22 September 2025
Today, it’s almost impossible to obtain certain services or log on to our bank accounts without revealing personal information, leaving us vulnerable. Claude Crépeau, full professor in the Department of Software Engineering and Information Technology at ÉTS and cryptography expert, is convinced that we will soon be able to confirm our identity to a third party without revealing confidential data. Proof of knowledge with zero disclosure represents a major step forward.
Quantum Technology Comes to ÉTS
Claude Crépeau was a member of the Quantum Computing Program at the Canadian Institute for Advanced Research, from 2003 to 2013. He held the position of Associate Professor at Université de Montréal for a few years, then at the McGill University School of Computer Science for twenty-six years. On January 1, 2025, he joined ÉTS to contribute to the development of the Quantum Science and Engineering Institute . “I’m one of the first two researchers to form the core of this new institute integrated into ÉTS,” announces the cryptologist. Professor Crépeau intends to take his research further and ensure closer cooperation between ÉTS and the Quebec ecosystem of quantum companies.
When the Curve of a Ball Paves the Way…
As a child, Claude Crépeau was fascinated by physics. Why does a baseball curve when you hit it? What principles govern the universe? “I wanted to become a scientist like Professor Calculus in Tintin,” he confesses. However, in CEGEP, Claude found the computer science teachers more interesting than the physics teachers. So he enrolled in Computer Science at Université de Montréal.
At the time, an article published in 1983 in Scientific American magazine on public key cryptography caught his attention. This new method encrypted data with a public key, which only recipients could decrypt with their own private key. This ensured the confidentiality of the exchanges. On learning that Professor Gilles Brassard of Université de Montréal and his colleague Charles Bennett were applying the properties of quantum physics to cryptography, Claude Crépeau offered his collaboration. He never looked back!
In 1984, he earned his bachelor’s degree in mathematics and computer science from Université de Montréal and, two years later, a master’s degree in computer science. In 1989, he earned his PhD in computer science with a focus on cryptography from the Massachusetts Institute of Technology (MIT).
ÉTS Professor Claude Crépeau
In 1993, the young cryptographer contributed to the discovery of quantum teleportation, a revolutionary technology that transmits quantum information using classical information and entanglement. Both resources depend on each other to succeed at this task.
Quantum Technology, a Challenge for Scammers
Conventional computer systems operate on a simple principle: information is encoded using 0s and 1s, known as bits. This binary system can translate any data, be it letters, numbers, images or sound. However, scammers can intercept the transmitted data, then falsify or duplicate it.
Quantum computing systems use qubits that can be both 0 and 1 simultaneously. This enables them to process more information exponentially than traditional computers. It’s also what makes cryptography more secure. Transmissions cannot be intercepted without altering the quantum state of the qubits. This alteration is immediately detectable.
Claude Crépeau is examining applications in cryptography, especially more secure identification methods. According to the theory of relativity, information cannot travel faster than the speed of light—this is an absolute limit. “To cheat, scammers will need to communicate faster than light, and we don’t think that’s possible in our universe,” sums up Claude Crépeau.
Who could have imagined the impact of a baseball’s trajectory on the sharp mind of a little boy emulating Professor Calculus!
