Abstract
As an essential application of quantum mechanics in classical cryptography, quantum secret sharing has become an indispensable component of quantum internet. Recently, a differential phase shift quantum secret sharing protocol using a twin field has been proposed to break the linear rate-distance boundary. However, this original protocol has a poor performance over channels with asymmetric transmittances. To make it more practical, we present a differential phase shift quantum secret sharing protocol with asymmetric source intensities and give the security proof of our protocol against individual attacks. Taking finite-key effects into account, our asymmetric protocol can theoretically obtain the key rate two orders of magnitude higher than that of the original protocol when the difference in length between Alice’s channel and Bob’s is fixed at 14 km. Moreover, our protocol can provide a high key rate even when the difference is quite large and has great robustness against finite-key effects. Therefore, our work is meaningful for the real-life applications of quantum secret sharing.
Highlights
Secret sharing is a cryptographic protocol in which a dealer splits a secret into several parts and distributes them among various players
Differential phase shift quantum secret sharing (QSS) scheme using coherent light [20], similar to those used in quantum key distribution (QKD) [21,22,23,24,25,26], has been proposed and implemented
Because of the equivalence [29] between our asymmetric protocol and differential phase shift QSS, we can apply the conclusion in differential phase shift quantum key distribution [25] to the analysis of both an external eavesdropper and an internal eavesdropper in our protocol
Summary
Secret sharing is a cryptographic protocol in which a dealer splits a secret into several parts and distributes them among various players. To exceed the linear bound and further enhance the practical performance of QSS, a differential phase shift quantum secret sharing (DPSQSS) protocol [29] using a twin field (TF) [30] has been proposed. This protocol suffers from low key rate and short transmission distance over channels with different transmittances, which constrains its application in a practical network setting. Parameter estimation: Charlie randomly chooses recorded detection times and Alice and Bob alternatively disclose her or their test bit first in the chosen time slots through a public channel. Postprocessing: After calculating the QBER, Alice, Bob, and Charlie will conduct classical error correction and privacy amplification to distill the final full key and partial keys
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