What we do:
Future information and communication networks will certainly consist of both classical and quantum devices, some of which are expected to be dishonest, with various degrees of functionality, ranging from simple routers to servers executing quantum algorithms. In a hybrid quantum and classical approach, we consider three plausible scenarios, from the closest to the furthest foreseeable future, and try to study them thoroughly by elaborating adversarial models and designing or analysing concrete protocols with formal security proofs, in order to get ready as soon as one of these scenarios becomes the new reality. The first scenario considers post-quantum cryptography as in the NIST’s standardization, i.e. classical cryptography resistant to a potential quantum adversary, without giving any quantum resource to the honest people. In the second scenario, we assume that quantum communication is accessible to anybody and we try to take advantage of it in what we call quantum-enhanced classical cryptography. Finally, in the third scenario, we go one step further, assume a completely quantum world and investigate the consequences on the security of cryptography. In each case, we need to assess the powers of the attacker and to find the most relevant security models.