  In this paper, a semiquantum secret sharing (SQSS) protocol based on x-type
states is proposed, which can accomplish the goal that only when two classical
communicants cooperate together can they extract the shared secret key of a
quantum communicant. Detailed security analysis turns out that this protocol is
completely robust against an eavesdropper. This protocol has some merits: (1)
it only requires one kind of quantum entangled state as the initial quantum
resource; (2) it doesn't employ quantum entanglement swapping or unitary
operations; and (3) it needn't share private keys among different participants
beforehand.
