Conference Key Agreement and Quantum Sharing of Classical Secrets with Noisy GHZ StatesConference Key Agreement • October 30th, 2018
Abstract— We propose a wide class of distillation schemes for multi-partite entangled states that are CSS-states. Our proposal provides not only superior efficiency, but also new insights on the connection between CSS-states and bipartite graph states. We then consider the applications of our distillation schemes for two cryptographic tasks—namely, (a) conference key agreement and (b) quantum sharing of classical secrets. In particular, we construct “prepare-and-measure” protocols. Also we study the yield of those protocols and the threshold value of the fidelity above which the protocols can function securely. Surprisingly, our protocols will function securely even when the initial state does not violate the standard Bell-inequalities for GHZ states. Experimental realization involving only bi-partite entanglement is also suggested.
Efficient source-independent quantum conference key agreementConference Key Agreement • June 26th, 2024
Quantum conference key agreement (QCKA) enables the unconditional secure distribution of conference keys among multiple participants. Due to challenges in high-fidelity preparation and long-distance distribution of multi-photon entanglement, entanglement-based QCKA is facing severe limitations in both key rate and scalability. Here, we propose a source-independent QCKA scheme utilizing the post-matching method, feasible within the entangled photon pair distribution network. We introduce an equivalent distributing virtual multi-photon entanglement protocol for providing the unconditional security proof even in the case of coherent attacks. For the symmetry star-network, comparing with previous n-photon entanglement protocol, the conference key rate is improved from O(ηn) to O(η2), where η is the transmittance from the entanglement source to one participant. Simulation results show that the performance of our protocol has multiple orders of magnitude advantages in the intercity distance.
Conference Key Agreement and Quantum Sharing of Classical Secrets with Noisy GHZ StatesConference Key Agreement • December 15th, 2008
Fully device independent Conference Key AgreementConference Key Agreement • November 21st, 2020
Quantum communication allows cryptographic security that is provably impossible to obtain using any classical means. Probably the most famous example of a quantum advantage is quantum key distribution (QKD) [1, 2], which allows two parties Alice and Bob to exchange an encryption key whose security is guaranteed even if the adversary has an arbitrarily powerful quantum computer. What’s more, properties of entanglement lead to the remarkable feature that security is sometimes possible even if the quantum devices used to execute the protocol are largely untrusted. Specifically, the notion of device independent (DI) security [3, 4] models quantum devices as black boxes in which we may only choose measurement settings and observe measurement outcomes. Yet, the quantum state and measurements employed by such boxes are unknown, and may even be prepared arbitrarily by the adversary.
Repeater-Like Asynchronous Measurement-Device-Independent Quantum Conference Key AgreementConference Key Agreement • June 25th, 2024
between the users and the port of interference is the same as virtual protocol 1. (iii) The users identify which specific GHZ state was measured according to the click events at each detection port. Steps (iv) and (v) are the same as those in the virtual protocol 1.
