The need for secrecy and security is essential in communication. Secretsharing is a conventional protocol to distribute a secret message to a group ofparties, who cannot access it individually but need to cooperate in order todecode it. While several variants of this protocol have been investigated,including realizations using quantum systems, the security of quantum secretsharing schemes still remains unproven almost two decades after their originalconception. Here we establish an unconditional security proof for continuousvariable entanglement-based quantum secret sharing schemes, in the limit ofasymptotic keys and for an arbitrary number of players. We tackle the problemby resorting to the recently developed one-sided device-independent approach toquantum key distribution. We demonstrate theoretically the feasibility of ourscheme, which can be implemented by Gaussian states and homodyne measurements,with no need for ideal single-photon sources or quantum memories. Our resultscontribute to validating quantum secret sharing as a viable primitive forquantum technologies.
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