A multi-proxy quantum group signature scheme with threshold shared verification is proposed.An original signer may authorize a proxy group as his proxy agent.Then only the cooperation of all the signers in the proxy group can generate the proxy signature on behalf of the original signer.In the scheme,any t or more of n receivers can verify the message and any t 1 or fewer receivers cannot verify the validity of the proxy signature.
This paper proposes a circular threshold quantum secret sharing(TQSS) scheme with polarized single photons.A polarized single photon sequence runs circularly among any t or more of n parties and any t or more of n parties can reconstruct the secret key when they collaborate.It shows that entanglement is not necessary for quantum secret sharing.Moreover,the theoretic efficiency is improved to approach 100% as the single photons carrying the secret key are deterministically forwarded among any t or more of n parties,and each photon can carry one bit of information without quantum storage.This protocol is feasible with current technology.
