Quantum cryptography should not be confused with post-quantum cryptography (PQC). Unlike PQC and conventional cryptography, which rely on mathematical approaches, the security of quantum cryptography is based on the laws of quantum physics.
One of the main quantum cryptography protocols currently in use is Quantum Key Distribution (QKD). This method enables two users to exchange encryption keys, allowing them to securely encrypt and decrypt the data they share while preserving confidentiality and integrity.
This was precisely the focus of the three-year Carnot SEQUANCES project, led by CEA-Leti since early 2023. Its primary objective was to characterize potential physical attacks targeting the optical-to-digital interface of QKD systems, with the goal of advancing knowledge of the technology and contributing to its maturity.
What exactly is the optical-to-digital interface?
The question was whether this interface could represent a vulnerability exploitable by attackers.
The project therefore investigated whether photon detection and processing could be subject to so-called side-channel observation attacks.
These questions had received very limited attention in the scientific literature until now.
The SEQUANCES project delivered important results for understanding the optical-to-digital interface of QKD systems. It has significantly strengthened CEA-Leti's expertise in quantum cryptography, complementing another initiative, QCommTestbed, funded by the French National Research Agency (ANR) through the Quantum PEPR program.
QCommTestbed brings together nine partners, including CEA-Leti, with the objective of establishing a coordinated national testing platform for quantum technologies in France.
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