Afonso DELERUE ARRIAGA Research Faces DeLUX

I came to Luxembourg in 2013 to do a PhD in cryptography at the University of Luxembourg. I was a researcher in Portugal when I came in contact with researchers from the SnT with common interests. With their support, I applied for an AFR individual grant, one of FNR funding schemes. I was incredibly fortunate to see my project proposal accepted, and Luxembourg became my home.

After completing my doctoral studies, I was looking forward to putting the knowledge I’ve acquired to practical use. I took a job in a public agency, where I managed the Public Key Infrastructure for Luxembourgish passports and worked on international standards for globally interoperable electronic travel documents and on the specifications of the EU Digital Covid Certificate.

Research has always been at the center of what I enjoyed doing the most. I also like teaching, which unfortunately was no longer part of my life. So, this year I moved back to the University. What better place to work for that combines research and teaching?

It's also a great opportunity to study recent developments in my field and leverage my experience from the industry in order to (hopefully) make a meaningful contribution to science.

I currently live in Luxembourg City, with my wife and our 2-year-old son. We are both working parents, but my work is very goal-oriented, which comes with some scheduling flexibility and therefore offers a great work-life balance.

My research consists in designing cryptographic key exchange protocols that are future-proof in the event attackers build or gain access to a quantum computer. Most of commonly employed public-key protocols can be broken by large scale quantum computers, and transition to post-quantum algorithms is still in its infancy.

I speak Portuguese, English end French. In Luxembourg, everyone speaks surprisingly many languages, and communication has never been a difficulty.

What do you like most about your job?

I like the freedom to work on the problems I care about. I like the creativity, independent thinking and brain-teasing aspects of research. I like that people in the research community are always willing to share their knowledge and discuss new ideas.

How would you describe your job to a undergraduate student?

Privacy is really important, especially in a digital world. A common approach for two parties to communicate privately is to first agree on a secret key, and then use this key to encrypt and authenticate messages. If the two parties share a common password, there are known protocols they could follow to safely agree on a secret key, even if attackers are listening or interfering with the messages being exchanged. These protocols are called Password-Authenticated Key Exchange (or PAKE, for short) and are used in many places. For instance, when we connect our laptop to a WiFi network, our laptop and WiFi router might engage in such protocol, so that people nearby cannot eavesdrop on our communications. Or when we travel and handle our passport to the border control agent, our passport and the reader machine also engage in a PAKE protocol first, before the data in our passport could be read and displayed to the agent. Smart devices at home might also execute these protocols prior to engaging in further communication. There are many examples.

Even though these protocols are meant to resist attackers with very powerful computers, they might no longer be secure against attackers with a new kind of computers called quantum computers. This type of computers takes advantage of the properties of quantum states and are capable of solving certain computational problems that classical computers cannot. Today, quantum computers are still too small to pose a threat to PAKE protocols, but it is time to design new protocols that are post-quantum resistant. My job is to design these protocols, so that private communication can still take place in the future.

What makes doing research in Luxembourg special?

Luxembourg is a very multicultural country, and the diversity of backgrounds adds the research landscape. The University of Luxembourg encourages collaboration with other universities, research centers and the industry, especially in key areas. This is also supported by multiple FNR funding schemes.

What would you miss most when leaving Luxembourg?

Some good friends I've made here. And also Crémant de Luxembourg!

What’s your advice for a newcomer to Luxembourg?

Even though it’s a relatively small country, commuting by car during rush hour can be an unpleasant experience. I would advise taking the commute into account when choosing where to live. On the positive side, public transportation is completely free! For short commutes within Luxembourg City, vel'OH! city bikes are a great option as well. All bikes are now electric power assisted and the annual subscription fee is symbolic.