving the qubits, Bob randomly chooses a measurement basis (X or Z basis) for each qubit and performs measurement on the qubits. Alice and Bob then compare their chosen basis through a public channel. As they choose basis randomly, after comparison they only keep the measurements which match, discarding measurements which were different. At the end of this process, Alice and Bob will retain the measurements that match which now forms the raw key material. There are many processes like Sifting, Error Correction, Privacy Amplification further applied to refine the key to make it more secure.

QKD Applications

With this cutting-edge quantum-based cryptographic technology, we can get untappable internet by generating secure keys leading us to various applications. In the realm of national security and defense, secure communication is not just a luxury – it’s an absolute necessity. Government agencies and defense organizations worldwide are turning to QKD to safeguard classified information and communications networks. The financial sector is a prime target for cybercriminals seeking to exploit vulnerabilities and gain access to valuable financial data. Banks, trading firms, and financial institutions are increasingly adopting QKD to fortify their networks and protect against cyber threats.

In healthcare and biotechnology, protecting patient data and research findings is paramount. QKD offers a solution to the privacy and security challenges faced by healthcare providers and research institutions. As the backbone of modern communication networks, telecommunications companies are under constant pressure to defend against cyber threats and ensure the integrity of their infrastructure. QKD presents an opportunity to enhance the security of telecommunications networks, protecting against eavesdropping and data interception.

From government agencies and financial institutions to healthcare providers and telecommunications companies, the practical applications of Quantum Key Distribution are vast and far-reaching. By harnessing the power of quantum mechanics, QKD offers a pathway to secure communication channels that are resilient to even the most advanced cyber threats. QKD is not just a theoretical concept – it’s a game-changer, revolutionizing the way we communicate, collaborate, and innovate in a digital world fraught with risks and uncertainties. So, the next time you send a sensitive message or conduct a financial transaction online, remember the invisible guardian standing watch – Quantum Key Distribution, the key to unlocking a safer, more secure future