This cryptograph helps to quantum proof the internet

Therefore, in 2016, NIST launched a competition looking for new encryption approaches resistant to quantum computers. In 2022, the agency announced the first round of winners, which included the CRYSTALS-Kyber scheme, co-authored by Bos, who is the technical lead of the post-quantum cryptography team at NXP Semiconductors in Leuven, Belgium.

Today, Bos is focused on integrating the algorithm into NXP’s portfolio of embedded hardware products, which includes chips for credit cards, contactless payment terminals, IoT devices and automobiles.

As someone who loves solving puzzles, Bos was well suited for a career in cryptography, he says. The fact that he can help make the world a safer place while doing something he enjoys is a huge bonus.

“If this research was practically useless, I’d probably still be doing it,” he says. “But it’s great that you can work on interesting math puzzles, and in the end it will have a very positive impact on everyone around you.”

Discovering Cryptography

Growing up in a small town near Haarlem in the Netherlands, Bos was fortunate enough to be introduced to technology early on. His father worked in a bank and had a desktop computer at home. Bos started using it to play video games, but became fascinated by the underlying technology and quickly learned to code. At the age of 15, he was already doing freelance programming work for various companies.

In high school, he learned about more formal computer science topics such as algorithms and computational complexity. These subjects fascinated him, and in 2001 he enrolled at the University of Amsterdam to earn a bachelor’s degree in computer science. After graduating in 2004, he stayed on to earn a master’s degree in grid computing, which he completed in 2006.

“If you design a great algorithm, it might end up in Microsoft’s crypto library.”

While working on his master’s degree, Bos says he was moving toward algorithm design and more mathematically demanding computer science, but he also wanted to continue working on practical problems. Then he discovered cryptography, which spanned his interests. “It’s really the intersection of engineering, computer science and mathematics,” he says.

This realization prompted Bos to apply for a PhD program in the laboratory of renowned cryptographer Arjen Lenstr at the École Polytechnique Fédérale de Lausanne in Switzerland. Bos was adopted and launched in 2007, just as the lab was beginning to explore using unconventional hardware—such as game consoles—to perform cryptanalysis, the process of breaking encryption.

His Ph.D project involved creating a cluster of over 200 PlayStation 3 consoles and using it to crack a popular encryption scheme based on the mathematics of elliptic curves. The console’s multi-core processors used the Cell architecture developed by IBM, Sony, and Toshiba, which was well-suited to running multiple computing processes in parallel, as required in cryptanalysis.

Learning about lattices

During his doctoral studies, Bos worked on a summer project with another respected researcher, Peter Montgomery, who was working at Microsoft Research at the time. The pair clicked, Bos says, and he was invited to become a postdoctoral researcher in Montgomery’s lab in Redmond, Wash., after he completed his Ph.D. in 2012.

The transition from academia to corporate R&D was an invaluable experience, Bos says, seeing how research translates into real products. “It was really motivating,” he says. “If you design a great algorithm, it could end up in Microsoft’s crypto library, which is then used by hundreds of millions of people around the world.”

While at Microsoft, Bos began working on an emerging approach known as lattice-based cryptography, which relies on vector mathematics in a lattice. These schemes were promising because they could be used for both quantum-secure encryption and fully homomorphic encryption, a technique that allows computations to be performed on encrypted data without first decoding it.

But after two years in the United States, Bos and his wife wanted to be closer to home. So in 2014, he accepted a job as a cryptography researcher at NXP and moved to Belgium. He joined the company’s innovation team, which has been coming up with features for products for several years according to the company’s product roadmap.

Advances in quantum computing made it clear then that more secure approaches to encryption would be important, Bos says. So, working with researchers from Arm, IBM, SRI International, and various universities, he helped design the lattice-based CRYSTALS-Kyber encryption scheme that was submitted to NIST in 2017.

From cryptography research to products

Since then, Bos has focused on implementing the algorithm into NXP’s embedded hardware. Grid-based encryption requires significantly more memory than older approaches, making it difficult to run on smaller chips, such as those found in ID cards or IoT sensors. His team had to make changes to the underlying math of the algorithm and redesign it to run on these specialized chips.

Bos says his work has evolved significantly over the years. He went from doing pure research to leading a team and working closely with other departments to translate their innovations into real products. He had to work hard to develop the skills to act as an interface between engineering and business-focused teams, he says.

Being the team leader is a very challenging role, he says, as NXP needs to stay on the cutting edge of post-quantum encryption. The chips he designs are used at the beginning of a long supply chain, he explains, because they must be integrated into larger systems made by component manufacturers. These systems are then sold to equipment manufacturers or car companies, who must integrate them into final products.

Each of these steps can take years, says Bos. This means that NXP chips must be quantum secure now so that end-users can meet government-recommended deadlines for transitioning to post-quantum encryption by the early 2030s.

Friendly field

One of the things Bose likes most about crypto is that the field is relatively small and welcoming. “Everyone is super friendly,” she says. “If you go to a crypto conference, the big names, the people who really invented crypto in the 1970s, still come to these events and you can meet them in person.”

The size of the field also means that cryptography experts are in short supply, Bos adds, making it a discipline with great career prospects. While many roles require strong math skills, there are plenty of opportunities for those with more conventional computer science backgrounds, and companies are always looking for electrical engineers to build cryptographic hardware.

A graduate degree in one of these fields is a bonus, but companies like NXP do a lot of in-house training, so it’s not strictly necessary, Bos says. Taking cryptography or security courses online or at a university can make a big difference, he adds. But the most important thing is the right approach. “You just have to be motivated, curious and willing to learn,” says Bos. “I think those are really the biggest factors.