Quantum cryptography has been largely defined as a novel form of cryptography that would not rely on computational hardness assumptions but on information-theoretic security. Recent notions such as quantum pseudorandomness and uncloneable quantum cryptography have however shown the fundamental interest of cryptographic schemes leveraging computational assumptions . At Quriosity, we have specifically introduced a new hybrid security model, named quantum computational timelock (QCT), that unlocks the possibility to define novel protocols implementable with existing technology, with security gains over classical cryptography, and performance gains over quantum cryptography. We are in particular interested in proving security in this model but also to establish connections with quantum pseudo-randomness but also with realistic optical implemenations.
Associated PIs: Romain Alléaume, Peter Brown
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Device-independent cryptography asserts that certain cryptographic tasks can be securely executed even when implemented on untrusted quantum hardware. This extreme level of security is a consequence of Bell-nonlocality, which acts as an effective black-box test for the inner-workings of the untrusted devices. At Quriosity we are developing new mathematical techniques to analyse the security of these protocols. In particular, using methods from polynomial optimization we are creating new tools to compute the rates of these protocols.
Associated PIs: Peter Brown
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Quantum cryptography requires rigorous mathematical proofs that a given a set of assumptions, a given protocol satisfies a formal definition of secure. Modern security proofs tend to break this procedure into three parts: (i) randomness extraction – relating the security definition to an entropic quantity; (ii) entropy accumulation – breaking the entropy down into tractable chunks; (iii) entropy optimization – minimizing the reduced entropy over all possible attacks from the adversary. At Qurisoity we are developing more efficient security proofs (reduced finite-size effects), tackling each of the three components and unlocking the optimal perfomance of secure quantum cryptography.
Associated PIs: Peter Brown
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Quantum Cryptography(QC) needs to overcome several challenges in order to become widely used in real-world applications. We identify in particular two main challenges: 1) Cryptographic Advantage, namely the capacity of using QC to obtain a competitive edge over existing cryptographic techniques; 2) Security evaluation and certification of quantum cryptographic implementations. Both challenges are at the heart of the EuroQCI initiative that aims to deploy a quantum communication infrastructure in Europe over the coming decade. At Quriosity, we actively contribute to this large program through the different projects at national and European levels: QSNP, ParisRegion QCI, FranceQCI, the CSA action PETRUS, with a focus on CV-QKD implementation security, and the development of use-case for quantum cryptography that are both relevant in terms of security gain, and practicality.
Associated PIs: Romain Alléaume
Relevant works: