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#Cybersecurity

Securing systems with post-quantum cryptography

Global Trends
7 Mins.

The journey toward quantum computing and quantum-resistant algorithms is one of the most important technological tasks of our time. Quantum computing will change the very foundation of our business models, technological products, and solutions. As we move toward greater connectedness, every element within our networks must be secured for the future against cyberattacks based on quantum effects

Quantum computing could have the ability to optimize traffic flows, model molecules to develop next-gen lithium  batteries1, or improve health diagnoses by enhancing MRI scanning.2 Quantum computers will be able to do much more than just that, and will revolutionize the way we solve many complex problems. The impressive capabilities of quantum computers are largely enabled by qubits. Unlike traditional computer bits, which only take the value of zeros and ones, qubits exist in more than one state at a time until observed, much like Schrödinger’s cat. This property of being in two states at the same time is known as a superposition. By leveraging superpositions and entanglement, quantum computers can execute multiple computation paths simultaneously. To better understand the importance and necessity of quantum computing, we can look at the “traveling salesperson dilemma.”

Imagine a traveling salesperson needs to visit multiple cities once each and return to the starting point, following the shortest route possible. If this included just three or four cities, one could easily calculate this in one’s head. However, by the time 11 cities must be factored into the equation, there are 20 million possible routes between them. Add just one more city to make it 12 stops and there are now an incredible 240 million possibilities.3 While a traditional computer would effectively use trial and error to find the optimal route, a quantum computer could theoretically take every path at once. In the same way that every city exponentially increases the complexity of the problem, every qubit you add to a computer results in an exponential increase in its ability to solve problems.

Quantum computing in practice

While the importance and the multitude of use cases that will arise from quantum computing is certain, the exact time frame of when quantum computers will be scaled to be used in practical applications is a little muddier. Tech giants across the world are racing to increase the amount of qubits in their quantum computers and reduce the error rates that currently limit the sophistication of quantum computation. In 2019, Google officially announced that it had achieved quantum supremacy (the moment that a quantum computer outperforms a classical computer).

Google revealed that its 54-qubit Sycamore processor was able to perform a calculation with around 9 quadrillion steps in just 200 seconds, which would have taken the world’s most powerful supercomputers 10,000 years to solve.4 IBM later rebutted this by claiming – but not proving – it would, at most, take a classical system 2.5 days to solve, and with greater additional refinements likely much faster.5 Nevertheless, this milestone was highly significant. On top of tech giants, quantum startups such as Rigetti are also starting to develop technology and disrupt the space. Rigetti is leading a £10m consortium to create the UK’s first commercially available quantum computer.6 Efforts from startups, combined with government initiatives like the EU Quantum Flagship, are highly significant for maintaining the relevance of the EU and diversifying technological leadership beyond American tech giants in the quantum race.7

“In 10 years’ time we will be able to achieve things that would be unthinkable today“
Christian Rathke
Innovation and Technology Manager, G+D

As we learned from the battle between Sony’s Betamax and JVC’s VHS in the 1980s, which involved the development of different formats for the same application8 – we don’t yet know which company, solution, or hardware will win the quantum race. We do, however, know that many powerful protagonists will push their ideas, and the real-life applications of quantum computing will continue to develop rapidly in the next few years. Christian Rathke, Innovation and Technology Manager, G+D, strongly believes in the revolutionary power of quantum technology. “Quantum computing is a key technology that will cause a leap for mankind. While universal quantum computers are not ready yet, in 10 years’ time we will be able to achieve things that would be unthinkable today,“ he says.

One industry set to hugely benefit from quantum computing is banking. Quantum computing would allow faster and more accurate decision-making, for example in optimizing investment portfolios, speeding up computationally intense pricing calculations, and sharpening decision-making for tailored services.9 However, it could also present a threat to financial systems, as a quantum computer could bypass existing security, which underpins digital currencies, such as CBDC. Here, quantum-resistant algorithms will become crucial.

The new frontier: post-quantum cryptography

Multiple layers of a transparent and gold padlock with coding written on it, representing post-quantum cryptography
To reap the benefits of quantum computing, we must ensure that quantum-secure algorithms are able to firmly protect our currencies, identities, and communication

As with most technological innovations, with such potential also comes great risk. The ability to overcome such complex problems and encryptions with the speed and efficacy afforded by quantum computing creates the need for post-quantum cryptography. In order to securely encrypt credit cards, digital identities for border control, smart homes, confidential communication, and autonomous vehicles, post-quantum cryptography must enable mathematical problems that even a quantum computer cannot calculate. Asymmetric or public-key cryptography, a cornerstone of public key infrastructure (PKI), could be significantly affected, as this is fundamental in securing our payment systems, mobile networks, and online communication.10 For example, if someone could forge a seemingly valid passport through quantum technology, our border control systems would become ineffective. Quantum-proof cryptography must create an impenetrable barrier against a quantum computer, and every component must be watertight against a possible flood of cyber-attacks. If one component is badly coded – for example, if the entertainment system of an autonomous vehicle can be penetrated – then the entire system is vulnerable to attacks. This highlights the importance of end-to-end cybersecurity.

Another emerging threat is that of “store now, decrypt later.” Theoretically, if one stores encrypted classified government or military information that currently cannot be decrypted, the information could be uncovered and leaked a decade from now, by which time the technology could be available. This shows how time-sensitive the development of quantum-resistant cryptography is. One step that has already been taken in this direction is quantum key distribution (QKD), an alternative way to change keys for secure communication. It uses the physics of quantum mechanics to create a shared secret between two parties. China is investing a lot in research for intelligence to achieve confidential internet communication with this method. However, QKD currently has severe limitations in terms of measurable distance and bandwidth.11  

Steps toward the post-quantum era

Quantum computing is no longer a foundational problem; it has now become an engineering problem. Important thresholds have already been breached, and huge technological developments have been made. However, we still have a long way to go to reach practical applications. An important element in this race is the development of standards to ensure that the proper security protocols are developed. Standardization plays an important role, as it is the basis of security. The National Institute of Standards and Technology (NIST) in the US is setting up encryption standards to withstand quantum computing. The target is to have a portfolio of standards by the end of 2022 that provides the tools to protect sensitive information into the foreseeable future. This will presumably offer a choice of lattice-based, multivariate, and code-based cryptographic algorithms in order to cover a variety of approaches to protection.12

To achieve important use cases like developing battery cells or optimizing traffic routes, integration and collaboration between different players will be key. “From secure identities to CBDC and everything that is connected, it all must be secure, especially against threats we will face in 10 years,” says Rathke. “That is the absolute foundation of post-quantum IoT security – to connect everything with each other and ensure it is completely quantum-safe.” While the risks of quantum computing are high, the incredible applications and opportunities are even higher.

  1. “IBM & Daimler use quantum computer to develop next-gen batteries,” IBM, 2020

  2. “Microsoft Quantum helps Case Western Reserve University advance MRI research,” Microsoft, 2018​​​​​​​

  3. “Inside big tech’s high-stakes race for quantum supremacy,” Wired, 2020​​​​​​​

  4. “Computing takes a quantum leap forward,” Google, 2019

  5. “IBM says Google may not have reached quantum sypremacy,” New Scientist, 2019

  6. “Rigetti to build UK’s first commercial quantum computer,” Financial Times, 2020

  7. “Quantum Flagship,” EU, 2021

  8. “Betamax versus VHS,” Quantum Computing Report, 2021

  9. “How quantum computing could change financial services,” McKinsey, 2020

  10. “Asymmetric cryptography,” Science Direct, 2020

  11. “Universal limitations on quantum key distribution over a network,” Cornell University, 2020

  12. “NIST’s Post-Quantum Cryptography Program,” NIST, 2020

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