Quantum Computing And Cybersecurity

Quantum Computing, Stripe in blue and red

Published: 14 November 2022

Reading time: 3 minutes

In September 2019, Google managed to build a quantum computer. Traditional Computers make use of the binary system, which means they are built up of digital bits which can have a value of either 1 or 0.

Currently emerging Quantum Computers however are built up of quantum bits, so-called “qubits”. Due to certain physical properties, these qubits can exist in multiple states at once, meaning a qubit can represent the value 1, 0, or 1 and 0 simultaneously. 
The Sycamore chip works with 53 qubits. This allows Quantum Computers to work on many computations in parallel and hence exponentially speed up the time it takes to process a task. As a consequence Quantum Computers can solve problems that had been far too computationally intensive, even for current super-computers, to calculate.

Whereas this acceleration of computational power has major benefits and could lead to breakthroughs in many areas like science and medicine, it also brings significant risks.
As mentioned, Quantum Computers have the capability to solve highly complex problems. This however represents a threat when faced with problems that are not supposed to be solved. These are for example mathematical problems used in cryptography.

Cryptography describes the discipline of transforming clear data into ciphers in order to restrict who can read the information. There are two main types of cryptography: symmetric and asymmetric cryptography. In symmetric schemes, the same key is used to encrypt and decrypt the data, while in asymmetric schemes (also called public key) a pair of keys, a publicly shared key for encryption and a private key for decryption, is generated.

Both of these types of cryptography find applications for example when browsing the internet. As symmetric encryption is essentially much faster than public-key encryption, it is used to encrypt communication and information. Public-key cryptography is used to securely exchange symmetric keys and to create and authenticate digital signatures. For example, when visiting a website that uses HTTPS protocols, the browser will authenticate the certificate of the website using public-key encryption and thereafter set up a symmetric key that encrypts the communication from and to the website.

As a result, the authenticity of the website has been checked and all information shared cannot be viewed by a third entity.
The problem is that most cryptographic schemes are based on mathematical problems and their security lies in the fact that these problems cannot be solved. However, as soon as sufficiently powerful Quantum Computers exist, the consequence is that the majority of standard cryptographic schemes today will no longer be secure and object to attack, hence eavesdropping and to digital identity theft.

They may not hit mainstream news often, but major developments in the world of quantum computing are happening all the time. In the first few weeks of 2021 alone, one group of Chinese scientists revealed the world’s first quantum communication network, while another Chinese team launched the county’s first home-grown quantum operating system. The French government, meanwhile, announced a €1.8 billion plan to invest in quantum computers and related technologies, and IBM updated its roadmap for its quantum computing development confirming that it aims to have an 1121 qubit processor in operation by 2023.

Which cryptographic algorithms are vulnerable to quantum computers?
All the asymmetric algorithms in use today are vulnerable because they solve mathematical problems by integer factorization or by calculating discrete logarithms.
A conventional computer finds these problems difficult, but Shor's algorithm can solve them very easily.

That means a hacker with a quantum computer could gain access to confidential data, steal someone else's identity or falsify transactions or legal contracts.
The new algorithms will be quantum-resistant because they will be based on mathematical problems that are among the most difficult to solve, even for a quantum computer.

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