Finite-key Analysis for Quantum Conference Key Agreement with Asymmetric Channels
This work addresses a practical bottleneck in quantum networks for secure multi-party communication, representing an incremental advancement over existing protocols.
The paper tackles the problem of low key rates and short transmission distances in quantum conference key agreement over asymmetric channels by proposing a tripartite protocol that removes symmetry conditions and includes a finite-key security analysis. The result is a significant improvement in feasibility for establishing conference keys, with concrete gains in efficiency and security.
As an essential ingredient of quantum networks, quantum conference key agreement (QCKA) provides unconditional secret keys among multiple parties, which enables only legitimate users to decrypt the encrypted message. Recently, some QCKA protocols employing twin-field was proposed to promote transmission distance. These protocols, however, suffer from relatively low conference key rate and short transmission distance over asymmetric channels, which demands a prompt solution in practice. Here, we consider a tripartite QCKA protocol utilizing the idea of sending-or-not-sending twin-field scheme and propose a high-efficiency QCKA over asymmetric channels by removing the symmetry parameters condition. Besides, we provide a composable finite-key analysis with rigorous security proof against general attacks by exploiting the entropic uncertainty relation for multiparty system. Our protocol greatly improves the feasibility to establish conference keys over asymmetric channels.