I think we all agree, that “Information is Power”. Since people arrived at that realization, they have devised methods to ensure their classified knowledge remain a secret. Encryption, one such method of safeguarding information, has existed since the beginning of time. The Assyrians used it to protect their trade secrets and more recently, the Nazis used the Enigma machine to safeguard their military secrets during World War II.
The breaking of Enigma, by none other than the father of modern computing, Alan Turing, kick-started the era of algorithms and computers. Since then, internet security has relied on encryption algorithms to safeguard communication between two or more parties. Unfortunately, all modern public-key based encryption techniques are set to become futile as we enter the age of Quantum Computing. Quantum Computers can use their exceptional computational power, which is several magnitudes higher than any present supercomputer, to decrypt all secured communication – rendering all known avenues of security meaningless.
At present, public or private keys are used to decipher encrypted information sent from one party to the other. Asymmetric ciphers, like RSA and EEC, use the combination of a private key (which is kept secret) and a public key (which is shared), to decrypt a covert message. They either rely on large integer factorization problem, discrete logarithm problem, or elliptic-curve discrete logarithm problem – to secure information. However, endpoint or side-channel attacks have exposed the fragility of these systems, which has led to the ramp up in key sizes to extend their shelf lives.
However, a powerful quantum computer, running Shor’s algorithm, could easily solve any of the three problems mentioned above, rendering public-key protocols ineffective. While they might not be able to crack encryptions solely based on private-key encryption, a major chunk of information transfer happens via public-keys – and will face the risk of being exposed if attacked by a quantum computer. With the present availability of sophisticated quantum devices and software’s, the Cambridge Quantum Computing (CQC) predicts the limited availability of quantum computers in the next five years.
So, in the presence of quantum computers, can quantum encryption provide long-term security solutions? Quantum Cryptography, in principle, allows parties to encrypt messages such that it changes when third-party tries to read it. This works on the principle of quantum mechanics, in which the state of the system changes even when it’s viewed. Quantum Key Distribution (QKD), the method by which quantum encryption works, will provide an opportunity to create a complete end-to-end encryption over fiber networks, ensuring the security of communication at the physical layer.
However, there are certain underlying problems with QKD. In addition to the technical difficulties to produce single photons, the error rates are noisy in such methods – giving rise to unreliability. As Fiber-based QKD travel limited distances, the need for repeaters ensures “weak spots’ in the system. Owing to their practical limitations, post-quantum public-key cryptography might provide better solutions for real-world communications systems from the threat of future quantum computers.
The giants of the tech industry have jumped onto the bandwagon to research Post-Quantum Cryptography. Google’s New Hope software, a post-quantum key-exchange algorithm, is currently enabled on Chrome Canary, its browser designed for developers. By conducting extensive research, Google hopes to safeguard Chrome from future attacks by Quantum Computers.
Encryption has always evolved in the past – along with the lines of devices that break them. With the era of quantum computers looming in the horizon, it’s up to quantum and post-quantum cryptography to lead the way in the next generation of security applications.