Post-quantum cryptography: securing data in the age of quantum computers

Subject :Science and tech

Section: Awareness in IT and computers

Context:

Governments and organisations across the world are rushing to develop quantum computing platforms and advanced security algorithms to defend against such machines. One such example is the U.S. National Institute of Standards and Technology’s Post-Quantum Cryptography Standardisation project.
India has launched the National Quantum Mission.

Security algorithm:

Much of our current security is based on techniques such as RSA, elliptic curves, Diffie-Hellman key exchange and almost all of them rely on a few “hard” mathematical problems, such as factorisation and the discrete logarithm problem.
In 1994, Peter Shor developed a quantum algorithm that can break all of these with ease.
While Shor’s technique poses a threat to certain security algorithms, there are alternative methods that remain unaffected.
Lov Grover’s quantum algorithm can often be fixed by increasing the key or password lengths.
Some common “symmetric” security algorithms such as AES are not badly affected. (Symmetric key algorithms use the same password to lock and unlock the information.)

Post-quantum cryptography:

Post-quantum cryptography involves exploring alternative techniques to counter vulnerabilities against quantum attacks.
In cryptography, post-quantum cryptography (PQC) refers to cryptographic algorithms (usually public-key algorithms) that are thought to be secure against a cryptanalytic attack by a quantum computer.
- The problem with currently popular algorithms is that their security relies on one of three hard mathematical problems: the integer factorization problem, the discrete logarithm problem or the elliptic-curve discrete logarithm problem.
- All of these problems could be easily solved on a sufficiently powerful quantum computer running Shor’s algorithm.
While Shor’s algorithm poses particular concerns for certain methods, the field has rapidly evolved with promising approaches such as lattice algebra, multivariate cryptography, isogeny-based techniques, and code-based cryptography.
One promising technique, supersingular isogeny Diffie-Hellman key exchange, was considered secure by many until it was utterly broken by Wouter Castryck and Thomas Decru last year.

Bits of physics:

We have developed circuits that can do logical computations incredibly fast and with astounding reliability.
New kinds of gates can be built using the laser, maybe a prism “naturally” computes a square root or something.
The principles of quantum mechanics enabled a set of gates that were utterly impossible to build using electronics.
In other words, using quantum states to represent logic allows us to compute very differently.
This new, different kind of computation is very powerful. Many things that were complex and cumbersome when run on electronic logic become incredibly simple on a quantum system.

Challenges:

This comes with its own problems.
- Current attempts are incredibly error-prone and have many missing pieces.
However, many experts believe that this is inevitable and we will eventually develop such machines.

Quantum computer:

A quantum computer is a computer that exploits quantum mechanical phenomena.
At small scales, physical matter exhibits properties of both particles and waves, and quantum computing leverages this behaviour using specialised hardware.
Classical physics cannot explain the operation of these quantum devices, and a scalable quantum computer could perform some calculations exponentially faster than any modern “classical” computer.
In particular, a large-scale quantum computer could break widely used encryption schemes and aid physicists in performing physical simulations; however, the current state of the art is largely experimental and impractical, with several obstacles to useful applications.

National Quantum Mission (NQM):

It’ll be implemented by the Department of Science & Technology (DST) under the Ministry of Science & Technology.
The mission planned for 2023-2031 aims to seed, nurture, and scale up scientific and industrial R&D and create a vibrant & innovative ecosystem in Quantum Technology (QT).
With the launch of this mission, India will be the seventh country to have a dedicated quantum mission after the US, Austria, Finland, France, Canada and China.