  We propose a multiparty quantum cryptographic protocol. Unitary operators
applied by Bob and Charlie, on their respective qubits of a tripartite
entangled state encodes a classical symbol that can be decoded at Alice's end
with the help of a decoding matrix. Eve's presence can be detected by the
disturbance of the decoding matrix. Our protocol is secure against
intercept-resend attacks. Furthermore, it is efficient and deterministic in the
sense that two classical bits can be transferred per entangled pair of qubits.
It is worth mentioning that in this protocol same symbol can be used for key
distribution and Eve's detection that enhances the efficiency of the protocol.
