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

livemint.com:

Imagine sending a secret message to someone. Traditionally, you might use a unique code or encryption to keep it safe from prying eyes. But can you guarantee that no one intercepts or tampers with your message, especially without being detected? 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.

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.