Direction de recherche : Eleni DIAMANTI

Co-encadrement : Alex Bredariol Grilo

Protocoles quantiques pour le calcul multipartite sécurisé

When it comes to security, classical and quantum worlds each offer distinct features. Classical solutions offer solid mathematical foundations and easiness of implementation, while quantum ones can enhance the security of cryptographic techniques by making them unbreakable against future technological advancements. A hybrid quantum-safe infrastructure should then offer the best of both worlds. In recent years, basic cryptographic building blocks, called primitives, have been developed in the quantum framework, with the goal of demonstrating a quantum advantage. Quantum communication can famously allow for secure key exchange with information-theoretic security using Quantum Key Distribution (QKD). For other fundamental tasks, security guarantees are more stringent and hybrid solutions, involving so-called post-quantum techniques, which are classical techniques with provable resistance to quantum computing attacks, combined with quantum ones, have proven to offer attractive solutions when considering practicality, efficiency and security at the same time. This is the case, for instance, for the oblivious transfer protocol, which has been studied by our group [Oblivious transfer is in MiniQcrypt, arXiv:2011.14980]. This primitive enables secure multiparty computing, which allows distributed parties to jointly compute a function of their inputs while keeping their inputs private. Because of its practical relevance for applications, this protocol has attracted significant attention in recent years. While the proposed quantum protocols for Oblivious transfer theoretically demonstrate the power of quantum resources in achieving more secure implementations of cryptographic primitives, such protocols are still far from practical. The goal of these thesis is to improve such protocols considering their implementation aspects, so that they could be feasible in the near future. In particular, we aim for protocols whose security is still guaranteed even in the presence of noise and proved for concrete (and realistic) parameters instead of asymptotically. We expect that this thesis will considerably push forward the field of quantum cryptography by providing practical techniques enabling quantum-enhanced secure multiparty computing, opening the way to its use in emergent quantum information networks.