Quantum cryptography: Digital security will get a shot in the arm

That’s where quantum cryptography comes in. It’s a fascinating blend of physics and computer science that promises to revolutionize how we secure our communications.

Quantum computers, which can process vast amounts of information simultaneously, could break existing encryptions in seconds. This threat has spurred interest in quantum cryptography, which is safe from decryption (in theory). 

Given the value of secure communication for defence, finance and other purposes, countries worldwide invest heavily in quantum cryptography.

At its core, it is a method of securing transmissions using the principles of quantum mechanics, a branch of physics that deals with the behaviour of particles on the tiniest scales, like atoms and photons, and separately, through the use of unimaginably complex numbers. Quantum Key Distribution (QKD) and Post Quantum Cryptography (PQC) are the main competing methods.

Also read: ‘India’s Quantum Mission geopolitically key, to be actualized soon’

PQC is about pure mathematics, in which next-level cryptographic algorithms are made to run on traditional computers and are so complex that they can’t be broken even by a quantum computer. In contrast, QKD allows two parties to share a secret key that can be used to encrypt and decrypt messages. 

Its magic lies in how the key is shared. Using quantum particles, typically photons (particles of light), the key is transmitted in such a way that any attempt to eavesdrop on a missive would disturb the particles and alert the parties intrusion. 

This method uses the Heisenberg Uncertainty Principle, which states that certain properties of a quantum particle cannot be measured without altering them (bit.ly/3Aty2Yw).

In simpler terms, QKD works like this: First, a stream of photons (light particles) are sent that represent bits of information in a form recognizable by computer chips (0s and 1s), but in different ‘quantum’ states. These states could be the direction in which the photons vibrate (vertical, horizontal, or diagonal). 

The receiver’s device can measure the state of these photons. The uncertainty principle means if someone tries to intercept and measure them, their ‘quantum’ state is disturbed. The receiver and sender can then compare a portion of their received and sent photons to check for discrepancies. 

Inconsistencies would mean the line has been compromised. If it is clear nobody has eavesdropped, they can use the detected photons to generate a shared secret key. 

This key is used to encrypt messages, thus ensuring greater security than assured by methods such as the Rivest-Shamir-Adleman algorithm, which relies on factoring large numbers (bit.ly/3WMK7PS).

The US has been a significant player in the quantum race, with substantial investments through government initiatives and private collaborations. The US National Quantum Initiative Act of 2018 aims to accelerate quantum research. 

Also read: Nvidia Joins Ongoing Race in Quantum-Computing Cloud Services

Organizations like the National Institute of Standards and Technology (NIST) are developing quantum-resistant algorithms, even as firms like IBM, Google and Microsoft explore the field.

China pursues quantum supremacy with significant state backing. In 2016, it launched the world’s first quantum communication satellite, Micius, which achieved long-distance QKD by transmitting quantum keys between ground stations separated by over 1,200km (bit.ly/3yCWl5H). 

Additionally, China has built the world’s most extended land-based quantum communication network, linking Beijing and Shanghai across 2,000km (albeit with over 30 nodes, each of which may be a weak link).

The EU is making significant strides in quantum cryptography, focusing on collaboration and integration across member states. The Quantum Flagship initiative, launched in 2018, is a €1 billion, 10-year programme to advance quantum technologies, including quantum cryptography. Being a union of sovereign states, the EU is also working on standardizing protocols, which is crucial for widespread adoption.

India launched the National Quantum Mission last year. It aims to spend about $1 billion through 2030, including on building 2,000km of secure networks on the ground and quantum-encrypted satellite communication systems.

Several challenges remain. Using QKD currently requires specialized hardware, such as single-photon detectors and quantum repeaters, which must be scalable and cost-effective for widespread use. 

Additionally, transmitting quantum keys over long distances, especially in real-world environments beyond controlled laboratory settings, presents major technical hurdles.

Moreover, the global quantum cryptography race raises concerns about cybersecurity on an international scale. If one country achieves quantum supremacy before others, it could significantly imbalance global security dynamics. 

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However, collaborative efforts among nations and the rapid pace of technological advancement provide hope that quantum cryptography will eventually become a cornerstone of secure global communications.

As quantum technology matures, we can expect it to play a crucial role in safeguarding information in the digital age. The race to harness quantum power is well underway, with the potential to redefine the shaky digital security we endure today.