Abstract
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.
Highlights
Remote distribution of secret key is an essential task of quantum cryptographic network
To extend Quantum key distribution (QKD) to multiparty scenarios, one intuitive way is to refer to classical conference key agreement [21, 22]
Basic laws of quantum mechanics combined with one-time pad encryption [30] guarantee the security of multiparty quantum communication [24, 31]
Summary
Remote distribution of secret key is an essential task of quantum cryptographic network. To achieve higher conference key rate and longer transmission distance, some protocols inspired by the idea of twin-field QKD were proposed [44,45,46]. All of these protocols neglect the case of asymmetric channels, which makes them impractical. With the similar devices as twin-field QKD [52, 53], our protocol has a longer transmission distance, a higher key rate and is more practical than other QCKA protocols [40]. With the extension of twin-field QKD to QCKA, we perform a finite-key analysis [35, 54,55,56] with multiparty composable security to make our work more practical
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