Quantum Cryptography

While still in the early stages of development, quantum cryptography or quantum encryption possesses the potential to be infinitely more secure than any existing method of encryption. By definition, it refers to various cybersecurity methods for encrypting and transmitting data in a secure manner, derived from the laws of quantum mechanics. It could, if harnessed properly, beat all previous cryptographic algorithms and could even be theoretically unhackable.

Discovered in the 1980s, the rapidly-evolving technology was first classified as a threat to our traditional security systems in 1994, barely 15 years after its invention. It takes the properties of quantum physics and applies it to solve complex problems orders of magnitude faster than our fastest cutting-edge classical computers. As ‘quantum’ suggests, the process utilizes the principle of parallel computing, enabling multiple variables and their results to be evaluated in a fascinatingly small span of time. Interestingly, when it comes to sequential tasks such as addition, classical computers are faster by orders of magnitude. Their building blocks, qubits, are the quantum mechanical analog of a classical bit, and exist in a constant state of superposition of 0 and 1 (using the Hadamard Gate). The Pauli-X Gate flips the state of a qubit from 0 to 1 and vice versa. A system of n interacting qubits can efficiently do the work of 2^n bits.

As technology advanced, cryptosystems diverged into two main categories: symmetric and asymmetric systems. Symmetric systems utilize 1 secret key to encrypt as well as decrypt data, while asymmetric systems use 1 public key that the general populace has access to and private keys that authorized individuals alone can access. Both types create their respective keys by multiplying large prime numbers.

As per Shor’s Factoring Algorithm, factoring a large number on a classical computer would require an immense amount of computing power, even with which it would take many lifetimes. Compared to that, a quantum computer at full functionality would potentially be able to decrypt modern encryption algorithms such as RSA or AES in a matter of minutes.

For securing during transmission, quantum machines use techniques such as:

• Quantum Key Distribution (QKD) for keys and
• Quantum Coin-flipping for data.

These incorporate the No-cloning Theorem (the impossibility of creating identical copies of an unknown state), and immeasurability without disturbance (measuring a quantum system resulting in a measurable alteration of the components).

Apart from constructing a fully functional quantum computer, scientists from the National Institute of Standards and Technology (NIST) have stated that the goal Post-Quantum Cryptography (PQC) is to “develop cryptographic systems that are secure against both quantum and classical computers, and can interoperate with existing communications protocols and networks”. Becoming quantum-proof is an aspect that has multiple loopholes as quantum machines with relatively higher processing power can break down lower machines’ defenses easily.

From safeguarding state secrets to corporate shielding, the use cases for this technology abound, but so do the risks. As scientists worldwide strive to make quantum cryptography a practical reality, the fact that it will make all the cryptographic algorithms available today obsolete must be acknowledged. The usage of quantum cryptography to shield against invasion of privacy by external quantum computers may be our only solution for securing private information and credentials.

Although quantum computing was once thought of to be theoretical and far-fetched, recent advancements have proven that in a few decades, the advent of the quantum age will be upon us.

Sources:

1. https://www.ibm.com/topics/quantum-cryptography
2. https://www.classiq.io/insights/shors-algorithm-explained
3. https://www.techtarget.com/searchsecurity/definition/quantum-key-distribution-QKD
4. https://kaustubhrakhade.medium.com/shors-factoring-algorithm-94a0796a13b1
5. https://www.cdvi.co.uk/learn-about-access-control/what-is-access-control/what-is-aes-encryption-and-how-does-it-work/
6. https://en.wikipedia.org/wiki/Quantum_coin_flipping
7. https://softwaredominos.com/home/science-technology-and-other-fascinating-topics/quantum-computing-beyond-qubits-part-4-shors-algorithm-for-factoring-large-numbers/#:~:text=The%20problem%20that%20Shor%27s%20algorithm,many%20cryptographic%20systems%2C%20including%20RSA
8. https://softwaredominos.com/home/software-engineering-and-computer-science/understanding-rsa-the-mathematics-behind-secure-encryption/

Author: Rakshita Vijay