Countless millions of messages are sent every day via messaging services such as WhatsApp or Signal. These are more or less private messages that recipients receive via end-to-end encryption. To ensure that they are exchanged securely, a personal key is stored in the application when the user logs in that can be used to convert the plain text into so-called ciphertext and vice versa. Yet how can this key be securely exchanged without the provider of the service knowing the code? “After all, we don’t want the large corporations behind these services to be able to read our messages”, says Dr. Christian Janson, a postdoc in the Cryptography and Complexity Theory Group in the Department of Computer Science at TU Darmstadt.
Continuously checking the security models
The exchange of our data and messages is now largely secure thanks to end-to-end encryption. “However, we still need to continuously check the models to uncover possible weaknesses for attacks and take corresponding measures. It is important to make the key exchange process secure, especially in light of the quantum computer technology of the future”, explains the 34-year-old scientist.
Janson developed an interest in cryptography while studying for his degree in mathematics. The researcher, who was born in Kaiserslautern, originally wanted to become a teacher but decided to study for a diploma in theoretical mathematics instead at the University of Bremen. He then took a course in cryptography in the 6th semester. “It fascinated me so much that I stayed with it”, he recalls. His doctorate focussed on cryptographic methods to verify the correctness of calculations outsourced to cloud providers.
Darmstadt is one of the most important locations for IT security and cryptography in Germany
Learning from the best
He moved to the Royal Holloway College at the University of London in 2012 to complete his doctoral thesis. “The Royal Holloway, University of London, is home to one of the most well-known research groups for information security”, says the mathematician. The college is located a little outside the metropolis in Victorian brick buildings “that look like the Hogwarts school in Harry Potter”, adds Janson with a smile. He looks back fondly on his four years as a doctoral candidate in England. And when he looks out of his current office window, the historical façade of the old main building at TU Darmstadt reminds him a little of those days.
Janson assumed his current position as a postdoc in the Cryptography and Complexity Theory Group in July 2016. This was one month after the Brexit vote in the United Kingdom but it was mainly family reasons that led him to leave the island and return to Germany. The good reputation of TU Darmstadt motivated the young researcher to submit an application. “Darmstadt is one of the most important locations for IT security and cryptography in Germany”, he says. The expectations he had of his new position have in his words been “more than fulfilled”. In the research group headed by Professor Marc Fischlin, Janson believes that he is “learning from one of the best”. He appreciates the interdisciplinary aspect of his work and the exchange of ideas in the team with mathematicians and computer scientists “who constantly give really important practical input”.
Funding as an “Athene Young Investigator” now gives him the opportunity “to work and carry out his research more independently”, he explains. The 34-year-old scientist is looking forward to being able to spend more time teaching students in the future and supervising doctoral candidates. “It is step on the career ladder towards a professorship.”