A clear plan for security
ETH professor Ueli Maurer has provided cryptography with a theoretical basis. Now he is retiring. However, his most important research project is yet to come.
We meet for an interview on his 65th birthday – a coincidence. Ueli Maurer points to a grey container in front of his office and says with a grin: “Everything’s ready.” He is talking about his retirement at the end of July.
But it is not over – what comes next will be the most important part of his career: “I want to complete a theory that I’ve been working on for a long time. I’m not under any duress or pressure, but I have a clear plan.”
Maurer is a cryptologist. Cryptology looks at how information can be transmitted securely. It underpins applications such as e-banking, e-commerce and digital currencies.
The mission: proving security mathematically
Maurer is one of the best in the world in his field. Not least because he understands the theory underpinning his subject like few others do. To have a clear plan and a fundamental understanding of things was what he set out to achieve from the very beginning.
Maurer’s enthusiasm for the subject all stems from a lecture he attended, delivered by former ETH professor and cryptologist Jim Massey. It was striking in how it stood out to him: crystal clear, well structured and with a clear goal. Massey said of himself that he could only understand simple things. For that reason, it was necessary to abstract complex issues and reduce them to their key elements. This resonated with Maurer.
In 1990, he completed his PhD with Massey and immediately entered a new field. He demonstrated that the security of cryptographic processes could be mathematically defined and proven. For example, an attacker being unable to crack a key even if he eavesdropped on everything.
This is important because unlike functionality (a lamp lighting up), security (an aeroplane not crashing, a key being uncrackable) cannot be measured or tested. The definition of security is that something does not happen. And because there are an infinite number of potential attacks, security cannot be conclusively tested. That is why you have to prove it mathematically.
After spending time at Princeton University, Maurer returned to ETH Zurich in 1992 as an assistant professor. Shortly thereafter, he published a paper demonstrating for the first time how difficult it is to crack the Diffie-Hellmann key exchange, a process through which two people can exchange a secret key via an insecure channel.
Maurer’s work changed cryptology
Maurer’s work caused quite a stir. From then on, it became standard practice to mathematise cryptographic processes and to be able to prove their security by making certain assumptions. His research laid the foundations for new, more secure systems. He developed some of them himself and had them patented.
For instance, an encryption method that can withstand even infinite computing power and theoretically survive in the age of quantum computers. Earlier encryption systems were based on the premise that attackers would need to carry out calculations for thousands of years or longer to crack them. As part of the new method, Maurer used physical properties for encryption, such as signal noise in transmission channels.
Maurer has also spent many years looking at how security can be ensured in distributed systems and networks. He worked on the theoretical foundation for applications such as blockchain at an early stage. In 2018, he co-founded Concordium, a blockchain-based platform for secure transactions.
Markus Püschel, ETH Professor of Programming Languages and Systems and friend of Maurer, says: “Ueli is a researcher through and through who thinks about things in a very fundamental way and with a long-term perspective. He has influenced many younger researchers with his way of doing things.” For these qualities, among others, Maurer has won numerous awards, including the Test of Time Award, which recognises work that has been influential over the long term, and the RSA Award for Excellence in Mathematics.
“If I want to teach something, I have to really understand it first.”Ueli Maurer
Teaching brings insights
Teaching is another pursuit that is particularly close to Maurer’s heart. For him, teaching is inextricably linked to research and serves as a source of new insights. He says: “If I want to teach something, I have to really understand it first.”
He was therefore particularly delighted when students dedicated an advert to him in a external page commuter newspaper in 2019 in recognition of his teaching. The students thanked him for the way he taught the complex subject matter.
It was one of his finest moments as an ETH professor, he says. The students took out the advert as part of the newspaper’s anniversary campaign and dedicated it to the computer science professor. It featured a page from Maurer’s lecture notes on discrete mathematics – not a very popular subject.
Contacted by the intelligence service
In 2020, in the middle of the pandemic, Maurer found himself in the public eye for a different reason. The media was reporting that Omnisec, a manufacturer of encryption devices, had been infiltrated by intelligence services – just like the company Crypto AG. Maurer had worked as a consultant for Omnisec for a long time.
Shocked, Maurer spoke about the matter on the Swiss television programme Rundschau and in various newspapers, stating that he had actually been contacted by the American intelligence service NSA in 1989. He categorically rejected these attempts to exert an influence and immediately distanced himself from them. He also notified the head of the company at that time. Following this, he was convinced that the matter had been settled and that the company was clean.
A comprehensive theory
Alongside his research and teaching, Maurer also served as a Director of Studies and sat on various committees. All of these were important duties that he enjoyed performing.
Nevertheless, he is looking forward to being able to fully devote himself to his research once again following his retirement. The time has come for his brilliant feat: developing a constructive theory of cryptography – that is, a scientific basis for the systematic and comprehensible design of cryptographic processes. Like in a modular system, it should be possible to securely combine individual building blocks with one another in order to construct complex encryption protocols – and to mathematically guarantee their security.
“we currently rely far too much on a technology whose security we still don’t understand to a sufficiently systematic degree.”Ueli Maurer
“Such a theory is long overdue,” he says, “because we currently rely far too much on a technology whose security we still don’t understand to a sufficiently systematic degree.”
He regrets and criticises the fact that understanding in and of itself is becoming less important in research. “Research should be about acquiring knowledge, about intellect. But large parts of the world of academia don’t work this way. PhD students are already being trained to publish as many scientific papers as possible. Unfortunately, in doing so, they often produce things that are publishable but not really relevant.”
As a result, many fundamental problems in science remain ignored and unsolved, he says. Finding and resolving these blind spots is often a thankless task. He knows from experience that it takes a thick skin and a high tolerance for frustration to work on something new, but these make the subsequent reward and satisfaction all the greater.
He is not going to give up: “The cryptography theory I am searching for already exists. It is just a case of discovering it.”
The plan for what comes next
But what if it doesn’t work out? “That would be okay too. Then someone else will discover it. It is about the subject, not about me.” He sounds very relaxed as he says this. Because he is, of course, already preparing for the day when he will have to leave research behind because he can no longer meet the required level of intellectual performance: Maurer, the security researcher who often used to fly hang gliders, is currently learning to fly glider aircraft. “This is a field I can keep on developing in for a good while to come,” he says.
He is not flying big distances yet, just from Amlikon to the Toggenburg region. Every kilometre gained with thermals makes him happy, he says. But no one would be surprised if he was already planning to fly over the Alps.